In this study, a general computer simulation model of the hydrologic system has been applied to three particular problems in a specific geographic area. The three phases into which the study was divided are as follows: (A) The effects on ground water table elevations of a barrier to prevent surface runoff from the northern highlands from entering the study area; (B) The effects on the groundwater table elevations of varying the densities of native phreatophytes; and (C) An examination of the accumulation, locations and relative amounts of surface runoff.