Predicting pumping water levels in single and multiple wells using regional groundwater models

Abstract

Models of regional groundwater flow do not accurately predict pumping water levels in wells. Previous workers have shown that, under several restrictive assumptions, the predicted level is valid for a very large well with a radius of approximately 0.2a, where a is the finite difference mesh spacing. This result is shown here to be valid for time variant conditions, and for aquifers receiving recharge. Methods of adjusting for water table and partially penetrating conditions are derived. Regional models place wells at nodes and so they only approximate to the distance between wells, and between wells and boundaries. Corrections for these approximations are derived. The various adjustments to calculate pumping water levels in wells from regional model predictions are combined into an “operations” model to study a part of the Lima aquifer where there are 23 wells in 12 km 2. The performance of most wells is adequately reproduced.