Sensitivity analysis of streambed leakance downstream of Caballo Reservoir

Derrick OHara, University of Texas at El Paso


Modeling transient effects of streams near well fields is an important tool for understanding water balance within the Rio Grande Project (Project). The results are known as stream leakage. Stream leakage quantifies the amount of water seeping from a stream, canal and/or drain to/from a well field. Stream leakages near the Canutillo Well field, primary river losses for years 2005 through 2010 along with historical gain/losses and allocations of surface water with the associated agreements were evaluated. ^ The overall loss rates per mile in the Project for years 2005 to 2010 averaged -0.75 cubic feet per second (cfs). The historical river loss study displayed greater depletions in the Mesilla Valley. This was conducted by reviewing volume releases from storage and available diversions downstream of Caballo Reservoir to the El Paso Gauging Station, located approximately 104 river miles south of Caballo Reservoir. Surface water allocation and associated agreements were also explored. These allotments provided insight on the surface water system in the Rincon and Mesilla Valleys. The total water allocated and the connection between shallow wells in the Valleys had been previously studied. The evaluation of historical gain/loss rates and total yearly allocation produced a correlation, R 2 =.7863. Further evaluation of return flows will define the correlation. ^ The methods applied to groundwater modeling have been extensively used to estimate the amount of stream leakage occurring in the Rio Grande Basin. A sensitivity analysis was performed on the conductance factor in the Weeden and Maddock groundwater MODFLOW. These analysis determined the factor to demonstrate variability, from one percent to 125 percent, the associated uncertainty was evidence in all related wellfield pumping scenerios.^

Subject Area

Agriculture, General|Water Resource Management

Recommended Citation

OHara, Derrick, "Sensitivity analysis of streambed leakance downstream of Caballo Reservoir" (2012). ETD Collection for University of Texas, El Paso. AAI1518205.