Technical Reports 69-130 (1973 – 1980): 

From 1967 until around 1993 WRRC published many reports on completed projects in-house. These “Technical Reports” contain a wealth of information on water issues, problems, and research, and are all available in PDF format at the University of Hawaii’s ScholarSpace institutional repository. Click on the report titles to go to the PDF.

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Technical Report No. 129
UNDERGROUND RESIDENCE TIMES AND CHEMICAL QUALITY OF BASAL GROUNDWATER IN PEARL HARBOR AND HONOLULU AQUIFERS, OAHU, HAWAII

Theodorus H. Hufen, Paul Eyre, and William McConachie
February 1980

ABSTRACT
Information on the large-scale movement and origin of groundwater in southern Oahu was obtained by examining the natural isotopic and chemical composition of water samples. Six basal groundwater systems (Pearl Harbor, Moanalua, Kalihi, Beretania, Moiliili, and Waialae) were studied and are discussed in this report. The experimental data base comprises the analyses of 84 groundwater samples, 2 surface water samples, and 49 rain-water samples for the following parameters, radiocarbon (14C), carbon (13C), carbon 13 tritium (3H) major ions, nitrate, silica, and pH. These data were supplemented with isotope and chemical data obtained in previous studies and selected data from the literature. Carbon isotope data, radiocarbon and carbon 13, on basal groundwater samples were evaluated with respect to “recharge reference” values. The latter were established on the basis of isotope analyses of water samples obtained from inland sources, such as tunnels tapping high-level dike compartments or wells located close to the mountains. Tritium data on basal groundwater samples were evaluated with respect to values for local rainfall and the recharge reference. Radiocarbon dating was used as an index of age to identify those groundwaters whose underground transit or residence times are in excess of about 200 years. Radiocarbon and tritium were used to identify young water, less than 20 yr old, through the detection of artificially high radiocarbon and tritium activities resulting from atmospheric testing of nuclear weapons during the past two decades. Underground residence times of basal waters in the Kalihi, Beretania, and Moiliili systems are quite long compared to the residence times of the other systems. Rain water infiltration in regions of high elevations located far inland is a definite source for most of the recharge to these systems. Basal water in the Waialae system has a short residence time compared to the other Honolulu systems. Moanalua basal waters were not uniform in their isotopic and chemical characteristics and indicated very long as well as very short residence times. Basal water in the western, inland portion of the Pearl Harbor system is similar in underground residence time to that in the Kalihi, Beretania, and Moiliili systems but water in the eastern and seaward portions is characterized by short residence times and, in many cases, the presence of young water. Many regions in this basal water system and, in particular, the eastern part, show the presence of transition-zone water, return irrigation water, and caprock-type water, either singularly or in some combination. Simple mixing models utilizing several suitable chemical parameters made it possible to determine the possible origins of water present in the discharge of a selected source or the presence of a particular type of water in the discharge of several sources located within a few miles of each-other.


Technical Report No. 128
TREATMENT OF MILILANI STP EFFLUENT FOR DRIP IRRIGATION OF SUGARCANE

Edward Liu and Reginald Young
August 1980

ABSTRACT
The secondary effluent of the Mililani STP is intended for use in the drip irrigation of sugarcane. The relative success of this waste water reuse application is affected by the concentration of suspended solids in the sewage effluent. Chemical coagulation, dissolved air flotation, and granular media filtration were studied in the laboratory to determine the most cost-effective means of obtaining a sewage effluent with a suspended solids content similar to that of the water from Waiahole Ditch presently used in drip irrigation. Of the three methods tested, granular media filtration with anthracite coal-silica sand media at a flow rate of .00l 7 m^3/s/m^2 (2.5 gpm/ft^2) was a cost-effective method of producing a sewage effluent with suspended solids concentration in the range of that found in Waiahole Ditch water during dry weather. Model laboratory testing shows that application of this sewage effluent will not adversely affect the type of filter media used in drip irrigation. Preliminary analysis of the residual solids distribution found in the sewage effluent after this posttreatment shows that failure of the drip irrigation system due to excessive plugging should not be a problem. The estimated annual cost of this treatment system is $147,000 based on a 0.16-m^3 /s (3.6-mgd) flow, or $40,830/mgd.


Technical Report No. 127
URBANIZATION-INDUCED IMPACTS ON INFILTRATION CAPACITY AND ON RAINFALL-RUNOFF RELATION IN AN HAWAIIAN URBAN AREA

Edwin T. Murabayashi and Yu Si Fok
September 1979

ABSTRACT
The effect of urbanization on infiltration on rainfall-runoff relations was investigated at Mililani Town, Oahu, Hawaii, a residential community. The double-ring method determined the mean constant infiltration rate to be 0.298 cm/min (7.03 in./hr) under preurban, long-abandoned, and overgrown pineapple field conditions. Following the transitional grubbing and lot-shaping operations, the rate slowed respectively to 0.126 cm/min (2.98 in./hr) and 0.22 cm/min (0.51 in./hr). The rate rose slightly to 0.050 cm/min (1.18 in./hr) under lawn, the new permanent cover. There was no significant difference between recreational and nonrecreational lawns. Incorporated in these results are unmeasurable quantities of lateral flow through the porous soil under original and grubbed conditions. Based on the data, however, the constant infiltration rate is reduced 83% after urbanization. For single-family residential areas the impermeable area overlaid by paving and buildings was 57% of the total surface area; for town houses it was 64%. Based on the experimental data for single-family residential areas, the combined effect of reduced soil infiltration and accrued impermeable surface area is estimated to reduce infiltration opportunity 10 to 1 after urbanization. Or, there may be as much as 93% reduction in infiltration after urbanization, depending on whether rainfall frequency, intensity, and duration exceed infiltrative capacity. The impact of urbanization was evaluated with a digital computer using the St. Louis Heights Watershed Model (modified ILLUDAS) with field measured rainfall-runoff relations as the basis for verification. When pervious lawn surface is substituted for impervious areas as inputs, the peak runoffs are much less than those simulated with existing impervious lands. The reduction in peak runoff from one selected storm is estimated at 79% of the observed peak.


Technical Report No. 126
GROUNDWATER RESOURCES OF KWAJALEIN ISLAND, MARSHALL ISLANDS

Charles D. Hunt Jr. and Frank L. Peterson
January 1980

ABSTRACT
To evaluate the long-term sustainable yield of the Kwajalein groundwater body, and also to investigate methods of optimum development of this resource, a total of 23 observation wells was constructed, from which the thickness, areal extent, and quality of the Kwajalein groundwater lens was monitored. During the past year, freshwater storage in the lens has averaged 1.02×106 m3 (270 mil gal) and has fluctuated more than 20% in response to recharge and discharge events. Because of the short period of record presently available and the large seasonal fluctuations, it has not been possible to determine if long-term changes in lens storage are occurring, and this can be determined only after a longer period of data becomes available. Recharge was also evaluated and during the July 1978 to June 1979 period, recharge to the fresh groundwater lens was estimated to be 8.93 x 105m3 (236 mil gal) which is 52% of the precipitation during this period. In addition, the areal distribution of recharge was found to be quite uneven with some areas adjacent to paved surfaces receiving recharge at rates as much as four times greater than other areas. A concentrated effort was made to evaluate sustainable yield; however, the length of record.presently available is simply too short to provide an accurate measure of sustainable yield for the Kwajalein groundwater body. It appears almost certain, however, that sustainable yield is greater than the present rate of annual pumpage (1.25 x 105 M3 [33 mil gal]) during the 1978-1979 pumping year), and rough estimates indicate that it may exceed 1.89 x 105 M3/yr (50 mil gal/yr). To more precisely define the Kwajalein sustainable yield, it is recommended that the lens monitoring program established during this study be continued for at least the next few years.


Technical Report No. 125
NUMERICAL MODELING OF LIQUID WASTE INJECTION INOT A TWO-PHASE FLUID SYSTEM

Stephen W. Wheatcraft and Frank L. Peterson
August 1979

ABSTRACT
The injection of liquid wastes into a groundwater environment saturated with density-stratified fluid is simulated by a finite-difference numerical model. The fluid transport equation is simultaneously solved with the convective-dispersion equation for salinity. The migration of the injected liquid waste effluent is then tracked by solving a second convective-dispersion equation for an ideal tracer dissolved in the effluent. The convective-dispersion equation for the ideal tracer is solved with the flow velocities obtained from the simultaneous solution of the fluid transport and the salinity convective-dispersion equations. The equations are solved for the two-dimensional case of a line of inj’ection wells set close together parallel to the coastline. Total length of the line of injection wells is considered to be much longer than the distance to the ocean so that any vertical cross section taken normal to the coastline will appear the same. Results are presented in a timeseries of contour maps in the vertical plane: one map for each time-step, with lines of equal concentration for the salinity (isochlors); and the effluent tracer (isopleths). The more concentrated effluent is found to migrate vertically upward around the injection well due to buoyant force, while dilute effluent solutions migrate horizontally, displaying very little buoyant rise.


Technical Report No. 124
ECOLOGICAL RESPONSE TO RELAXATION OF SEWAGE STRESS OFF SAND ISLAND, O’AHU, HAWAI’I

Steven J. Dollar
July 1979

ABSTRACT
The largest domestic sewage outfall in Hawai’i discharged 3 m^3/s (62 mgd) of raw sewage in 10 m of water approximately 1 000 m off Sand Island, O’ahu, from 1955 to 1977. Results of an ecological field study of epibenthic communities in proximity to Sand Island conducted in 1975 and 1979 show clear patterns of community change associated with both sewage impact and relaxation of this stress; negative community effects attributable to sewage input decreased, and degree of recovery of community structure increased with distance from the point source of discharge. Sewage discharge had an impact up to 5 800 m west and 1 900 m east of the outfall. This elliptical area of influence is asymmetrical to the west due to the prevailing current pattern which carried the sewage-laden plume to the southwest. Following sewage abatement two distinct zones of impact are distinguished by the degree of physical degradation of the benthic reef structure. A high impact zone extending some 500 m east and 1000 west of the outfall is now characterized by a complete biochemical reduction of the reef structure to a pitted, flat carbonate pavement covered presently with sediment-bound algal turf and few benthic faunal colonizers. In the zone of intermediate impact the old reef framework is largely intact, though devoid of most living corals. Instead, a veneer of encrusting coralline algae covers most of the reef framework. Patterns of occurrence and diversity of reef fish show characteristics of response to sewage stress similar to attached invertebrates except that the area of influence is of much smaller extent.


Technical Report No. 123
HAWAIIAN WASTE INJECTION PRACTICES AND PROBLEMS

Susan Petty, Frank L. Peterson
January 1979

ABSTRACT
In recent years in Hawaii numerous shallow waste injection wells, constructed for the disposal of domestic sewage effluent, have failed to operate as designed or desired. in the course of this study a field reconnaissance of all the known waste injection wells on O’ahu and Kaua’i, and approximately half of those on Maui, was made and their methods of operation and injection problems evaluated. The results of this study indicate that injection well problems are primarily due to physical and biological, and probably to a much lesser extent, chemical clogging phenomena at the well face. The clogging in a large part results from improper treatment plant operation, improper injection well operation and maintenance, and poor well site selection. improper well construction practices also contribute to a much lesser degree. Furthermore, the results of this study indicate that inadequate data collection, both prior to and after injection has begun, makes early detection and solution of the injection problems more difficult. Recommendations for more adequate data collection and treatment plant and injection well operation and maintenance are made which hopefully will avoid or at Least alleviate many of the injection well problems encountered in this study.


Technical Report No. 122
ECOLOGICAL OBSERVATIONS OFF THE MOKAPU, O’AHU, OCEAN OUTFALL A POST-INSTALLATION STUDY

Anthony R. Russo, Steven S. Dollar, E. Alison Kay
February 1979

ABSTRACT
An ecological study of the benthic and fish communities at Mokapu, Oahu, was completed in the summer of 1978 approximately 1 yr subsequent to the installation of a submarine outfall by the City and County of Honolulu. Data were obtained from five transects between Mokapu Point on the northeastern tip of Oahu to Alala Point, approximately 6 034 m (3.75 miles) south, at depths of 6 to 24 m (20-80 ft). This study is subsequent to an initial survey completed in 1975 prior to outfall construction.

Results show little or no effect from the operation of the outfall on the benthic and fish communities. There are not significant differences in the abundance, diversity, or composition of fishes from 1975 to 1978 except at the outfall site where new substrate was formed by construction. Between the 1975 and 1978 studies there are some differences in coral species cover indices, which are attributed to patchy substrate distribution rather than stress from the sewer outfall. Differences in species composition and distribution of micromolluscan assemblages may also be explained, at least in part, by patchy distribution of the substrate.


Technical Report No. 120
THE ENFORCEMENT OF CONSISTENCY IN HAWAIIAN WATER RIGHTS: AN INTRODUCTION TO ROBINSON v. ARIYOSHI

Williamson B.C. Chang
June 1978

ABSTRACT
One of the most critical questions regarding the future of water regulation in Hawaii is the validity of the Hawaii Supreme Court’s decision in the landmark case of McBryde Sugar Co. v. Robinson. In that case, the state supreme court overturned the assumption that surface waters in Hawaii could be privately owned. To the parties involved in the litigation, the decision came as a surprise and upset the basis for their claims to waters of the stream. As a result, the parties sought to have the results of the state supreme court decision nullified in federal court. Their efforts were successful, and in October 1977, the federal district court voided the state supreme court decision. This article challenges the validity of the federal court’s decision. The question presented before the federal court was a novel and unique one. The article discusses three models for resolving the problem and discusses an important distinction between the function of courts in declaring law and enforcing their judgments.


Technical Report No. 119
MESOSCALE STRUCTURE OF HAWAIIAN RAINSTORMS

Thomas A. Schroeder
September 1978

ABSTRACT
Three significant Hawaiian rainstorms were analyzed using conventional meteorological data and photographs from the Synchronous meteorological Satellite (SMS-2). The impact of the satellite on analysis and forecasting was evaluated. Gridding inaccuracies and the distinctive nature of Hawaiian rains limit the impact of the satellite to the scale of synoptic analysis. The storms studied illustrate the range of Hawaiian flood-producing systems and the limitations of the detection network. The most important meteorological determinant of flood location is the low-level wind direction. Forecast and detection capabilities are evaluated in terms of developments in the coterminus United States, and it is concluded that the absence of meteorological radar in Hawaii inhibits significant progress.
Contingency indices (CI) were computed for 103 rain gages in the Hawaiian islands. Results are presented in matrices of CI and in individual island maps on which Cls are plotted and analyzed relative to representative stations. The secondary CI maximum with increasing station separation, which has been attributed to spacing of convective updrafts, does not appear in Hawaiian examples. Orography dominates the CI patterns which resemble isohyets. The analysis was extended to interisland comparisons using representative windward and leeward stations. CIs decrease with distance in both samples but more so for windward (trade wind) stations.


Technical Report No. 118
A CLIMATOLOGY OF MOUNTAIN FOG ON MAUNA LOA HAWAII ISLAND

James 0. Juvik, Paul C. Ekern
June 1978

ABSTRACT
This study of the mountain cloud and fog regimes on the windward and leeward slopes of Mauna Loa, Hawai’i Island (1) develops a standardized louvered-screen, fog-catchment gage; (2) develops an indirect approximation method for estimating average droplet sizes during precipitation episodes and for separating the rainfall and fog components; (3) establishes an extensive fog sampling network on the windward and leeward slopes of Mauna Loa; and (4) develops an original computer program for detailed temporal and spatial analyses of rainfall, fog, and wind parameters.
An analysis of data for the 1974 to 1976 period yielded the following conclusions: (1) a well-defined fog belt exists on windward Mauna Loa in the altitudinal zone between 1500m to 2500m with fog catchment amounts as great as one-half the rainfall, or about 750m; (2) mountain fog on leeward Mauna Loa increases with elevation up to at least 2 000 m, with fog amounts equivalent to one-fourth the rainfall, or about 250 mm; (3) seasonal and altitudinal patterns in fog frequency and catchment amounts are related to the dynamic interaction of the tradewind field (particularly the tradewind inversion), the local land/sea breeze regime, and rainfall; (4) mountain fog appears to be a significant factor in the water balance of mountain ecosystems on Mauna Loa; and (5) the potential for large-scale mechanical recovery of fog water may exist for selected locations on Mauna Loa.


Technical Report No. 117
AN AUTOMATIC HYDRAULIC STRUCTURE TO OPEN SAND PLUGS AT STREAM MOUTHS ON O’AHU

Jon K. Nishimura, L. Stephen Lau
June 1978

ABSTRACT
Numerous stream mouths on Oahu are affected by sand berm blockages which prevent free flow of storm waters to the ocean and cause the stream water level to rise rapidly; often overflowing of the stream banks and flooding of adjacent land areas result. To avoid this hazard, removal of the sand blockage prior to the arrival of peak flood flows is necessary.

An automatic hydraulic structure which utilizes early arriving storm waters to hydraulically erode the sand berm has been developed during this study.

A hydraulic model study of a 1- to 15-scale Froudian model based on a generalized O’ahu prototype stream channel was conducted to test physically the conceptual structure design. The hydraulic model structure performed effectively, causing rapid breaching of the sand berm under severe storm flow conditions. In all cases, overtopping of the sand berm, which would result in high stream stages and possible flooding, was avoided.
Design recommendations and modifications have been developed to permit proper application of the structure to various stream mouth conditions.


Technical Report No. 116
ROTATING DISC SEWAGE TREATMENT SYSTEM FOR SUBURBAN DEVELOPMENTS AND HIGH-DENSITY RESORTS OF HAWAII

Garry T. Griffith, Reginald H.F. Young,
Michael J. Chun
May 1978

ABSTRACT
A large-scale pilot rotating disc treatment system was tested at the City and County of Honolulu Pacific Palisades Municipal Wastewater Treatment Facility, to evaluate its treatment effectiveness and capabilities, and to provide design and operation criteria in treating domestic waste water in Hawaiian and tropical climates. The system included primary clarification and sludge storage facilities, and a 0.55 m (1.8 ft) disc diameter, 20.9 M2 (225 ft2) four-stage rotating disc treatment unit. The test unit was tested at four hydraulic loadings of 0.09 to 0.27 m3/day/m2 (2. 25-6. 7 gpd/ft2). Peripheral rotational disc speed was constant at 0.3 m/s (1.0 fps) and waste water temperature was 27oC to 28oC during the study.

At hydraulic loadings of 0.09 to 0.27 m3/day/M2 (2.25-6.7 gpd/ft2) of disc area, the test unit achieved respectively 94 to 82% overall removal of carbonaceous BOD5 and 94 to 82% overall removal of suspended solids when treating degritted raw domestic waste water. This yielded effluent concentrations of 12 to 32 mg/l BOD5 and 7 to 21 mg/l suspended solids. Sludge production from the disc section was 0.40 to 0.50 mass units sludge produced per mass unit BOD5 removed in the disc section.

Low maintenance requirements, low power consumption, and resistance to the effects of hydraulic surges make the rotating disc process very attractive for package plant installations in Hawaii. In-place equipment cost for rotating disc package systems treating sewage volumes of 94.5 m3/day (25,000gpd) and 378 m3/day (100,000 gpd) were estimated to be about 10% higher than for extended aeration and high-rate activated sludge package systems. However, the total annual cost over a 20-yr period was respectively about 14% and 20% lower for the rotating disc package systems than the extended aeration and high-rate activated sludge package systems.


Technical Report No. 115
REFRACTORY ORGANIC COMPOUNDS IN TREATED EFFLUENT AND THEIR REMOVAL BY SOIL, MILILANI, O’AHU, HAWAII

Charles Fischer, Richard E. Green,
Nathan C. Burbank, Jr.
December 1977

ABSTRACT
Increased water consumption on O’ahu has encouraged the use of treated sewage effluent for irrigation. This study seeks to identify organic compounds in treated effluent and to determine if such compounds are adsorbed by soil so that the groundwater is not adversely affected.

XAD-2 resin is used to extract and concentrate trace organic compounds in treated effluent. Electron capture gas chromatography and combined gas chromotography-mass spectrometry (GC/MS) indicate that some of the organic compounds in the treated effluent are chlorinated. Gas chromatography tests also confirm the presence of naphthalene and bromobenzene in the treated effluent.

Organic compounds which could be detected by electron capture gas chromatography data are effectively removed by the Lahaina soil when the treated effluent is applied as irrigation water to a sugarcane field. On the other hand, GC/MS results indicate that the Lahaina soil only partially adsorbs organics, such as paraffins and steroids. Laboratory measurements of adsorption of organic compounds from effluent do not adequately represent the extent of adsorption measured in the field.


Technical Report No. 114
DIGITAL SIMULATION AND EVALUATION OF STORM DRAINAGE SYSTEMS: ST. LOUIS HEIGHTS WATERSHED MODEL

Yu-Si Fok
Edwin T. Murabayashi, Sanguan Phamwon
November 1977

ABSTRACT
The adequate design of a storm drainage system depends upon the proper estimation of various peak discharges (produced from a given storm) along the drainage network. The objective of this study is the development of a digital computer model utilizing available hydrologic data obtained during 1972 to 1975 to simulate runoff from given rainfall patterns in Hawaiian urban watersheds and the development of procedures for channel flow routing through gutters and storm drains and runoff routing from pervious and impervious areas. The computer model is the result of using the kinematic wave equation, which is most suitable to steep topographic terrain such as that of the study area, to modify the overland, gutter, and sewer flow routing procedures of the well-known Illinois Urban Drainage Area Simulator (ILLUDAS) model. Available infiltration data were used to modify the infiltration process.
Examples of the system capacity design and evaluation, and computer programs for the application of this simulation model are presented for users’ adaptation.


Technical Report No. 113
HANDBOOK-INDEX OF HAWAII GROUNDWATER AND WATER RESOURCES DATA EXTRACTED FROM REPORTS OF THE WATER RESOURCES RESEARCH CENTER, UNIVERSITY OF HAWAIIVOLUME I

John F. Mink
September 1977

ABSTRACT
The research of the Water Resources Research Center covers all aspects of water resources investigations, in the course of which considerable new significant data are generated and older data reevaluated. These data are included in the basic technology transfer documents of the Center, the Technical Reports. To make it easier for the user-the engineer, hydrologist, environmentalist-seeking specific information from the nearly 100 reports published, the transfer of information is made in this Handbook-Index. The transfer of data sets from original publications is restricted, in this first volume, to groundwater matters; however, an index of all significant water resources data sets in the Technical Reports is also included as a separate section. The groundwater data sets are listed in six broad categories: aquifer characteristics, physical properties of basalt, hydraulic and physical properties of basalt, hydraulic and physical properties of soils, regional geophysical features, geochemistry, and radioactive dating. The Index of significant data sets of all water resources matters is divided into the following categories: geophysics, geohydrology, groundwater hydraulics, surface water hydrology, sanitary engineering-waste water, radioactive dating, geochemistry of water, groundwater pollution, surface water pollution, ocean and coastal pollution, desalting, hydrometeorology, and systems.


Technical Report No. 112
DIURNAL VARIATION IN RAINFALL AND CLOUDINESS

Thomas A. Schroeder, Bernard J. Kilonsky, Bernard N. Meisner
July 1977

ABSTRACT
Maps of diurnal rainfall patterns based on hourly rainfall records are presented for the six major Hawaiian islands. The resulting rainfall distributions demonstrate the complexity of the interaction between trade winds and large islands. Distributions for windward stations on the low islands have early morning maxima common to the tradewind rainfall over open oceans. Mesoscale circulations and moisture extraction by windward mountain barriers modify the oceanic pattern, particularly on the high islands. Patterns on Hawai’i shift from nocturnal maxima on windward coasts to pronounced daytime maxima on the leeward coasts. At higher windward elevations on Mauna Loa and Mauna Ke’a, the pattern shows afternoon peaks as contrasted to nocturnal maxima at windward coasts, such as at Hilo. First harmonic R2 approached .90 at windward stations on small islands and in regions of strong mesoscale circulations. For the largest island., Hawaii, R2 exceeded .60 for all stations examined.

Hourly mean cloudiness maps for a two-week period in July 1976 are presented for Hawaii island based on SMS-2 geostationary satellite images. Tests verify the subjective analysis procedure, particularly when applied to the visible images. Although rainfall over most of the island was below normal, rainfall frequencies were not, indicating that observed cloudiness was typical of summer conditions. Stations were geographically grouped. Windward coastal stations have small diurnal cloudiness variations but pronounced nocturnal rainfall maxima. Higher elevation windward stations have larger cloudiness variation but smaller rainfall variation, while leeward stations have large and pronounced variations in both rainfall frequency and cloudiness, with maxima occurring in the late afternoon.


Technical Report No. 111
RECYCLING OF SEWAGE EFFLUENT BY SUGARCANE IRRIGATION: A DILUTION STUDY OCTOBER 1976 TO JUNE 1977 PHASE II-A

L. Stephen Lau, Paul C. Ekern, Philip C.S. Loh, Reginald H.F. Young, Gordon L. Dugan
August 1977

ABSTRACT
Phase II-A is a project that is an extension of a recently completed 4-yr project (July 1975) entitled “Recycling of Sewage Effluent by Irrigation: A Field Study on Oahu,” hereinafter referred to as Phase I. The main purpose of Phase I was to apply secondarily-treated sewage effluent from the Mililani STP to thirty 0.04-ha (0.1-acre) test plots of sugarcane located in Oahu Sugar Company’s (OSC) Field No. 246 in central Oahu, Hawaii. The results of this study showed that sewage effluent applied for irrigation during the first year and Waiahole Ditch water the second year of the 2-yr sugarcane crop cycle increased the sugar yield by 6% over control plots, whereas, sewage effluent applied during the full 2-yr cycle reduced the sugar yield by 6% below the control plots. Sewage-borne viruses and coliform bacteria in the applied sewage effluent were inactivated within the shallow root zone; and salts, including nitrogen, did not appear to leach below the root zone in any greater quantities than that of the companion ditch-irrigated plots.
The results of Phase I appear promising in terms of increased sugar yield, an additional irrigation water source, and alleviation of a sewage effluent disposal problem; however, it is not presently considered economically feasible to construct and maintain a separate ditch water and sewage effluent field distribution system, thus, the question arises as to the optimum dilution of sewage effluent with ditch water for a single field distribution system so that sugar yield will not be decreased and hopefully increased over present plantation practices.

The Phase II-A portion of the project attempts to determine the dilution necessary for an optimal balance of water disposal and sugar yield. Secondary objectives of the project are to monitor the quantities of nitrogen leaching past the root zone and continued monitoring of sewage effluent for the presence of human enteric viruses. The reporting period for this progress report is from October 1976, when the sugarcane was planted in the test plots, to June 1977.
The same 30 test plots and sugarcane variety (Hawaiian variety 593775) as used in Phase I were incorporated in Phase II-A. Five irrigation treatments for the 2-yr cycle with six replicates in a randomized block design were: (1) ditch water, (2) 12.5%, (3) 25%, (4) 50% effluent diluted with ditch water, and (5) effluent the first year and ditch water the second year. Irrigation rounds of up to 10 cm (4 in.) were applied bi-weekly, and tensiometers in selected test plots monitored water stress conditions. Representative soil samples were collected and analyzed shortly after sugarcane planting commercial fertilizer applications of N, P, and K to the teat plots were completed in June 1977.
Four crop logs were made on sugarcane growth in the test plots. The physical appearance of that growth was very good; however, the relatively low K-H20 index and the high total sugars from the crop log indicate a possible growth imbalance. Rainfall during this period, due to a very dry winter, was nearly one-half of normal, whereas, evaporation was more than 50% above normal.

Secondary effluent from the Mililani STP is typical of domestic sewage, although it has a higher BOD5 than experienced during Phase 1. The effluent is monitored on a routine basis at the STP, and also when the test plots are irrigated. Soil leachates are collected during each irrigation from representative plots through 5-cm (2-in.) diameter by 1.52-m (5-ft) long porous plastic “Porvic” samplers placed horizontally in the subsoil beneath the root zone. The concentration of nitrogen in the leachates collected beneath the root zone fluctuates with fertilizer applications, but after fertilizer applications were completed, increases with the higher percentage of effluent in the irrigation water were observed.


Technical Report No.110
GROUNDWATER RECHARGE AND COASTAL DISCHARGE FOR THE NORTHWEST COAST OF THE ISLAND OF HAWAII: A COMPUTERIZED WATER BUDGET APPROACH

Brian Y. Kanehiro,Frank L. Peterson
July 1977

ABSTRACT
The basic objectives of this study were to determine the average annual recharge to the groundwater body and the fresh groundwater discharge at the coastline, as well as the aquifer characteristics for an and area located on the northwest coast of Hawai’i island between Kiholo Bay in the south and Puako in the north, and encompassing the land from the coast to approximately the 762-m (2500-ft) elevation level. Of equal importance was the development of methodologies, namely, a computerized water budget and groundwater tidal analyses to calculate these quantities.
The probable recharge to the groundwater body in this region was computed to be 143.83 x106 M3/yr (38 bil gal/yr). Due to the lack of hydrologic data for the area, a range of values was determined, with the maximum average annual recharge being 264.95 x106 M3 (70 bil gal) and the minimum being 719.15 x105 M3 (19 bil gal). Since there are 26 km (16 miles) of coastline in this area, this implies a probable average daily flux of 15,006 m3/km (6.38 mil gal/mile) of coastline.

Three different calculations were obtained for the hydraulic conductivity of the groundwater aquifer in the coastal region: two by tidal analysis, and a third based on the coastal discharge as determined by the water budget. The Werner and Noren method of tidal analysis gave an average value for Kz (hydraulic conductivity times average saturated depth of aquifer) in the vicinity of ‘Anaeho’omalu Bay of 585,270 M2/day (6.3 x 106 ft2/day); the method by Cox gave a value for K in the same area of 1,027 m/day (3,369 ft/day). The coastal flux method gave a value for K of 2,771 m/day (9,092 ft/day).


Technical Report No. 108
WELL INJECTION INTO A TWO-PHASE FLOW FIELD: A HELE-SHAW MODEL INVESTIGATION

John A. Williams
May 1977

ABSTRACT
A Hele-Shaw model was employed in conducting preliminary studies of waste water injection into a fresh-saline water system. Three different field conditions were simulated: injection under static conditions, injection into an ambient flow field without a fresh-saline water interface, and injection into an ambient flow field with a fresh-saline water interface. Both single and double-well injections were studied for the latter case of injection in the presence of an interface. The density of the saline water was 1.026 g/cm3 for the majority of the tests while that of the injected fluid was 1.0005 g/cm3.

The test results indicate that when injection is below the fresh-saline water interface, the injected fluid, under the action of the buoyant forces, rises through a relatively narrow, vertical channel to the interface and then spreads laterally along that surface. The distance the injected fluid migrates upstream from the point of injection increases with the distance below the interface at which injection takes place. Consequently, injection at or above the interface appears to be preferable to injection below the interface from an economic as well as a pollution standpoint.
The general behavior of the injected-ambient flow field as observed in the two-dimensional Hele-Shaw model is consistent with that observed in a three-dimensional, sand-filled, hydraulic model.


Technical Report No.109
DRIP IRRIGATION OF SUGARCANE MEASURED BY HYDRAULIC LYSIMETERS, KUNIA, OAHU

Paul C. Ekern
June 1977

ABSTRACT
The daily water budget of drip-irrigated sugarcane at Kunia, Oahu, was measured in large hydraulic load cell lysimeters. The 10-mo plant crop period was extrapolated to 109 cm (43 in.)/12-mo water use. Extrapolation from the full-canopied period (leaf area index 4) gave only 99 cm (39 in.)/ 12 mo of water use. The initial 12 mo of the second ratoon had 128 cm (50.5 in.) of evapotranspiration-a 2-yr cycle of water use would be 278 cm (109.5 in.) or 140 cm (55 in.)/12 mo. Drip irrigated cane used an average 79% of the 173 cm (70 in.) of annual class A surface pan evaporation or 70% of the evaporation from a pan elevated to 1.52 m (5 ft) or one kept at cane canopy height. This lower ratio between cane use and pan evaporation would make water use 15% less from drip irrigated as compared to sprinkler irrigated fully canopied cane. The average portion of sunlight energy equivalent to cane evapotranspiration was 45%, but ranged from 25% immediately after planting to as great as 60% during periods of strong positive advection with full cane canopy. Further economies in water use with drip irrigation resulted from the much greater uniformity of distribution of water with drip as opposed to sprinkler irrigation. During rainy periods, percolate was not curtailed and evapotranspiration was as little as 20% of the applied rainfall and irrigation. However, during the dry summer months, evapotranspiration was essentially equal to the combined rainfall and drip irrigation. Salt rings formed at the perimeter of the 0.61-m (2-ft) diameter surface zone wetted around each Submatic dripper. The maximum percolate rates through the 1.52-m Molokai Oxisol profile were 5 cm/day (2 in./day), even with water ponded on the surface. Essentially none of the 356.73 kg/ha (318 lb/acre) of nitrogen applied as fertilizer was removed in the deep percolate. Chloride content of the percolate which had increased from 150 mg/l to over 700 mg/l during the period of sprinkler irrigation underwent a parallel increase under drip irrigation after the initial flush from the heavy rainfall in January 1971. Silica levels of 65 mg/l in the irrigation water were reduced to 20 mg/l in the percolate.


Technical Report No. 107
A LABORATORY STUDY OF WASTE INJECTION INTO A GHYBEN-HERZBERG GROUNDWATER SYSTEMUNDER DYNAMIC CONDITIONS

Duane L. Heutmaker, Frank L. Peterson, and Stephen W. Wheatcraft
March 1977

ABSTRACT
Injection of wastes into a Ghyben-Herzberg groundwater system presents unique problems because the waste effluents are normally injected into the salt or brackish water underlying the fresh Ghyben-Herzberg lens. Because the waste water commonly has approximately the same density as fresh water, in addition to any ambient groundwater flow effects, a buoyant uplift is produced which causes the injected waste to move upward and outward from the injection point as a buoyant plume.

A laboratory sand-packed hydraulic model was used to study the mechanics of buoyant plume movement, and the entrainment of salt water by the plume. Simulated waste effluent was injected into a density-stratified aquifer system under dynamic groundwater conditions, and the effects on plume mechanics of varying several different injection parameters, such as injection depth and rate, type of injection source, strength of the ambient flow field, and density of ambient receiving water, were observed.

In every experiment conducted during this study, a buoyant plume of injected effluent, which was clearly distinct from the resident aquifer liquids, formed and rose vertically into the lower portion of the freshwater lens, where it was subjected to the freshwater flow field and migrated downgradient with the fresh water, still keeping its identity as a distinct plume of injected effluent.

Three of the injection parameters exerted significant control on the movement of the injection plumes. The rate of effluent injection and the strength of the ambient freshwater flow field significantly influenced both the vertical and upgradient dimensions of the plumes, and also appeared to influence downgradient mixing of the plume with the ambient fresh water; and the depth of effluent injection, with respect to the relative density of the resident liquids, influenced the upgradient migration of the plumes.

Although there was some initial evidence of salt water entrainment within the salt zone injection plumes, it was a transient phenomenon, and little evidence of salt water entrainment was observed once the plumes reached steady-state conditions. Downgradient dilution of the effluent plumes by the ambient fresh water was apparent, however, and increased with downgradient distance from the injection well.


Technical Report No. 106
WATER QUALITY OF NORMAL AND STORM-INDUCED SURFACE WATER RUNOFF: KANE’OHE BAY WATERSHED, OAHU, HAWAII FEBRUARY 1974 TO MARCH 1975

Gordon L. Dugan
Watershed Management Unit
HESL Technical Report No. 7
February 1977

ABSTRACT
The Hawaii Environmental Simulation Laboratory (HESL), since its establishment in the spring of 1971, has attempted to simulate some of the consequences of alternative land-use economic decisions which include, as one of its major parameters, the effects of proposed land-use changes on the quantity and quality of water within the watershed and its succeeding watershed(s) and/or receiving water. The scope of the report, which encompassed stream water quality monitoring under both normal and storm-induced conditions within drainage areas that are subjected to different land management practices, was primarily based on a 12-mo routine water quality sampling and analysis program by HESL, for five stream sites in the Kaneohe Bay watershed, and a companion storm-induced stream water runoff 5-mo sampling program during the winter season at one of the stream sites. In general, the results of the study indicated that: the constituent concentrations were related to flow rather than to the time phase of the storm (stream) runoff; the sediment and particulate carbon, nitrogen, and phosphorus increased directly with flow; and the influence of the quality of the rain become greater with increased flow, as evidenced in reduced concentrations of silica dioxide, conductivity, and nitrite and nitrate nitrogen. Dissolved organic and ammonium nitrogen, and dissolved organic and phosphate phosphorus tended to decrease slightly, but in general did not present an apparent particular pattern.
Through the use of HESL investigations and technique developments, supplemented with values reported in the literature, a planner-decision maker should have the necessary tools for the compilation of adequate data for predicting water quality and quantity changes due to determinations of land-use alterations.


Technical Report No. 105
HYDROLOGIC AND ECOLOGIC INVENTORIES OF THE COASTAL WATERS OF WEST HAWAII

Sea Grant College Program, Years 07-08
ASSOCIATE INVESTIGATORS
E. Alison Kay
L. Stephen Lau
Edward D. Stroup
Stephen J. Dollar
David P. Fellows
PROJECT PRINCIPAL INVESTIGATOR
Reginald H.F. Young
Sea Grant Cooperative Report UNIHI-SEAGRANT-CR-77-02
April 1977

ABSTRACT
The goal of this project was to provide information to the County of Hawaii and to the state for the intelligent management of the marine and coastal resources of West Hawaii, particularly the South Kohala and North Kona areas. This was accomplished through compilation of inventories of biological, hydrological, and some oceanographic data for four selected sites, Puako, Waiulua, ‘Anaeho’omalu, and Kiholo bays.

Evaluation was made of existing hydrologic, geologic, oceanographic, and ecologic data in order to determine the volume and influence of groundwater discharge to coastal areas as well as the biological community structure in the near-shore waters.

Research results have yield a classification of the bays according to wave energy and groundwater intrusion. Poor circulation and high groundwater intrusion result in turbid conditions with communities of low diversity-a coastal situation suitable perhaps for a small boat harbor or marina, but undesirable for a marine park or preserve.
These results provide an excellent reference point for planning the use or development of the study sites or areas of related hydrologic and ecologic conditions. The methodology and techniques employed can be adapted for monitoring other coastal zone sites in the state.


Technical Report No. 104
SURVEY OF BENTHIC CORAL REEF ECOSYSTEMS, FISH POPULATIONS, AND MICROMOLLUSKS IN THE VICINITY OF THE WAI’ANAE SEWAGE OCEAN OUTFALL, O’AHU, HAWAI’I-SUMMER 1975

S. Arthur Reed, E. Alison Kay, and Anthony R. Russo
May 1977

ABSTRACT
A marine survey was conducted in the vicinity of the present and proposed Wai’anae sewage ocean outfall site on the southwest coast of 0’ahu, Hawaii. The survey at depths of 6 to 30 m (20-100 ft) characterized quantitatively the coral reef community, the reef fish population, and micromolluscan assemblages. Diversity indices were calculated for substrate, fish, and micromollusk. Similarity indices were computed and a dendrograph was generated for all stations.
The stations could be clustered into three distinct regions: (1) a deep-water region (18-30 m depth) with smooth hard algae-covered limestone substrate and sand, low fish abundance and diversity, low micromollusk diversity with high abundance of dialids, and low abundance of archeogastropods and rissoids; (2) a shallow-water region (6-18 m depth) with comparatively high coral cover, high fish abundance and diversity, high micromollusk diversity with low abundance of dialids and high abundance of rissoids and archeogastropods; and (3) the region along the harbor channel at Poka’i Bay where coral cover, fish abundance and diversity, and micromolluscan species abundance were distinctly different from those of other stations, indicating a probable influence by the boat harbor and channel on the benthic community. The sewage effluent has not adversely influenced coral growth in the vicinity of the outfall diffuser although increased nutrients may account for high abundance of frondose algae at this station.


Technical Report No. 103
THE EUTROPHIC POTENTIAL OF WAHIAWA RESERVOIR SEDIMENTS

Leighton W.K. Lum and Reginald H.F.Young
August 1976

ABSTRACT
In recent times the increased influx of nutrients and organic matter as a result of man’s activities into some waterways has resulted in the accelerated eutrophication of these waters. This has been found to be the case in Wahiawa Reservoir. Secondarily-treated sewage effluent discharges into the reservoir have been implicated as the primary cause of the eutrophic conditions present in the reservoir.

Studies have been undertaken and management alternatives are being considered to improve the trophic status of the reservoir. The nutrient mass balance has been determined and the source of the major portion of the nutrient influx to be from the Wahiawa Sewage Treatment Plant (STP). Corrective measures will probably be directed toward further treatment or diversion of this source.

The relative importance of in situ nutrient sources, such as N fixation and the sediment, have not, however, been determined. The eutrophication potential of the sediment and its relative importance and impact on the selection of a management alternative was the objective of this study. To ascertain this effect, sediment-water contact studies were carried out.

Sediment was incubated with four different types of water simulating aerobic and anaerobic conditions in the hypolimnion of the Wahiawa Reservoir. Samples were withdrawn periodically and analyzed for nutrients, chemical oxygen demand (COD), and other constituents. After parameters reached a steady-state, the algal growth potential (AGP) of the waters was determined.

Under aerobic conditions, the sediment tended to have an oligotrophic effect on the water. Phosphorus was adsorbed by the sediment, N release from the sediment was inhibited by the development of a surface-oxidized layer, and the COD of the water was decreased. This effect was verified by the poor AGP of the water, which was P deficient.
The sediment was found to be capable of deoxygenating dissolved 02-saturated water. Substances causing a cop were released from the sediment under anaerobic conditions and the measured COD increase was about 10 mg/l, exceeding the increase resulting from the STP effluent and other sources. The COD levels maintained verified the capability of sediments to deoxygenate saturated waters.

Under anaerobic conditions, considerable N release from the sediment occurred. The increase alone far exceeded critical levels and was attributed to the release Of NH3 (5.7 to 8.2 mg/l NH3-N) from sediments. The level of P04= in most systems -far exceeded critical Limits but particulate PO4 was generally unavailable for algal growth according to test results. Results of dissolved PO4 from the sediment occurred only in low-turbidity waters under reducing conditions. The concentration of dissolved PO4 exceeded by 3 to 4 times the critical levels established in the reservoir. The high AGP in some reactor waters was verification of the eutrophication potential of the sediment. However, considering the dilution capacity of the reservoir, the concentration of P, but no N, maintained by release from the sediment would be rendered insignificant during periods of high influx and mixing.

The loading rates for sediment N and P under anaerobic conditions were of significance when compared to established guidelines. However, the sediment was of minor importance relative to the nutrient Loading from other sources to the reservoir. Even with the removal of a majority of the nutrient inputs by diversion or further treatment of the Wahiawa STP effluent, sediment still accounted for only 18% of the N and less than 1% of the P loading to the reservoir.
Sediments were found to be able to cause or maintain eutrophic conditions in the test reactors under anaerobic conditions. However, the nutrient contribution was of minor importance relative to other sources. Corrective measures with respect to nutrients released from the sediment are not required, but stabilization of the 02 demand from substances released from the sediment may be required to improve dissolved 02 levels in the deeper portions of the reservoir.

A nutrient model of the reservoir shows that diversion of the Wahiawa STP effluent will result in a 65% reduction of N and a 46% reduction of P in the epilimnion of the reservoir. New steady-state conditions were expected to be attained within 30 days, while new steady-state conditions for the hypolimnion and sediments may require about two years.


Technical Report No. 102
NITROGEN REMOVAL FROM SECONDARY EFFLUENT BY A LABORATORY SOIL COLUMN

Gordon L. Dugan, Paul C. Ekern, and Roy T. Tsutsui
August 1976

ABSTRACT
The objective of the project was the investigation of the percolate rate and the disposition of nitrogen from a laboratory soil column when chlorinated secondary sewage effluent was applied under both continuous and intermittent loading. A 1.7-m (5.5-in.) diameter column was packed to a depth of 1.5 m (5 ft) with a well-aggregated Oxisol soil (Lahaina series). A constant head was maintained by a modified Mariotte bottle during the application of effluent. Percolate was sampled through ports at 7 depths as well as from a bottom drain.

When effluent was continuously ponded on the surface: (1) percolate rate decreased with time, (2) ammonium ions were adsorbed, (3) nitrification was suppressed, (4) denitrification occurred, and (5) the denitrification biological community required more than 2 days to develop.

When effluent application was stopped after 2 days and aerobic conditions developed, nitrification was very active within 5 days.

The solute breakthrough curve appeared well in advance of 1 pore volume and was highly skewed with an extended tail.


Technical Report No. 101
INVENTORY OF BENTHIC ORGANISMS AND PLANKTON AT MOKAPU, OAHU

Anthony R. Russo, Steven J. Dollar, andE. Alison Kay
January 1977

ABSTRACT
An inventory of benthic and planktonic marine communities at Mokapu Point, Oahu, compiled in July to August 1975, prior to the completion of an outfall and discharge of secondary sewage effluent, has been prepared for the City and County of Honolulu. Data were obtained from five transects between Mokapu Point on the northeastern tip of Oahu to Alala Point, approximately 6km (4 miles) south, at depths of from 6 to 30 m (20 to 100 ft). The area is exposed to predominant northeast tradewinds.

Coral cover ranges from 20% at the 6 m depth stations to 85% at greater depths, with the most abundant corals at depths of from 12 to 18 m (40 to 60 ft). Four species of corals dominate the survey area, Pocillipora meandrina, Porites lobata, P. compressa, and Montipora sp. Most of the stations surveyed had little or no algal cover. Standing crop of fishes and mollusks decreases from stations A through C (north to south) and increases at stations D and E (the southernmost of the transects). The dominant fish are acanthurids and chaetodontids. The dominant mollusks are gastropods, primarily the archaeogastropods Tricolia variabilis and Leptothyra rubricincta, rissoids, cerithids, and dialids. Total numbers of fish are not dependent on coral cover, but standing crop of micromollusks decreases with increasing coral cover and depth. Standing crop of net phytoplankton cells (<100u) measure 2000 to 3000 cells per cm3- but does not vary significantly with area. Macrozooplankton abundance decreases from north to south.
Transect A is distinguished by an especially high energy environment, reflected by the low standing crop and mixed species composition of micromollusks. Transect B, the proposed outfall site, is hard and flat, and mostly devoid of coral cover; very few fish were seen at this station.


Technical Report No. 100
WET-WEATHER WATER QUALITY MONITORING KANEOHE BAY, OAHU, HAWAII

L. Stephen LauReginald, H.F. Young, Stanley K. Konno, Robert J. Oldnall, and Helen H. Lee
August 1976

ABSTRACT
A water quality monitoring survey during the wet-weather seasonal period (January to June 1976) was conducted in the Kaneohe Bay area as part of the U.S. Army, Corps of Engineers Kaneohe Bay Urban Water Resources Study. The survey encompassed three principal drainage subareas, Kaneohe, Waihee, and Waikane, with both upstream and downstream monitoring stations as well as other selected stream and bay sampling points. Both grab sampling and continuous sampling were employed for the stream stations; the latter technique required the use of automatic samplers in order to monitor the runoff from a particular rainfall or storm event.

Mass emissions or stream loadings followed predictable patterns with increases from upstream to downstream stations, higher values in the more urbanized southern areas of the study area, and higher values for this wet-weather period compared to the dry-weather period. In two specific storm events for which data were obtained, the solids load and turbidity peaked before the streamflow hydrograph. Maximum chlorinated hydrocarbon pesticide levels in bay sediments were obtained off-shore from stream mouths, near the urbanized areas.

State water quality standards were exceeded in the case of bay waters for total nitrogen and total phosphorus. The phosphorous standard for most stream stations and the dissolved oxygen standard for both fresh and coastal waters was not exceeded. The total organic content was low except for high runoff events. Insufficient coliform data were obtained for statistical comparison with the state standards.

Chlorinated hydrocarbon pesticides were detected in the ng/l, range for most water samples and two bay samples contained PCB(0. 5 and 0.2 ug/l). Stream samples had higher levels of pesticides than bay samples with a distribution pattern related to degree of urbanization. Heavy metals (Pb, Cu, Zn, Cd, Hg, Cr, Ni) were detected in all bay sediments analyzed.

Urban street sweepings were collected with variations in rate of solids accumulation and concentration of nutrients, heavy metals, and pesticides. The nutrient content was principally organic nitrogen. High lead values were attributed primarily to fallout from automobile exhaust. Dieldrin, a and y chlordane, p,p-DDT, and PCP were found in the ug/l level.


Technical Report No. 99
LOW-FLOW FREQUENCY AND STOCHASTIC ANALYSIS OF IRRIGATION DITCH FLOWS FOR CENTRAL MAUI, HAWAII FINAL REPORT

Yu-Si Fok
and Clyde S. Miyasato
November 1976

ABSTRACT
The central portion of the island of Maui, state of Hawaii, suffered from droughts during the summers of 1971 to 1975, which resulted in heavy crop losses. In order to learn more about the frequency of droughts, a study of the irrigation water low-flow frequency was made during the earlier stage of this research, and a set of low-flow frequency curves for the central Maui area was prepared and presented in this report. Low-flow frequency curves can only provide the probability of occurrence of a drought in terms of a given magnitude of flow, its duration and its recurrence interval; therefore, their applicability is limited to an event basis, and the sequential characteristics of the droughts are not provided. In order to study the drought occurrence on an event-sequence basis, with the aim to explore the water manageability during a drought, a stochastic analysis of the low flows in the summer periods of the central Maui region was conducted. The methods and results of the stochastic analysis are presented in this report. Since most of the irrigation water is collected and delivered by ditches to the central Maui sugarcane fields, and among these ditches, the Wailoa ditch delivers about 90% of the summer months’ irrigation water; therefore, the Wailoa ditch monthly flow recorded by U.S. Geological Survey for 1923 to 1972 has been used for the stochastic analysis of the summer low flows. The results obtained show very little improvement from using Pearson Type III distribution against the normal distribution of the random error term in the stochastic simulation of the summer ditch flows. Four sets of summer ditch flows for the period 1974-2020 have been generated and presented for water management references.


Technical Report No. 98
WATER QUALITY MONITORING: KANEOHE BAY AND SELECTED WATERSHEDS JULY TO DECEMBER 1975

Reginald H.F. Young, L. Stephen Lau,Stanley K. Konno, and Helen H. Lee
May 1976

ABSTRACT
A water quality monitoring survey of three drainage subareas in the Kaneohe Bay watershed and selected sites in the bay was conducted between July and December 1975 to ascertain the dry-weather quality baseline. The three drainage subareas were Kaneohe, Waihee, and Waikane. Upstream stations beyond any highly developed areas and downstream stations near the stream mouths were selected in order to obtain some information on the effect of development or land use on water quality. Bay stations were located off the stream mouths, over sewer outfalls in the southern sector, and in the main channels of the bay.

The results yielded patterns as expected: poorer quality in the more developed southern and central subareas compared to the northern subzero, poor quality also off the stream mouths and at the sewer outfalls in the bay. The stream monitoring results generally parallel previous studies by the Water Resources Research Center and the Hawaii Environmental Simulation Laboratory.

The State Water Quality Standards for Class AA (bay) and 2 (stream) waters were exceeded in the case of nutrients (N and P) and coliform bacteria, but were met in the case of pH and dissolved oxygen.
Loading rates, based on mean flow data and parametric concentrations for N and P compared against 1968 data, indicate a two-fold increase for the southern subzero, a lesser increase for the central subzero, and relatively little change for the northern subzero.

As expected, the bay water contained but a few parts per trillion of a chlordane, Y-chlordane, dieldrin, and PCP. The stream water samples were generally slightly higher in concentration. DDT, DDD, DDE, lindane, heptachlor, and PCB were not detected. The highest level, although low in parts per trillion of pesticides, was found in stream water draining developed land. Heavy metals, Cd, Cr, Cu, Pb, Hg, Ni, and Zn, were present in bay water in expectedly low background concentrations on the order of a few parts per billion. No gradation in heavy metal concentrations was observed in different parts of the bay. The heavy metal content in the streams was comparable to those in the bay.


Technical Report No. 97
METEOROLOGICAL ASPECTS OF THE OAHU FLOOD OF 19 APRIL 1974

Thomas A. Schroeder
UHMET 76-03
February 1976

ABSTRACT
A detailed study has been made of the severe Oahu rainstorm of 19 April 1974 and its implications for the Hawaii flood forecast problem. Conventional meteorological analyses were performed, using standard surface observations, aircraft reports, and satellite photography. Data from Oahu’s extensive recording rain gage network were analyzed to determine the mesoscale structure of precipitating cloud systems. Conceptual models of the flood-producing convective elements were then constructed.

It was found that the synoptic scale situation was one which has historically generated flooding. Fresh trade winds in the lower troposphere were combined with a trough in the upper troposphere to produce thunderstorms over Oahu. Hourly rainfall analysis revealed two centers of high rainfall. One of these centers was produced by a continuous thunderstorm. A conceptual model of a continuous thunderstorm over Oahu was then formulated.
Study of the special rain and stream gage network in Moanalua Valley showed that the current monitoring scheme of one telemetered rain gage per Valley is inadequate. Finally, a discussion of the current state-of-the-art in Hawaiian flood forecasting and monitoring is offered. It is proposed that the installation of a meteorological radar is the only viable solution to the problem of early detection of flash flood potential.


Technical Report No. 95
WATER PROBLEMS AND RESEARCH NEEDS FOR HAWAII: 1975

L. Stephen Lau
February 1976

ABSTRACT
Because of their insular subtropic and volcanic environment, Hawaii and similar regions have special water problems and study needs not duplicated in the temperate continental region. Hawaii’s water problems have also changed over the past two decades as the economic base has progressed from a primarily agricultural existence to a mixture of urban-recreation-tourism, plantation agricultural, commercial-industrial, and military and governmental activities. Existing and emerging water problems and study needs have been identified for Hawaii in a 1974-1975 joint study by the Hawaii Water Resources Regional Study and the University of Hawaii’s Water Resources Research Center. Among the nine water problem areas in water quantity, water quality, environmental impact, and water planning and management, over 20 specific study needs have been identified. The historical and recent water study association and cooperation between Hawaii and other Pacific islands, including Guam, is described.


Technical Report No. 94
WATER RECYCLING OF SEWAGE EFFLUENT BY IRRIGATION: A FIELD STUDY ON OAHU

Final Progress Report for August 1971 to June 1975
Project Principal Investigator
L. Stephen Lau
Co-Investigators
Paul C. Ekern Soil and Irrigation
Philip C.S. Loh Virology Studies
Reginald H.F. Young Water Quality Analysis
Nathan C. Burbank, Jr. Public Health Aspects
Gordon L. Dugan Data Management and
Report Preparation
July 1975

ABSTRACT
The specific project objectives were to: (1) evaluate by field lysimeters and pilot plots and augment by laboratory studies the feasibility of utilizing water reclaimed from sewage for irrigation under Hawaiian conditions; (2) assess the probable effects of surface-applied reclaimed water on groundwater quality particularly in terms of potential viral transmission and long-term buildup of solids; (3) evaluate the effects of various water quality parameters on the soil, percolation, and vegetative growth when grassland or sugarcane is irrigated with sewage effluents; (4) explore any problem in sugarcane culture, either in technology or in crop quality that might be involved in the irrigation of sugarcane with water reclaimed from sewage.

The central Oahu project site area is located near the Mililani Sewage Treatment Plant (STP) which, in 1975, received approximately 3217 m3/ day (0.85 mgd) of essentially domestic sewage from the nearby expanding Mililani Town development. The STP utilizes the Rapid Bloc activated sludge process (secondary treatment) that achieves a suspended solids and BOD5 removal rate that averages 90%. The location of the project site was chosen in part because the adjacent field soils are of the Oxisol order similar to that on which approximately 90% of the sugarcane cultivated under irrigated conditions on Oahu is grown. The general project site area receives an average annual rainfall of approximately 102 cm (40 in.), and is situated at an elevation approaching 152 m (500 ft).

The research activities were grouped into three major areas: soils and irrigation, viral analysis, and water quality analysis. In general, the values of guideline chemical parameters for the Mililani STP effluent are below the maximum value for irrigation of sensitive crops. Pesticides and heavy metal concentrations were either below the level of concern or level of detectability. Nitrogen was given special emphasis for several reasons: its use as a major component of most fertilizers; its known adverse effect (lowered sugar yields) on matured sugarcane; its essential solubility in the nitrite and nitrate form; its relationship in concentrations above 10 mg/l as N to methomoglobinemia, the disease of infants; and its potential rote in the eutrophication of open bodies of water receiving excessive nitrogen loads.
Commencing in August 1971, the project activities consisted of: the installation of field grass-sod, bare soil, and field lysimeters at the Mililani STP; coordinating laboratory facilities and analytical capabilities for determining the constituents in water, waste water, and soils; development of virus culturing and assaying techniques under field conditions, and studying the application of secondary effluent to maturing sugarcane in OSC Field No. 240, located approximately 3.2 km (2 miles) from the Mililani STP. The results of these studies helped establish procedures and guidelines for the principal focus of the project, the sequential application of sewage effluent, ditch water, and combinations thereof, to sugarcane in 30 test plots with uniform areas of 0.04 ha (0.1 acre) each in the newly planted (February 1973) OSC Field No. 246, located approximately 1.6 km (1 mile) from the Mililani STP. The test plots were divided into three basic irrigation schemes of ten plots each: A, B, and C. Plots “A” were scheduled to received only ditch water for the 2-yr growth cycle, “B” plots to receive secondary effluent for the first half of the growth cycle and ditch water thereafter, and “C” plots to have only effluent irrigation applications for the full growth cycle.
Fifty ceramic point samplers were installed in representative “A”, “B”, and “C” plots at depths of 23 to 30 cm and 46 to 53 cm (9 to 12 in. and 18 to 21 in.). which resulted in the shallower points being positioned in the tillage zone and the deeper points being positioned approximately 15 cm (6 in.) below the tillage zone. Thus leachate collected by the shallower points represented liquid available to the sugarcane root zones whereas, leachate collected from the deeper points is assumed to be generally unavailable to the sugarcane and potentially may percolate to the groundwater table. Two 1.52-m (5 ft) deep field lysimeters were also installed in a furrow row adjacent to the test plot. The sugarcane growing on one lysimeter was irrigated with ditch water while sugarcane on the other lysimeter received secondary effluent. Sugarcane parameters were monitored periodically throughout the culture cycle.
Field No. 246 was harvested in March 1975 and the associated laboratory analysis of the yields was completed and evaluated in April 1975.

The Mililani STP secondary treated and chlorinated domestic and municipal sewage effluents containing insignificant amounts of toxic chemicals represent a generally usable irrigation supply for sugarcane and grasslands in central Oahu.
Application of sewage effluent for the first year of a 2-yr cane crop cycle increased the sugar yield by about 6% compared with the control plots. However, when sewage effluent was applied for the entire 2-yr crop cycle, sugar yield was reduced by about 6% and the cane quality by about 16% even though the total cane yield increased by about 11%.
There was no apparent evidence of significant surface clogging of the soil or of soil chemical properties impairment resulting from sewage effluent irrigation during the first full 2-yr sugarcane crop cycle. Under a no moisture stress condition, a 1-mgd supply is sufficient to irrigate 61 to 81 ha (150 to 200 acres) of sugarcane by the furrow method.
The quality of percolate from the effluent-irrigated sugarcane-cultured soil was of acceptable concentration from the standpoint of groundwater quality protection: the only possible concern was for nitrogen which sporadically exceeded the 10 mg/l limit for drinking water during the first 6 to 7 months of cane growth. However, similar exceedance occurred in the ditch water-irrigated sugarcane plots and the plots irrigated with effluent during the first year and with ditch water during the second year. Furthermore, there was no major difference in the total quantity of nitrogen produced in the percolate among the three different treatments. Phosphorus, potassium, suspended solids, biochemical oxygen demand, total organic carbon, and boron were removed effectively from the applied effluent by means of irrigation; however, chloride in the percolate was essentially unaffected except for a transient increase during fertilization. Both total dissolved solids and chloride in the percolates met drinking water standards.
Human enteric viruses have been shown to be present in the majority of effluent samples examined and hence, can be assumed to be present in the effluent applied to the irrigated field. However, the absence of these viruses in all sugarcane and grass percolates sampled over a 2-yr period, plus other project virus studies conducted, suggest strongly that the possibility of contaminating deep underground water sources is extremely remote.
Survival of poliovirus was minimal in an open field area which was exposed to direct sunlight, high temperature, and dessication. In contrast, the viability of the virus was maintained for up to two months in a field of mature sugarcane where the virus was protected from the physical elements.

Bermudagrass, with periodic cutting and harvesting, proved to be an excellent utilizer of sewage effluent applied nitrogen and, thus, excelled sugarcane from the standpoint of groundwater protection. Essentially no nitrogen was recovered from the percolate at the 1.52-m (5 ft) depth below the grassed surface, whereas nearly 25% of the total nitrogen applied from chemical fertilizers and sewage effluent was recovered at the same depth in sugarcane percolate. Up to 40.47 ha (100 acres) of grassland may be irrigated with 1 mil gal/day of effluent under a no moisture stress condition. However, it has been demonstrated that fallow or bare soil appears incapable of removing significant amounts of nitrogen from the applied effluent.

Disinfected sewage effluent, similar in composition to that used in the Mililani study, may be used for irrigation of sugarcane in the first year followed by irrigation with surface water in the second year, however, when used for the entire 2-yr crop cycle without added treatment, poorer sugar yield will result.
Establishing a virus monitoring and quality control program for the treated sewage effluent before application is an essential part of an irrigation recycling program. Furthermore, development of more effective methods of virus inactivation prior to recycling is highly recommended. Precautionary sanitation measures for field workers should be practiced.
Further research on the use of effluent for irrigation sugarcane would be desirable, specifically:
1. Repeat test plot studies for a ratoon crop cycle to confirm the yield and to assess Long-term effects on the soil
2. Test with various dilutions of sewage effluent and with chemical ripeners to improve the yield
3. Investigate plugging of drip orifices in irrigation tubings in anticipation of extensive future use.


Technical Report No. 93
QUALITY AND QUANTITY OF NONPOINT POLLUTION SOURCES IN RURAL SURFACE WATER RUNOFF ON OAHU, HAWAII

Spencer K. Yim and
Gordon L. Dugan
June 1975

ABSTRACT
The quality and quantity of rural runoff was the subject of a field study conducted on the island of Oahu. The study investigated surface water runoff from three rural land uses: an undeveloped forested area, a sugarcane field, and a pineapple field.
A 37.85 l, (10-gal) tipping bucket sampler was used to collect composited runoff samples at each site and to record the volume of runoff associated with each sample.
The results of this study show that storm water runoff from undeveloped areas is the major contributor of nutrients, COD, and sediment, into wet weather streamflow. Furthermore, it establishes that nutrients and COD in this type of runoff are primarily in sediment-associated forms.
The sugarcane field samples included storm runoff and irrigation tailwater. The sample results indicate that cane field runoff in central Kunia was lower in most water quality parameters than the forest runoff in Manoa.
Insufficient samples due to dry weather prohibited a thorough analysis of pineapple field runoff.


Technical Report No. 92
NUMERICAL ANALYSIS OF ONE-DIMENSIONAL WATER INFILTRATION

Edmond D.H. Cheng
June 1975

ABSTRACT
In attempting to numerically solve the nonlinear moisture flow equation, the Galerkin process, which bears a great similarity to direct methods of the calculus of variations, and the Continuous System Modeling Program (CSMP) approach have been employed. In the finite element formulation of the governing equation, systems of nonlinear algebraic equations were developed on the basis of Linear two-dimensional triangular elements. These nonlinear algebraic equations were solved simultaneously, at each time step, by a programmed Logic of iterations. In the CSMP approach, Boltzmann’s function application and Layered soils formulation were demonstrated in obtaining horizontal and vertical moisture profiles.
The second and third degrees of polynomial interpretations of moisture diffusivity, D(6), and hydraulic conductivity, K(O), of the media were conducted. However, it was established that the former representation had only very limited applicability (as far as some Hawaiian soils are concerned)., because a second degree polynomial can accurately describe the D(O) and K(O) functions only of the wetter portion of the D(O) and K(O) vs. moisture content, 0, curves. The finite element, CSMP, and finite difference solutions were investigated and compared for Wahiawa soils with lateral moisture movement. Vertical moisture profiles for the Molokai soils and Tantalus silty clay loams were also investigated by means of the finite element method and the CSMP approach, respectively.


Technical Report No. 91
AN EXPLORATORY APPLICATION OF TWO METHODS OF ANALYZING WATER USE TIME SERIES

James E.T. Moncur
June 1975

ABSTRACT
This paper investigates the usefulness of two procedures for analyzing water use time series data. A simple procedure for translating price data into a form suitable for a standard regression estimation of the demand function for water is first noted. Then a simple spectral density estimation model is applied to Honolulu water consumption data in search of identifying periodicities or cyclical regularities of water demand. Both procedures show promise of useful interpretation, though the conclusions are tentative in keeping with the scope of this project and the limited data available.


Technical Report No. 90
AN ANALYSIS OF FOUR SHOWERS WITH RAINFALL RATES > 250 mm/hr

Charles M. Fullerton
S. Kerry Wilson
UHMET 75-03
June 1975

ABSTRACT
A computer monitored network of rapid-response Raymond-Wilson rainfall intensity gauges is operating at the Cloud Physics Observatory (CPO), on the windward coast of the island of Hawaii, recording the passage of both warm and cold cloud rain showers. During a one-year (1 July 1973 to 30 June 1974) monitoring period, 57 rainfall events were recorded with intensities > 95 mm/hr. Four of these events exhibited rainfall rates > 250 mm/hr. Each of these events is analyzed as a case study documenting the network rainfall intensity records, the associated local variations in potential gradient, surface wind velocity and atmospheric pressure, rawinsonde soundings of temperature, dew point and winds, satellite and 250-mb wind data, and an isohyetal presentation of the accumulated rainfall over the island.
Of the four cases studied, three were clearly of cold cloud origin, two being synoptic-scale events associated with low pressure centers west of Hawaii and the third a highly localized thunderstorm related to an upper level trough. The most interesting case was a 268 mm/hr rainfall intensity event almost certainly of warm cloud origin. This case (22 June 1974) may represent a record high rainfall rate from clouds known to lie entirely beneath the freezing level.
Finally, a comparison is made of the winds aloft with a calculated disturbance velocity indicating, in most cases, that the surface wind gust occurring just before the onset of rainfall is approximately equal to the wind vector at cloud level. Two anomalous cases are discussed briefly.


Technical Report No. 89
EUTROPHICATION AND FISH TOXICITY POTENTIALS IN A MULTIPLE-USE SUBTROPICAL RESERVOIR

Project Principal Investigator: Reginald H.F. Young
Co-Investigators: Gordon L. Dugan, L. Stephen Lau, Hiroshi Yamauchi
July 1975

ABSTRACT
A coordinated research effort was undertaken to investigate the intact of secondary-treated effluents from the Wahiawa and Whitmore sewage Treatment Plants on the Wahiawa Reservoir and to evaluate alternatives to the present mode of effluent disposal. The research for the Department of public Works, City and County of Honolulu, consisted of studies of the historical and institutional background of the reservoir, water and sediment quality, algae growth potential, fish toxicity of the secondary effluent, reservoir and waste water management alter-natives.
Evaluation of the water quality data indicates a high level of nitrogen and phosphorus in the Wahiawa Reservoir waters as compared to upstream control points, such as the Ku Tree Reservoir. Sediment quality indicates a definite eutrophic condition downstream of the treatment plant discharges.
Algal growth studies show that nitrogen may be the limiting growth factor for near-surface waters and phosphorus for deeper waters downstream of the treatment plant discharges and that phosphorus may be limiting upstream from those points. As expected, highest growth potential occurred with the sewage effluent or at the points of its discharge into the reservoir. The fish bioassays resulted in a 96-hr TLm at about 0.24 to 0.47 mg/l combined chlorine residues in continuous from studies for tilapia, 0.28 mg/l, for mosquito fish, and 0.05 mg/l for mollies.
A number of management alternatives were evaluated and the most feasible of these alternatives appears to be secondary effluent reuse for sugarcane irrigation or tertiary waste water treatment. Although these warrant further detailed evaluation, both as to system design, costs and institutional constraints, preliminary estimates of costs and benefits derived favor the tertiary treatment alternative.
The recommendation for management of the Wahiawa and Whitmore Village Sewage Treatment Plant effluents is the application of tertiary treatment, particularly for phosphorus removal. This level of treatment should only be necessary during the low from period of the year, and the dilution and assimilation capacity of the reservoir waters can be utilized at higher reservoir water levels with the present second level of treatment. It is emphasized that the decision to implement tertiary treatment should not be a unilateral one, but should be made in consultation with all agencies involved in management and control of use of the reservoir waters so that the final management scheme is in the best interests of all.


Technical Report No. 88
BIBLIOGRAPHY OF WATER RESOURCES OF THE HAWAIIAN ISLANDS

Rose T. Pfund, James W Wickes
May 1975

ABSTRACT
Information available on water resources of the Hawaiian Islands for the five-year period between 1967 and 1971.


Technical Report No. 87
GROUNDWATER POLLUTION FROM SANITARY LANDFILL LEACHATE, OAHU, HAWAII

Michael J. Chun, Reginald H.F. Young, Arthur S. Kawatachi, Paul R. Bolduc
April 1975

ABSTRACT
A two-year study was conducted to determine the chemical characteristics of leachate derived from domestic refuse typical of that found for Honolulu, Hawaii, and to determine the removal characteristics of select Oahu soils with respect to the substances found in these leachates. Based on these findings, guidelines for sanitary landfill site selection, in relation to the prevention of groundwater pollution, were developed.
Four Oxisol soils (Molokai, Wahiawa, Helemano, and Lahaina), one Mollisol soil (Mamala), and one Marsh soil, were subjected to both saturated and unsaturated flow conditions, using as the percolating liquid, leachate produced by saturating (domestic refuse) with water. The domestic refuse had a composition typical for that of Honolulu, Hawaii. Leachate and percolate samples were analyzed for various chemical constituents including pH, hardness, alkalinity, nutrients, chemical oxygen demand, particulate, and a number of metallic cations and heavy metals.
Ion exchange was responsible for altering the concentration of inorganic substance in the percolating liquid, while microbial degradation appeared to be the primary mechanism for removing organic substances. Under the test conditions” and using the leachate produced from typical Honolulu refuse, the soils examined were found to have relatively low exchange capacities, while at the same time, organic removals were not significant. Thus, migration of inorganic and organic substances to the groundwater table is possible, and these results suggest that a cautious approach to landfill site selection should be taken, soil depth to water table and dilution characteristics of the underlying groundwater must also be considered.
A procedure for evaluating the feasibility of landfill operations in relation to possible groundwater contamination has been suggested. This procedure utilizes the removal characteristics for the various soils as observed in this study.


Technical Report No. 86
RESPONSE TO TIDES OF COASTAL AQUIFERS: ANALOG SIMULATION VS. FIELD OBSERVATION

John A. Williams, Ta-Chiang Liu
June 1975

ABSTRACT
This report presents a summary of the work to date on the response to tides of coastal aquifers. In particular, it presents the results of experiments performed to study the influence of an oscillating water table on storativity (i.e., effective porosity), the application of both harmonic and spectral analyses to water surface time histories measured in the field near Ewa Beach and in Honolulu Harbor, and an electric analog model designed to simulate the shallow, coral-limestone aquifer at Ewa Beach, Oahu, Hawaii. Results indicate that the effective porosity for an oscillating water table will, in general, depend on the frequency of the oscillation with dependence being strong or weak as either or both the specific yield and the transitivity are larger or smaller, respectively. Also, water surface time histories can be considered to be composed of a fundamental (diurnal) component and a second harmonic (semidiurnal) component and a 24-hr record analyzed and that the resulting average values of the altitude and phase angles be used. The spectral analysis confirms that the semidiurnal power suffers a greater attenuation than the diurnal power.
It is concluded that the technique of determining aquifer properties from tidal response data is a valid one, but that the results will be less reliable than those ascertained from pump test data. The optimum results are considered to be those based on both tidal data and pump test data, as one method serves as a check on the other.


Technical Report No. 85
METHODOLOGICAL APPROACHES IN HAWAIIAN FOG RESEARCH

James H. McKnight, James 0. Juvik
March 1975

ABSTRACT
Recent studies have demonstrated the important moisture contribution from fog precipitation in mountain areas on the island of Hawaii. The present study investigates research methodologies useful in the study of Hawaiian upslope fog, including: (1) development of an improved fog gage; (2) development of indirect approximation methods for estimating average droplet sizes during precipitation episodes and separating fog and rainfall components; (3) establishment of an extensive fog sampling network on the island of Hawaii employing continuous recording equipment, for both rain, fog, and wind; (4) development of an original computer program for detailed temporal and spatial analysis of rain, fog, and wind parameters.


Technical Report No. 84
AN ECONOMIC ANALYSIS OF THE PATTERNS AND TRENDS OF WATER CONSUMPTION WITHIN THE SERVICE AREAS OF THE HONOLULU BOARD OF WATER SUPPLY

Ho-Sung Oh, Hiroshi Yamauchi
December 1974

ABSTRACT
The objectives of this study are to construct and analyze the patterns and trends of water demand in the service areas of the Honolulu Board of Water Supply, and to identify factors affecting water demand with the intent of deriving useful policy implications as well as improving on urban water demand research. To accomplish the objectives, a thorough review of the literature was conducted and some suggestions for methodological improvement were developed. Classical univariate time series analysis, data disaggregation methods, and trend analysis were used to construct the patterns and trends of water consumption. Significant variables, which affect increasing per capita water consumption, were identified through a logical sequence of data processing and reasoning. The results were confirmed by the methods of sample survey and regression analyses. Most of the data used in this study were compiled from water consumption records obtained from the Board of Water Supply.

During the period of 1960-1971, the average daily per capita water consumption increased by about 27 percent from 139 gal to 177 gal. When per capita consumption was estimated by nine service areas per capita consumption figures depicted not only a wide dispersion in absolute value but also revealed different rates of growth. The seasonal patterns of water consumption were examined on a monthly basis. There is a steadily widening seasonal fluctuation in water use over time with summer consumption increasing faster than that for winter use. The trend of sprinkling demand was estimated from maximum and minimum day water consumption’s trend equations. There is a difference in per capita consumption’s between single and multiple family dwellings, which is attributable mainly to outdoor sprinkling by households occupying single family dwellings.

The water consumption’s level in established residential areas has remained essentially constant over time. The overall increase in per capita consumption results from water use for other than indoor domestic purposes. Water consumption’s has been expanding most noticeably where there is significant construction activity. Per capita water consumption’s data were fitted by linear regression to value of construction completed and annual changes in rainfall. The equation explained 96 percent of the total variation of per capita consumption’s and the two independent variables were statistically significant. There is no evidence that residential water users have been responsive to price changes in the past. Large industrial water users appear to respond to price increase but commercial users do not. Existence of price responsiveness in industrial demand seems to have a close relationship with alternative water supply sources and nonexistence of price responsiveness in commercial demand may be associated with an incidence structure of water bill payments, which also has an important meaning in measuring the price elasticity of residential demand.
The demand approach for projection of water use is advocated by most urban water studies. Major implications of this study are that: (1) the requirement approach is still a practical means of forecasting future water need., (2) there are serious institutional limitations in the use of price as a means to promote conservation but peak load pricing may be an effective way of reducing the inequitable distribution of water supply costs, and (3) the complex economic forces that have been operating through the existing institutional framework call for some form of unified management of groundwater resource for the purpose of conservation.


Technical Report No. 83
DYNAMIC PROGRAMMING OPTIMIZATION: A WATER DISTRIBUTION SYSTEM DESIGN

Tung Liang, Kwang-Ping Yang, I-Pai Wu
HAES Journal Series No. 1871
September 1974

ABSTRACT
A computation technique based on the dynamic programming approach using the interactive Fortran language has been developed. The computerized design procedure can be used to obtain optimal design for single source water or other compressed fluid systems with a finite number of diverging branches and loops. Pumping effect on a single source system cannot be optimized, however, the developed procedure does allow quick evaluation of many alternate pumping pressures. Similarly, multiple source network with converging branches can only be evaluated by the repeated use of the computerized procedure.
Dynamic programming has been proved to be very powerful for the analysis and design of a water network. From an engineer’s point of view, this approach can be used to design any conceptual water network with little limitation.


Technical Report No. 82
FATE OF HEAVY METALS IN THE SEWAGE TREATMENT PROCESS

Myron M. Nomura, Reginald H.F. Young
September 1974

ABSTRACT
Heavy metals have long been known to exert toxic effects upon plants and animals at all trophic levels. Through the use of water as a cleansing and transporting agent, various types and forms of metals find their way into the sewerage system.
To determine the fate of heavy metals sewage treatment processes, a study covering a period of five months was conducted at the Wahiawa Sewage Treatment Plant. The study involved determining the distribution of metals in the various fractions of the waste water and sludges in addition to the overall removed in the system.
The step-aeration activated sludge treatment process, employed at Wahiawa removed most of the heavy metals, Al, Cd, Cu, Fe, Hg, Pb, and Zn, that were detected at the plant in concentrations ranging from a few parts per billion of mercury to a few parts per million of iron. Hexavalent chromium was removed somewhat less efficiently and nickel was reduced in concentration only slightly compared to the other metals monitored.
Results of this investigation showed that most of these metals were removed by precipitation with the sludges in primary treatment and further removal occurred through biological uptake in the secondary phase of treatment. The residual concentration of metals in the final effluent discharge were usually below toxic levels, with the exception of nickel, for freshwater aquatic organisms and plants.


Technical Report No. 81
A DYNAMIC WATER AND RELATED LAND RESOURCE PLANNING MODEL: ITS APPLICATION TO AN HAWAIIAN SMALL WATER SYSTEM

Tung Liang, Wen-Yuan Huang, I-Pai Wu
July 1974

ABSTRACT
Planning an optimal system of activities for generating economic goods and services within an existing natural resource capacity is a difficult problem to solve. A mathematical programming model with the capacity to check multiple resource demand and supply compatibility over many time periods was developed as a solution to this type of problem. The characteristics of natural resource supply and the demand of activities were utilized to reduce the number of time periods and to minimize the loss of the dynamic reality of the problem. Reduction in the number of time periods extended the capability of the model in solving complex resource planning problems without oversimplification,
The advance in computer memory size and speed has made multi-period mathematical programming models a practical and desirable tool in planning optimal production scheduling and optimal allocation of resources. However, the construction of a large constraint matrix generated by multi-period models remains an obstacle to the use of multi-period linear programming (LP) models. A matrix generator capable of dividing time span according to resource characteristics and IBM-MPS output compatible matrix for LP optimization was developed.


Technical Report No. 80
DETERMINING POROSITY WITH NEUTRON LOGS FROM HAWAIIAN BASALTIC AQUIFERS

Frarik I. Peterson, Man Mohan Sehgal
August 1974

ABSTRACT
Neutron count data for calibration purposes were collected by neutron logging in 4 boreholes, and porosity data were determined from photologs run on the same 4 boreholes. A neutron count-porosity calibration curve was constructed and was found to take the form of the logarithm of neutron count versus porosity. The calibration curve was calculated by linear regression analysis, utilizing empirical field data. The calibration curve is valid within the expressed 95 percent confidence intervals only for neutron logs from (1) basaltic formations, (2) uncased holes, and (3) borehole diameters from 20.32 to 30.48 cm (8 to 12 in.).


Technical Report No. 79
WATER RECYCLING OF SEWAGE EFFLUENT BY IRRIGATION: A FIELD STUDY ON OAHU

Second Progress Report for July 1972 to July 1973
Project Principal Investigator
L. Stephen Lau
Co-Investigators
Paul C. Ekern Soil and Irrigation Studies
Philip C.S. Loh Virology Studies
Reginald H.F. Young Water Quality Analysis
Nathan C. Burbank,Jr. Public Health Aspects
Gordon L. Dugan Data Management and Report Preparation
November 1974

ABSTRACT
An investigation of recycling sewage effluent by irrigation under Hawaiian conditions is being conducted in pilot field studies near Mililani Town in central Oahu under the sponsorship of the Board of Water Supply and the Division of Sewers, City and County of Honolulu. The primary objective of the project is to determine the feasibility of waste water application to the soil and its probable effects on the quality of groundwater in terms of dissolved materials and viruses. Corollary objectives are to ascertain its effects on sugarcane yield and grasslands.

The studies began in September 1971 with the construction of a five-foot (1.52 m) deep hydraulic lysimeter in a grassed area on the grounds of the Mililani Sewage Treatment Plant. The upper surface of the lysimeter was at ground level. Soil within the lysimeter was repacked to the approximate original density. In an adjacent site, a number of two-foot square pans were placed at various depths down to five ft (1.52 m) in undisturbed soil adjacent to an access pit. The lysimeter and pan areas were sprinkler-irrigated with secondary sewage effluent from the Mililani Sewage Treatment Plant on a regular schedule. Five furrows of maturing sugarcane in the nearby Oahu Sugar Company (OSC) sugarcane Field No. 240 were also irrigated with the secondary effluent while the adjoining furrows continued to receive regular irrigation water. Numerous point water samplers were positioned in both furrows and ridges of the sugarcane field at depths to 33 in. (84 cm). Thirty test plots with uniform areas of approximately 0.1 acre (0.041 ha) each were established in a newly planted (February 1973) OSC sugarcane Field No. 246. The test plots were divided into three basic irrigation schemes of ten plots each–A, B, and C. Plots “A” will receive ditch water only for the nearly 24 month culture cycle; “B” plots are scheduled to receive secondary effluent for the first half of the growth cycle and ditch water thereafter; and “C” plots will receive effluent only for the full growth cycle. Fifty ceramic plant samplers were installed in representative “A”, “B”, and “C” plots at depths of 9 to 12 in. (23 to 30 cm) and 18 to 21 in. (46 to 53 cm). Two five-foot (1.52 m) deep field lysimeters were also installed in a furrow row adjacent to the test plot. The sugarcane growing on one lysimeter is irrigated with ditch water while the other receives secondary effluent. Sugarcane growth parameters are being monitored periodically throughout the culture cycle. The soil within the test sites of both the grass and sugarcane areas is of the Oxisol Lahaina series, the , general soils type on which approximately 90 percent of Hawaii’s irrigated sugarcane is grown.

Raw sewage, secondary effluent, and leachate from the soils were assayed for various physical, chemical, sanitary, and microbiological quality parameters. Analyses for pesticides and heavy metals were also performed occasionally. A virus laboratory, the first of its kind in Hawaii, was established at the University of Hawaii at the initiation of the project to serve the project and to assist in training the personnel of the Board of Water Supply. Consumptive use of water was determined by use of the hydraulic lysimeter.


Technical Report No. 78
SOME CHARACTERISTICS OF HAWAIIAN HIGH INTENSITY RAINFALL

Charles M. Fullerton, S. K. Wilson
UHMET 74-01
August 1974

ABSTRACT
A computer monitored network of rapid response Raymond-Wilson rainfall intensity gauges has been established at the Cloud Physics Observatory (CPO), on the windward coast of the island of Hawaii, to record the passage of both warm and cold showers. These showers are characterized by high intensity rainfall (50 to 300 mm/hr) and an associated increase in atmospheric pressure, a change in wind velocity, and a reversal of the electric potential gradient. The showers often occur at night, during the maximum of the diurnal pressure oscillation, and frequently in groups of two to four with an interval of 10 3 to 10 4 seconds between separate showers. A relationship between the height of the base of the trade wind inversion and the total amount of rainfall was observed, indicating that almost no rainfall occurs if the inversion base is less than 2 km.

A drop-size instrument (DSI) was developed and used to measure the raindrop-size spectrum. From this measurement and the rainfall intensity, an estimation of the liquid water content (LWC) of precipitating clouds was derived. The LWC (2.0 to 8.0 g/m3) was found to be larger than that generally assumed for trade wind showers.


Technical Report No. 77
THE QUALITY OF COASTAL WATERS: SECOND ANNUAL PROGRESS REPORT

Sea Grant College Program, Year 05
Project Principal Investigator
L. STEPHEN LAU
Sea Grant Cooperative Report UNIHI-SEAGRANT-CR-74-05
September 1973

ABSTRACT
This report summarizes the results of the second year of investigative and evaluative work of the University of Hawaii’s Sea Grant Program project, “Quality of Coastal Waters” The general objectives of this multidisciplinary project are to identify, develop, and evaluate the critical physical, biological, and rational parameters needed in formulating effective policies, institutions, and systems for protecting the quality of coastal waters in Hawaii. To this end, the attainment of eight specific objectives is assigned to faculty specialists participating in the 14 activities which comprise the Project. These specialists also assist the Principal Investigator in planning the work and in interpreting the results.
Research activities for the project year consisted principally of field and laboratory studies of coastal waters initiated in the first project year but with increased emphasis on biota and sediment. Assistance was rendered to the State Department of Health in the revision and updating of the State Water Quality Standards.

Kahana Bay was selected for study as a coastal water area under the influence of relatively undeveloped land. Land contribution of nutrients to the bay via Kahana Stream and all nonpoint routes was found to be small despite the perennial nature of the surface and subsurface discharges. However, the nitrogen and phosphorus levels measured for Kahana Bay waters and in the contiguous open ocean water exceeded the levels allowed under its state Class AA water classification. Coliform organism concentrations met the Class A rather than Class AA standards. Thus, the Kahana Bay water quality tends to satisfy the Class A standard rather than the Class AA standard.

Heavy metals, especially lead, copper, zinc, chromium, and nickel, appeared consistently and within a range of a few to a few hundred ppm in the bay sediments, stream sediments, and watershed soils. The ubiquitous nature of their presence is related to the parent rocks from which the soils and sediment are derived. However, mercury and cadmium were only occasionally detected in the sediments and when detected, occurred at only within a range of a fraction of to a few parts per million. DDT was detected in the range of a few parts per trillion in the Kahana Bay sediment together with only periodically detected and very low levels of dieldrin, DDE, a and y chlordane. In the Kahana Bay water both heavy metals and DDT were detected but only at levels similar to open ocean water, i.e., a fraction of, or a few parts per billion for the heavy metals, and only a few parts per trillion for DDT.
The project’s approach to revealing the effects of urban land development is selection of single predominant type of urbanization of land to reveal the cause-effect relation.

Recreational use of coastal land and water in and domestic urban use of water and the abutting land in Hawaii Kai Marina and east Maunalua Bay furnish such situations. Domestic sewage is collected and removed from the areas.

Investigative results for the Hawaii Kai area and Maunalua Bay showed a general trend to improvement in water quality from the marina to the near-ocean bay waters. Nitrogen levels in the bay and only the near-ocean station were within the Class A state standard by which the water bodies are classified but phosphorus levels exceeded the standard elsewhere. All heavy metals were consistently present in the coastal sediments in the parts per million level. The levels of the ubiquitous pesticides analyzed, DDT, dieldrin, and PCP, (the latter is used primarily for termite control in house construction), were at least one order of magnitude higher than in the Kahana Bay sediments, thus reflecting intensive urban activities associated with a relatively new and growing residential development.

In the Hawaii Kai Marina and coastal waters, heavy metals were detected in the usual minimal parts per billion level as in open ocean water, and DDT, dieldrin and PCP were in the usual parts per trillion range. A turbid water plume in Maunalua Bay was occasionally identified and apparently was related to currents and roiling bottom sediments rather than any liquid discharge. A biota study of the bay waters was completed and detailed.

Coastal water quality data obtained for the Mamala Bay waters off in support of a conjunctive study by Chave for the Corps of Engineers and coliform monitoring by the Department of Health are reported. in general the data satisfied state requirements for Class A waters except for phosphorus. Coral abundance was generally less toward Diamond Head than toward Ala Wai Canal. which is the only major drainage canal intercepting the surface runoff from the valleys and discharging into coastal waters. From the findings, there is little evidence which would attribute any specific water quality effect solely to the presence of intense recreational activity at Sandy Beach represents a rather complex situation and departs from the project approach: the open ocean coast beach being popular, the land use changing from rural and undeveloped to residential urban development, and above all, the coastal water receiving treated domestic effluent. Shoreline water quality data were obtained to complement the studies undertaken by the consulting firm of Sunn, Low, Tom, and Hara, and the routine monitoring by the State Health Department. Results for the project area showed clear shoreline water similar to but with higher nutrients than Kahana Bay water and the state Class A standard Levels. However, the study by the consulting firm of the offshore condition adjacent to the Hawaii Kai sewer outfall showed that there is little significant effect to the coastal water and benthos from the discharge of treated wastewater off Sandy Beach.

A baseline survey of benthic biota, particularly coral and micromollusc abundance and diversity, and fish was performed for Kailua Bay, the proposed Mokapu outfall site, and the existing Kailua sewer outfall. While the greatest abundance and species diversity of the fish were not near the outfall, the highest standing crop of micromolluscs is near the outfall. The occurrence of micromolluscs is comparable with the patterns in other areas of similar depth and substrate.

Nonpoint discharge studies of sugarcane production and milling wastes were continued but at a reduced scale on Kauai. Observations of mill waste discharge and coastal water, sediments, and biota were made both before and after the 90-year old Kilauea Sugar Company closed down its operations in north Kauai in 1971. Untreated mill wastes were found to be the major contributing factor to the presence of coliforms, sediments, trash, and bagasse. The effect was largely an extensive visible plume in the coastal waters and debris in both the water and on the beach. Sediments, rather than water, harbored most of the nutrients, heavy metals, and pesticides in the ocean. DDT, although not used by the sugarcane industry, was present in small amounts in all wastes and sediments. Herbicides used in sugarcane culture did not appear in coastal waters. A striking aesthetic improvement of the coastal water and the beach quickly followed the cessation of mill waste discharge. Coastal water qualities continued to improve: phosphorus decreased to better than Class AA standards, DDT and PCP were detectable only at parts per trillion level. The rapid improvement is attributed to both the cessation of mill waste discharge and the heavy sea. Beach and ocean sediments continue to harbor about the same level of heavy metals but contain a much decreased amount of nutrients. Fish have reappeared rapidly since 1973. No apparent changes in micromolluscs have been observed since the cessation of mill operation. Tentative conclusions of the continued Kilauea investigative studies are: no evidence of eutrophication in coastal water, adverse effects of discharge mostly transitory, and epibenthic communities more influenced by waves, currents, and coastal topography than by mill waste discharge.

Studies were continued in south Kauai to assess the effect of changed operation practices by the McBryde Sugar Company subsequent to an EPA survey of coastal waters of the area in 1968. Company practices demonstrate that it is possibze to operate milzing operations without discharge to the ocean, and to prevent irrigation tailwater overflows except flooding due to intense rainfall. At the time of reporting, the coastal waters of Wahiawa Bay showed an anomalously high nitrogen content while no pesticide residues were found in the offshore water except for the one to two parts per trillion DDT which seems to be present everywhere.

Evaluative summaries were detailed for several key quality parameters in water and sediment. Heavy metals were ubiquitous and in parts per million range in coastal sediment in Hawaii. This suggests that if standards for the level of heavy metals in dredge spoil were to be set, care should be taken not to fix unrealistic levels that cannot possibly be attained. In the coastal waters, heavy metals also occur but only in the parts per billion range, a level quite comparable to the level in ocean water. Conjunctive studies of mercury uptake in an aquatic food chain from the water and sediment were continued and detailed.

Of the insecticides, the presence of DDT in sediments is ubiquitous. In Maunalua Bay and Hawaii Kai sediments, dieldrin, and a and y chlordane are found frequently and with highest concentration in the Low parts per billion range. Their occurrence may be attributed to prior and current continous use of these chemicals in the abutting land area and the poor sediment circulation within the Hawaii Kai Marina. In coastal waters insecticides were generally undetectable or at only a few parts per trillion. PCP, like DDT, seems to occur ubiquitously.

Herbicide residues in West Loch of Pearl Harbor and Kaiaka Bay were studied. Atrazine and ametryne do not appear to be a problem, however, because of its persistence in soils, diuron can be found in coastal sediments because eroded agricultural soils are transported with storm runoff.

Kahana Bay water contains about the lowest amounts of nutrients in coastal waters. The state standards for nitrogen and phosphorus were exceeded in all areas except for Kilauea, in the case of nitrogen, and McBryde, in the case of phosphorus.

The use of mircomolluscs as an indicator organism was reported with a differentiation noted in species between coastal areas affected primarily by silting compared to areas affected primarily by nutrient input. In the former situation Bittium zebrum becomes the major fauna component and standing crops and diversity values are conspicuously depressed. In the latter case, the community changes towards dominance by suspension feeding forms which depend on primary productivity of the water columns. Also associated strongly with silted reef flats is Obtortio pupoides. The responses of an ecosystem to land-generated effects are changes in structure from a grazing herbivore environment with associated frondose algae to either a rubble associated ecosystem with few species or to a eutrophic state with many suspension feeders and Low diversity.

The principal changes in institutional arrangements noted in the project year are those resulting from the passage of the Federal Water Pollution Control Act Amendments PL 92-500. The effects of this legislation will be far-reaching and result in changes which include: new discharge permit requirements, reporting of operating and monitoring results for wastewater treatment facilities, a minimum requirement level of secondary treatment for municipal wastewaters, and industrial waste treatment effluent guidelines. The full impact of these and other changes is not yet apparent although some delays have incurred in regulatory actions and attempts to implement legislation.


Technical Report No. 76
A STUDY OF THE EFFECTS OF SECONDARY EFFLUENT ON WAIMANO AND WAIAWA STREAMS

Stephen S. Aoyama, Reginald H.F. Young
May 1974

ABSTRACT
A field study was made between September 1972 to May 1973 to assess the water quality changes in Waiawa and Waimano Streams, particularly the effect of chlorinated effluent from the Pacific Palisades Sewage Treatment Plant on the receiving stream waters. Some changes were very apparent, especially those of an aesthetic nature, the visible change in the color and turbidity of the water and the sulfurous odor of septic sewage. These obvious changes were indications of changes in water quality which could only be determined in the laboratory by chemical analysis.
The actual degree of change in stream quality and amount of recovery cannot be determined until Palisades treatment plant ceases operation, and sewage effluent is no longer discharged into the stream.
Waiawa Stream is an intermittent stream with a large drainage area. The developed areas within the Waiawa basin represent 20-25 percent of the total drainage area, but the sewage flow from one such developed area, Pacific Palisades, is the source of perennial flow for the lower section of Waiawa Stream. However, even with the large drainage area and intermittent streamflow, self-purification takes place in the short distance from the point of sewage effluent discharge to Pearl Harbor.


Technical Report No. 75
NEUTRON WELL LOGGING IN HAWAII

Frank L. Peterson
February 1974

ABSTRACT
In 1970, the Water Resources Research Center initiated a study of neutron well logging techniques in Hawaii. The primary objective of this study was to apply neutron logging techniques to the problem of obtaining reliable porosity data and relating these to water yields from Hawaiian aquifers.

Neutron well logging in Hawaiian basaltic formations has produced much important qualitative and quantitative information. The most important application has been the determination of porosity in the saturated zones. Interpretation of neutron log responses in Hawaiian basaltic formations is similar to conventional neutron log interpretation in sedimentary formations. Neutron count varies as an inverse function of porosity. High neutron counts are indicative of low porosities and low neutron counts are indicative of high porosities. In general, the neutron logs are extremely responsive to detailed changes in formation porosity, and of particular importance is that the reproducibility of neutron logs from the same well is excellent. Neutron logs from Hawaiian wells also are extremely responsive to the saturated-unsaturated boundary and to the casing termination. Surprisingly, the neutron logs show little consistent response to nominal hole diameter or borehole fluid salinity.

Probably the best use of the neutron logs is in conjunction with other borehole geophysical logs. Correlation between neutron Logs and electric resistivity logs is particularly good.


Technical Report No. 74
A PRELIMINARY REPORT ON URBAN HYDROLOGY AND URBAN WATER RESOURCES: OAHU, HAWAII

Yu-Si Fok
October 1973

ABSTRACT
The major tasks under Phase II of the project were to: (1) adapt and evaluate several existing watershed simulation models for their applicability under local conditions, (2) expand the data collection effort in the research watersheds, and (3) identify problem areas for subsequent study.

The instantaneous unit hydrograph (IUH) theory was explored in detail. The results indicate that the successive routing method developed by Nash (1957) has better applicability on urban watersheds near Honolulu. The parameter, N, representing the conceptual number of reservoirs, decreases as urbanization progresses.

In the adaptation of the Kentucky Watershed Model (KWM), it was found that the basic logic of continuous balancing of the water budget within a given watershed is applicable to Hawaiian conditions. The development of KWM to meet Hawaiian requirements would entail two to three more years as has been the experience in Kentucky. A preliminary computer program has been established and simulated daisy streamflow from Kalihi watershed obtained.
In the Road Research Laboratory Model (RRL) adaptation, there was poor correlation between the rainfall and runoff data collected from the St. Louis Heights research watershed. This may be attributable to deficiencies in instrumentation as well as inexperience in data colIection, as the data used for simulation were obtained during early stages of the study.

In the multiple regression method for determining peak flow, the statistical method appeared to establish a reasonable empirical relationship between peak flow and urbanized area of a given watershed, as well as between time to peak and urbanized area. However, additional data are required to fully establish such a relationship.
Of the mathematical models tested for rainfall-runoff relationship, the nonlinear time variant method gave the best peak discharge simulation. Also Nash’s IUH model (1957) gave good simulation.

All watershed simulation models tested indicated that more hydrological data are prerequisite to the development of a reliable urban hydrology simulation model for Oahu. The data collection program has been expanded to include evaporation, soil moisture, wind speed, solar radiation, and water quality in addition to rainfall and streamflow records gathered since initiation of the project. .


Technical Report No. 73
APPLICATION OF REVERSE OSMOSIS TECHNOLOGY TO HAWAIIAN LOW QUALITY WATERS

Bei-Jiann Chang, Reginald H. F. Young, James C. S. Chou
November 1973

ABSTRACT
A study of the application of reverse oamosis technology to the treatment of Hawaiian low quality waters was conducted. The purpose of the study was to investigate the technical and economical feasibility of utilizing reverse osmosis technology to renovate waste waters after varying degrees of conventional treatment, and to desalt Hawaiian brackish groundwater from both basaltic and reef limestone aquifers.

The experimental investigation of the technical feasibility of renovating waste water and desalting brackish groundwater was conducted with a small reverse osmosis pilot unit at four test sites on the island of Oahu. The operation of the reverse osmosis pilot unit in processing waste waters suffered from the problem of performance decline. However, the pilot unit’s operation with brackish groundwater yielded promising results. In general, high rejections of total dissolved solids, refractory organics, nutrients, bacteria, and virus were accomplished by the unit.
Two waste water reclamation schemes incorporating the reverse osmosis process were considered possible in Hawaii. Treatment expenditures of the two schemes were estimated at 97.8 cents and 103.2 cents per 1000 gallons of treated waste water. Based on a cost model developed for estimating desalting costs by reverse osmosis plants with spiral wound modules, product water costs in Hawaii were estimated at 83.7 cents, 63.4 cents, and 49.7 cents per 1000 gallons for 1, 10, and 50 mgd plants, respectively.


Technical Report No. 72
SOME STATISTICAL ANALYSES OF HAWAIIAN RAINFALL

Edmond D.H. Cheng, L. Stephen Lau
August 1973

ABSTRACT
Monthly rainfall data of several stations in Kalihi Basin, Manoa Basin, and Kaneohe Area, all on Oahu, and the central sloping area of Molokai were correlated to watershed parameters of the areas. Distance measured from the station to a common station located seaward from all stations has proven to be the most important of the three parameters studied, the other two being the exposure and the elevation of the area. Both linear and nonlinear regression functions were developed.

The central tendency of the monthly rainfall for the high rainfall part of the southeastern part of the Island of Oahu was found to require approximately forty years of record to stabilize. The analysis also shows that mean converges. to a specified level generally faster than median.
The intensity-duration relation of intense rain for specified recurrence interval for the high rainfall part of the Manoa Basin portrays accurately an inverse straight-line relationship on a plot of log-log coordinates, suggesting extension of effort to other climatically widely different regions in Hawaii. The developed relation agrees well with the reported finding of a prior Weather Bureau study employing a different approach.


Technical Report No. 71
BASELINE QUALITY DATA FOR KALIHI STREAM

Gordon K. Matsushita, Reginald H.F. Young
June 1973

ABSTRACT
The purpose of this study was to determine the changes in stream water quality related to variations in land use patterns and to establish some baseline data for assessing the Hawaii State Water Quality Standards for surface waters. Effects on water quality were determined by collecting and analyzing water samples taken from four sites that were located along the course of Kalihi Stream from October 1971 to August 1972. The sites were selected within different land use areas along the stream to account for any variation in contribution from undeveloped and developed lands. Water samples were analyzed for physical, chemical, bacteriological parameters as well as pesticides and heavy metals. Rainfall for the drainage area and stream discharges were also recorded during the study period.

The stream water quality for wet and dry weather flows were found to compare favorably with other Hawaiian investigators and were in the same order of magnitude as those in the U.S. and other countries. Pollution loads were also calculated on a lbs/acre/day basis and these results compared favorably with U.S. and Hawaiian investigators. The parameter concentrations and pollutional loads were found to increase in a downstream direction as incremental and individual subbasin drainage areas increased in development, land use activity, population density and housing density. The water quality results established baseline data for Kalihi Stream and were compared with the State Water Quality Standards. It was found that fecal and total coliform densities exceeded Class 2 Standards during dry and wet weather conditions and that the nutrient standards for Class A waters were also exceeded during dry and wet weather. There was no significant pesticide contribution to pollution of Kalihi Stream as all results were in the low ppt range.


Technical Report No. 70
EVALUATION OF METHODS OF PUMPING TEST ANALYSES FOR APPLICATION TO HAWAIIAN AQUIFERS

John A. Williams and Ronald L. Soroos
July 1973

ABSTRACT
Pumping test data from eight locations including the islands of Oahu, Maui, and Molokai were selected and analyzed. The test data were selected on the basis of completeness, reliability, and aquifer type and boundary conditions involved. Analyses included the standard Theis, Thiem, and Jacobs methods as well as those techniques which deal with boundaries (Stallman method), partial penetration of the well (Hantush-Theis method), leaky aquifers (Walton method), and anisotrophy (Hantush method for anisotropic aquifers). In addition, the Zanger method for partially penetrating wells and equilibrium data was also used.

Results of the several different analyses were compared and recommendations made as to which method or combination of methods seemed best suited for Hawaii aquifers. In the case of the principal basal aquifer, the Hantush-Theis method for non-equilibrium data or the Zanger method for equilibrium data are recommended. In the event that leakage or boundaries are a factor, the former method used with early-time data is recommended.


Technical Report No. 69
THREE-DIMENSIONAL ZONE MODEL LOG INTERPRETATION

Louis J. Shamey, William M. Adams
September 1973

ABSTRACT
To facilitate the interpretation of geophysical electrical well logging data, the apparent resistivity has been calculated in a model in which the experimental situation is approximated by three coaxial cylindrical zones containing the drilling mud, flushed rock, and surrounding rock matrix, respectively. This three-zone model is shown to yield results that differ by as much as 25 percent from the earlier two-zone model calculations.

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