Techniques for computing rate and volume of stream depletion by wells

The effects on flow of a nearby stream from pumping a well can be calculated readily using dimensionless curves and tables. Computations can be made of: (1) The rate of stream depletion at any time during the pumping period or after the cessation of pumping; (2) The volume induced from the stream during any time, both during pumping or after the cessation of pumping; and (3) The effects, both in rate and volume of stream depletion, of any selected pattern of intermittent pumping. Sample computations illustrate the use of the curves and tables. An example shows that intermittent pumping may have a pattern of stream depletion not greatly different from a. pattern for steady pumping of an equal volume.

The residual effects of pumping, that is, effects after cessation of pumping, on streamflow may easily be greater than the effects during the pumping period. Adequate advance planning that includes consideration of residual effects thus is essential to effective administration of a stream-aquifer system.