EFFECTS OF TOPOGRAPHY AND SOIL PROPERTIES ON RECHARGE AT TWO SITES IN AN AGRICULTURAL FIELD

摘要

Field experiments were conducted from 1992 to 1995 to estimate ground water recharge rates at two sites located within a 2.7-hectare agricultural field. The field lies in a sand plain setting in central Minnesota and is cropped continuously in field corn. The sites are located at a topographically high (upland)site and a topo- graphically low (lowland) site in an effort to quantify the effects of depression focusing of recharge. Three site-specific methods were used to estimate recharge rates: well hydrograph analysis, chlo- rofluorocarbon age dating, and an unsaturated zone water balance. All three recharge methods indicated that recharge rates at the Lowland site (annual average of all methods of 29 cm)exceeded Those at the upland site(annual average of 18 cm).