A PARSIMONIOUS MODEL FOR SIMULATING FLOW IN A KARST AQUIFER

This paper describes the hydrologic system associated with the Barton Springs portion of the Edwards aquifer and presents a lumped parameter model capable of reproducing general historical trends for measured w ater levels and spring discharge. Recharge to the aquifer was calculat ed based on flow loss studies of the creeks crossing the recharge zone and on estimates of the rate of diffuse infiltration of rainfall. Flo w measurements on each creek above and below the recharge zone were us ed to develop a relationship between how above the recharge zone and t he rate of recharge. The five-cell groundwater model, each cell corres ponding to one of the watersheds of the five main creeks crossing the recharge zone, was developed to support the management objectives of t he City of Austin. The model differs from previous models in that the aquifer properties within cells are allowed to vary vertically. Each c ell was treated as a tank with an apparent area and the water level of a single well in each cell was used to characterize the conditions in that cell. The simple representation of the hydrologic system produce d results comparable to traditional groundwater models with fewer data requirements and calibration parameters. (C) 1997 Elsevier Science B. V.