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Title: ESTIMATING GROUND-WATER RECHARGE AND UNCERTAINTIES USING 10-MINUTE SOIL WATER CONTENT AND PIEZOMETRIC HEAD MEASUREMENTS

Author
item Timlin, Dennis
item Starr, James
item CADY, RALPH - U.S.N.R.C.
item NICHOLSON, THOMAS - U.S.N.R.C.

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 7/28/2004
Publication Date: 11/2/2004
Citation: Timlin, D.J., Starr, J.L., Cady, R., Nicholson, T. 2004. Estimating ground-water recharge and uncertainties using 10-minute soil water content and piezometric head measurements [abstract]. ASA-CSSA-SSSA-CSSS Annual Meeting. CD-ROM.

Interpretive Summary:

Technical Abstract: Water balance approaches to quantifying hydrological cycles are popular because the data requirements are often minimal and the methods are simple. Most water balance studies use daily or monthly data to quantify the components of the water budget. The simple methods include bucket models to estimate infiltration, redistribution and evapotranspiration of water. Recent advances in technology have produced methods to automatically measure soil water contents [multi-sensor capacitance probes (MCP)] and piezometric head at high temporal frequency. Measurements of soil water content at the minute scale provides the ability to obtain near real-time measurements of water content to observe soil water dynamics. The objective of this study was to investigate analysis methods for a data set having water contents and piezometric head measured at 10 minute intervals and many locations. Ground-water recharge estimates were compared to those from less frequent measurements of water content. Time series analysis can be used to obtain information on soil water fluxes, evapotranspiration and ground-water recharge from these data. The results show that use of water content measurements can provide reliable estimates of ground-water recharge. Because water content measurements cannot provide good estimates of fluxes when the soil water content is high, they may underestimate ground-water recharge. Evapotranspiration is a critical co-value to measure or estimate.