Evaluating Flood Control Potentials of Prior Release at an Agricultural Reservoir Equipped with Spillway Gates

― A case study at the S dam ―

Abstract

In order to quantify the flood control potentials of agricultural reservoirs equipped with spillway gates, we evaluated the effects of prior release at the S dam to reduce peak discharge during floods (peak cut ratio) by applying constant-volume release operation. We found that the implementation of a constant-volume release operation could reduce peak discharge by up to 60.2% during a total rainfall event of 200 mm/d. Although the peak cut effect decreased as the total rainfall increased, it was obtained even in a heavy rainfall event of 350 mm/d. The application of a constant-volume release operation at the S dam did not have an adverse effect in the recovery of the reservoir storage level when it stored inflows at the recession stage of floods, under the condition with the total rainfall amount to initiate a prior release operation.