Effect of changes of streamflow regimen on reservoir yield

Abstract

A presumptive approach was used to gain insight into the question: How do alterations of streamflow characteristics affect downstream objectives? The special case of flows changed in timing and volume from management on the tributary watershed in tandem combination with a downstream reservoir was considered. Change in mean yield of the reservoir was taken as an index of utility of the streamflow changes. Uniform increases of streamflow of 5% and 15% and a half month delay in the annual hydrograph were assumed either singly or in combination, storage yield computations made, and differences in yields determined. Not all extra streamflow was found to be useful although the increases gained utility with increasing storage availability. A timing delay was most important with smaller storage availability and then only to a limited degree. Flow increases combined with a timing delay produced results that were approximately simple additions to the two individual effects.