DEVELOPMENT AND APPLICATION OF AN ANALYTICAL MODEL OF STREAM AQUIFER INTERACTION/

A mathematical model to simulate stream/aquifer interactions in an unc onfined aquifer subjected to time varying river stage was developed fr om the linearized Boussinesq equation using the principle of superposi tion and the concept of semigroups. The mathematical model requires an estimate of three parameters to simulate ground-water elevations; tra nsmissivity, specific yield, and recharge. The solution has physical s ignificance and includes terms for the steady-state water level, the s teady-state water level as influenced by a change in river stage, a tr ansient redistribution of water levels in the aquifer from the previou s day, and a transient change in water level caused by a change in riv er stage. The mathematical model was tested using observed water table elevations at three locations across a 2-km-wide alluvial valley aqui fer. The average absolute deviation between observed and simulated dai ly water levels was 0.09 m. The difference in river stage over the tes t year was 4.9 m. (C) 1997 Elsevier Science B.V. (C) 1997 Elsevier Sci ence B.V.