Introduction

WATER QUALITY OF NORMAL AND STORM-INDUCED SURFACE WATER RUNOFF: KANE’OHE BAY WATERSHED, OAHU, HAWAII FEBRUARY 1974 TO MARCH 1975

WATER QUALITY OF NORMAL AND STORM-INDUCED SURFACE WATER RUNOFF: KANE’OHE BAY WATERSHED, OAHU, HAWAII FEBRUARY 1974 TO MARCH 1975

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.