Water Budget for the Island of Kauai, Hawaii
Water-Resources Investigations Report
95-4128
By: Patricia J. Shade
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Abstract
A geographic information system model was created to calculate a monthly water budget for the island of Kauai. Ground-water recharge is the residual component of a monthly water budget calculated using long-term average rainfall, streamflow, and pan-evaporation data, applied irrigation-water estimates, and soil characteristics. The water-budget components are defined seasonally, through the use of the monthly water budget, and spatially by aquifer-system areas, through the use of the geographic information system model.
The mean annual islandwide water-budget totals are 2,720 Mgal/d for rainfall plus irrigation; 1,157 Mgal/d for direct runoff; 911 Mgal/d for actual evapotranspiration; and 652 Mgal/d for ground-water recharge. Direct runoff is 43 percent, actual evapotranspiration is 33 percent, and ground-water recharge is 24 percent of rainfall plus irrigation. Ground-water recharge in the natural land-use areas is spatially distributed in a pattern similar to the rainfall distribution.
Distinct seasonal variations in the water-budget components are apparent from the monthly water-budget calculations. Rainfall and ground-water recharge peak during the wet winter months with highs in January of 3,698 Mgal/d (million gallons per day) and 981 Mgal/d, respectively; a slight peak in July and August relative to June and September is caused by increased orographic rainfall. Recharge is lowest in June (454 Mgal/d) and November (461 Mgal/d).
| Publication type | Report |
|---|---|
| Publication Subtype | USGS Numbered Series |
| Title | Water Budget for the Island of Kauai, Hawaii |
| Series title | Water-Resources Investigations Report |
| Series number | 95-4128 |
| DOI | 10.3133/wri954128 |
| Edition | - |
| Year Published | 1995 |
| Language | ENGLISH |
| Publisher | Geological Survey (U.S.) |
| Contributing office(s) | Pacific Islands Water Science Center |
| Description | iv, 25 p. |
| Google Analytic Metrics | Metrics page |