National Institute for Water Resources, Water Resources Research Institute Program
3/1/2013 - 2/28/2014
Reductions in the base-flow discharges of the high-level development tunnels of the Waiahole Ditch System are believed to be associated with regional recharge distribution shortfalls to the vast and heavily utilized Pearl Harbor aquifer. Such a distribution may be observed by shallow index monitor wellhead level responses located within distinct hydrologic sectors of the Pearl Harbor aquifer. The objective of this study is to define the relationship between high-level dike compartments and the down-gradient recharged Pearl Harbor basal aquifer. Field verification of presently measured flume and weir discharges of the Waiahole Ditch System development-tunnels will be conducted to assess the efficacy of these devices in providing accurate tunnel discharge accounting. The extensive compiled data will be used for future research to study the overall sustainability of the study area. In addition, base flow discharges will be evaluated by using climatological data during past episodes of drought. Univariate multiple regression models will be used to evaluate the relationship among predictor variables (rainfall distribution, tunnel base flow discharges, Pearl Harbor ground water production), and response variable (monitored wellhead levels). Semi-partial correlations will be used to identify the unique contribution of predictor variables upon a response variable. The relationship between high-level dike compartments and the down-gradient recharged Pearl Harbor basal lens will offer an insight into future adverse climate changes upon ground water sustainability as framed through a retrospective analysis of significant drought episodes. This will benefit policy makers in preparation for diminishing sustainable yields among high levels sources and the Pearl Harbor aquifer. Owing to the potable quality o water from high-level Waiahole tunnels, consideration to its utility and sustainable as a future municipal resource may also represent an option to costly ground water treatment of plantation-era fumigants found in Pearl Harbor ground water sources.