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.
Objectives
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).
My mailing address is:
jpnicot@mail.utexas.edu
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