Study of evaporation and recharge in desert soil using environmental tracers, New Mexico, USA |
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| Authors: | A-R Shurbaji A R Campbell |
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| Institution: | (1) Hydrologic Science, Veihmeyer Hall, University of California, Davis, CA 95616-8628, USA, US;(2) Department of Earth and Environmental Sciences, New Mexico Tech., Socorro, NM 87801, USA, MX |
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| Abstract: | The purpose of this study is to investigate the rates and mechanisms of recharge and evaporation in soils of a desert environment
using two environmental tracers (chloride and oxygen-18). The profiles of chloride concentration and oxygen-18 enrichment
in soil-water, together with the depth distribution of water content in soil, reveal information about long-term recharge
and instantaneous evaporation processes without needing to know the physical properties of the soil. Three holes were hand-augured,
in different desert settings in southeastern New Mexico. The chloride concentration profiles were used, with the chloride
mass balance method, to estimate long-term recharge rates in these three holes as 0.5, 0.8, and 2.4 mm yr–1. Analysis using a bimodal flow and transport model shows that possibly 85% of the recharge occurs via movement of water through
preferred pathways in the root zone. Preferential flow was evident in all three sampling sites. Clay layers have a noticeable
effect on the development of water content distribution and thus on oxygen-18 enrichment and chloride concentration profiles.
The spatial variation in clay layering partly explains the variation in recharge rate estimates.
Received: 13 October 1995 · Accepted: 15 November 1995 |
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| Keywords: | Recharge Evaporation Oxygen-18 Chloride Environmental tracers |
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