Numerical Modeling and Analysis of Ground Water and Surface Water Interaction in a Desert Environment

A small watershed at the edge of a large desert valley was modeled for the quantity of flow available to sustain surface water flows to wetlands and to allow for water supply for nearby residences.  Ten groundwater wells were instrumented across the lower portion of the watershed for real time collection of water level information around a wetland near a fault zone.  A barometric and temperature weather station was established in the lower watershed to provide correlative data.  Continuous 5-minute interval data were collected for two months during the late summer months.  Modeling and analysis of the data was done using a variety of methods to establish the natural yield of the groundwater system to the wetlands.  Rainfall events were captured in the data along with aquifer testing to analyze the interaction of the fault system with groundwater baseflow.  Diurnal changes in groundwater elevation across the verdant wetland on the edge of the desert were found to be correlative with daily temperature highs.  The area wide loss of groundwater from water table fall was compared to the modeled consumptive use estimates using the Blaney-Criddle method in a model for crop consumptive use.  Good agreement was found in the two methods.  Further modeling of groundwater base flow in the watershed using aquifer parameters derived for the watershed from on-site testing was compared to consumptive use.  These were also found to be in good agreement.  A strategy for groundwater utilization for water supply is being developed to meet growing population needs along with strategies to sustain wetland habitat.