Scientific Investigations Report 2005-5146
U.S. GEOLOGICAL SURVEY
Scientific Investigations Report 2005-5146
Prepared in cooperation with the
County of Kauai Department of Water
By Scot K. Izuka, Delwyn S. Oki, and Chien-Hwa Chen
Recent declines in water levels and productivity in some wells and tunnels in the Lihue Basin, Kauai, Hawaii, have raised concerns about the future reliability of ground-water sources. The trend of declining water levels coincides not only with increases in ground-water development, but also with decreases in applied irrigation and periods of lower-than-average rainfall. Water-balance computations indicate that the sugarcane industry had, at its peak, artificially increased recharge by about 25 percent over natural conditions. Periods of decreased precipitation and irrigation, concurrent with declines in observed ground-water-levels, caused substantial reductions in ground-water recharge relative to periods of normal rainfall and full irrigation. Simulations of recent decreases in irrigation, a recent drought, and hypothetical future scenarios of droughts and irrigation cessation indicated basin-wide recharge decreases of 7 to 83 percent relative to the condition of normal rainfall and full irrigation.
For the period during the observed decline in ground-water levels, the water-balance simulations indicate that the effect of the recent drought was greater than the effect of reduced irrigation. Effects of droughts, however, are temporary conditions that will eventually be mitigated by wet periods, whereas loss of irrigation in the Lihue Basin may be permanent and have a greater long-term effect. Effects of irrigation also may appear to be small relative to basin-wide recharge, but the effects of irrigation changes are concentrated in former irrigated sugarcane fields, and many wells with recent declining water levels are near these former sugarcane fields.
Abstract
Introduction
Description of Lihue Basin
Changes in Ground-Water Recharge
Summary and Conclusions
References Cited
Appendix A
This report is available online in Portable Document Format (PDF). If you do not have the Adobe Acrobat PDF Reader, it is available for free download from Adobe Systems Incorporated.
Download the report (PDF, 5 MB)
Document Accessibility: Adobe Systems Incorporated has information about PDFs and the visually impaired. This information provides tools to help make PDF files accessible. These tools convert Adobe PDF documents into HTML or ASCII text, which then can be read by a number of common screen-reading programs that synthesize text as audible speech. In addition, an accessible version of Acrobat Reader 5.0 for Windows (English only), which contains support for screen readers, is available. These tools and the accessible reader may be obtained free from Adobe at Adobe Access.
| AccessibilityFOIAPrivacyPolicies and Notices | |
  |
|
