Water-level, springflow, and s-treamflow data were used to develop simple and multiple linear-regression equations for use in estimating water levels in wells and the flow of three major springs in the Edwards aquifer in the eastern San Antonio area. The equations provide daily, monthly, and annual estimates that compare very favorably with observed data.Analyses of geologic and hydrologic data indicate that the water discharged by the major springs is supplied primarily by regional underflow from the west and southwest and by local recharge in the infiltration area in northern Bexar, Comal, and Hays Counties.

Annual recharge data obtained from historical records and mean-annual precipitation data computed from rainfall records were used to develop simple linear-regression equations for use in estimating annual recharge for seven subbasins in the San Antonio area. Adjustments were made to the precipitation parameter to account for the effects of year-end storms. The standard errors of estimate of the regression equations ranged from 26 percent for the Blanco River basin to 45 percent for the area between the Sabinal and Medina River basins.Annual-recharge estimates computed by use of the regression equations compared favorably with estimates made on the basis of observed streamflow and precipitation data.The report includes a brief review of the geology and hydrology of the Edwards aquifer, a discussion of the preparation and evaluation of the precipitation data used in the regression analyses, and a brief summary of the method previously used to estimate recharge.

No abstract

No abstract

Cover. Block diagram of hypothetical area showing hydrology of mined and unmined areas (modified from Hobba, 1981, fig. 4.0-B).