EVALUATION OF SURFACE-WATER - GROUND-WATER INTERACTION COEFFICIENTS IN WATER-RESOURCES PLANNING MODEL.

A water-resources planning model formulated as a mixed-integer program is used to screen and sequence proposed projects such that the present cost of meeting future water demands is minimized. Surface-water - ground-water interactions are represented in the model by a set of constraints guaranteeing minimum surface-water flow which can be affected by diversions and well-field pumping. When well fields in a planning region are hydraulically connected to streams, consideration must be given to the impact of ground-water pumping on surface-water flows. The streamflow-requirement constraint in the planning model contains surface-water - ground-water interaction coefficients, which relate the quantity of water withdrawn from the stream to the quantity of water pumped by the well fields.