WELL CATCHMENTS AND TIME-OF-TRAVEL ZONES IN AQUIFERS WITH RECHARGE

The classical analytical method used to map catchments and time-of-travel zones of pumping wells was originally derived for another purpose and takes no account of recharge (Bear and Jacobs, 1965). Generalized catchment shapes are presented here for aquifers with recharge. They can be scaled to field situations through two or three nondimensional parameters. A semianalytical path line tracing model was used to generate the shapes. It contains new expressions for pore water velocities in two infinite strip, recharged aquifers, one with two fixed head boundaries, the other with one impermeable boundary. The resulting catchments differ significantly in both shape and size from catchments estimated by the no-recharge method. Generalized results are also presented for time-of-travel zones which are noticeably smaller than those calculated by the no-recharge method. Comparison with an equivalent recently released model from the U.S. Environmental Protection Agency shows the latter to give poor estimates of catchments and time-of-travel zones.