Term Project Outline

CE 394K Surface Water Hydrology
University of Texas at Austin

Analysis of Groundwater Recharge in an Arid System

by Jean-Philippe Nicot

In the 1980's, the federal governement decided that each state has to dispose of its own low-level radioactive waste. The proposed site for the state of Texas is located in West Texas along I-10 in the vicinity of Sierra Blanca in Hudspeth county. The site was chosen in part because it sits in an area with low precipitation. In such an arid climate, most of the infiltrating water quickly evaporates back to the atmosphere. This minmizes the risk of pollution to the groundwater in case of a leak from the disposal site.


Because the recharge rate to the groundwater, if any, is expected to be low, I decided not to try to determine how long it takes for the infiltrating water to reach the watertable and how much actually does it. What I intend to do is to compute what precipitation event is needed for the water pulse to reach the watertable and how frequent that precipitation event is in the present climatic conditions. In other words, I would do a time series analysis of the precipitation coupled with a sensitivity analysis (intensity and duration of a precipitation event, seasonal variations, soil type) in the unsaturated zone.

Information Sources

The data I can use are: - precipitation data - evaporation model - unsaturated flow model: SUTRA fromUSGS, UNSAT1 from the USDA Salinity laboratory or any other program which may be more convenient. - hydrogeologic studies (from the BEG and Dr Charbeneau)

Expected Results

It is anticipated that the precipitation event needed to recharge the groundwater is vey unlikely and also that it will take a larger event in the summer than in the winter because of the larger evapotranspiration.
The same approach may be applied on any site and if time allows will be done on different climatic regions.
Limitations: I assume there is no preferential flow (which is likely to be wrong) and no retardation (conservative value for contaminant transport).

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