Vadose-zone techniques for estimating groundwater recharge in arid and semiarid regions
- CSIRO, Glen Osmond, SA (Australia)
- Pacific Northwest Lab., Richland, WA (United States)
- Desert Research Inst., Reno, NV (United States)
Both physical and chemical methods have been used to estimate recharge in arid and semiarid areas. Our review indicates that indirect, physical approaches, such as water balance and Darcy flux measurements, are the least successful, while methods using tracers (e.g., Cl, [sup 3]H, and [sup 34]Cl) have been the most successful in estimating groundwater recharge in dry regions. Lysimeters, which can directly measure root-zone drainage, have been useful in quantifying recharge, particularly for coarse soils, but are costly to construct and operate. Of the tracer techniques available, Cl balance techniques appear to be the simplest, least expensive, and most universal for recharge estimation. In Australian studies, under native vegetation in semiarid areas, Cl profiles were found to be remarkably uniform, indicating very low and relatively uniform rates of groundwater recharge. Following changes in land use, recharge appeared to become much more variable, increasing more than two orders of magnitude. Methods for scaling point estimates of recharge to large areas using indirect techniques (such as nondestructive electromagnetic induction) have also been developed. In deep unsaturated zones, the pressure response in the soil water may be recorded in the profile, and simple field measurements may be used to obtain semi-independent verification of recharge rates determined by using Cl balance techniques. 75 refs., 4 figs.
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 7113326
- Journal Information:
- Soil Science Society of America Journal; (United States), Journal Name: Soil Science Society of America Journal; (United States) Vol. 58:1; ISSN 0361-5995; ISSN SSSJD4
- Country of Publication:
- United States
- Language:
- English
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540211* -- Environment
Terrestrial-- Basic Studies-- Radiometric Techniques-- (1990-)
540311 -- Environment
Aquatic-- Basic Studies-- Radiometric Techniques-- (1990-)
99 GENERAL AND MISCELLANEOUS
990200 -- Mathematics & Computers
ARID LANDS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
CHLORINE
CHLORINE 36
CHLORINE ISOTOPES
DEUTERIUM
ELECTRON CAPTURE RADIOISOTOPES
ELEMENTS
EVEN-EVEN NUCLEI
GROUND WATER
HALOGENS
HYDROGEN COMPOUNDS
HYDROGEN ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
LYSIMETERS
MATHEMATICAL MODELS
MEASURING INSTRUMENTS
NITRATES
NITROGEN COMPOUNDS
NONMETALS
NUCLEI
ODD-EVEN NUCLEI
ODD-ODD NUCLEI
OXYGEN 18
OXYGEN COMPOUNDS
OXYGEN ISOTOPES
RADIOISOTOPES
RECHARGE
SOILS
STABLE ISOTOPES
TRACER TECHNIQUES
TRITIUM
WATER
YEARS LIVING RADIOISOTOPES