Dynamic rule curves for multipurpose reservoir operation for different floods

Abstract

Abstract Dynamic flood control rule curves (DFCRCs) that balance the use of conservation space between flood control and conservation purposes are usually necessary for the operation of a multipurpose reservoir. This paper therefore proposes a procedure to apply the DFCRCs of an historically-based actual flood for reservoir operation versus different floods whose hydrograph shapes vary widely. The proposal uses related-size characteristics (e.g. net retention of the DFCRCs and peak discharge of associated outflows) in a stepwise manner from those of the smallest return period to those of the largest one. Illustrative applications of the procedure to the operation of the multipurpose Ubol Ratana Dam (The Nam Pong Basin, Thailand) have indicated that it enables the DFCRCs to ensure the reservoir's operation against various floods. Its operational results for the large and moderate floods in 1990 and 1995 are comparable to those of historically based floods. In addition, impact assessment of climate change on the operational performance has shown that the system could not protect the areas upstream and downstream of the dam from the HadCM3A2 and HadCM3B2 floods at the 80th and 95th percentile levels during the future 2050s period.