Field Analysis on the Role of Three-Dimensional Moisture Flow in Ground-Water Recharge and Evapotranspiration

In comparison to evapotranspiration, ground-water recharge is usually a small part of the hydrological cycle in areas of low precipitation; nevertheless, the replenishment of our underground water resources depends upon this important process. A field program was developed to quantify recharge and soil-water flow directions through sandy soil in a desert landscape near Socorro, New Mexico. The instrumentation consisted of two climatological stations and a dense grid work of 160 tensiometers and 12 neutron probe access tubes to monitor pressure head and moisture content located within a 24 m2 area. The results of measurements from July 1988 to July 1989 showed that soil-water uptake by saltbush and desert shrubs did not induce significant horizontal flow components. We conclude that for this, and similar sites, a one-dimensional analysis of soil-water movement is adequate. Recharge was about 0.4 cm/yr and comprised about 2.3% of the 17.4 cm/yr rainfall.