Demand-based optimal fuzzified hedging rules associated with variation of standardized streamflow index and storage

Abstract

Due to the uneven spatial and temporal distribution of rainfall and the rapid streamflows in southern Taiwan floods and droughts occur frequently Therefore improving the water supply efficiency of reservoirs is one of the important issues for water resources management The rule curves divide the storage of the reservoir into several zones with clear boundaries to indicate the state of the reservoir Besides the rule curves are lowered in flooding season due to flood prevention If the inflow during the wet season is not as expected the stored water may not guarantee sufficient water supply for the coming dry season which indicate the traditional rule curves cannot represent the water supply capability of the reservoir This study chooses the Nanhua reservoir which located in southern Taiwan as an example to demonstrate the proposed methodology This study formulates a demand-base rule curves and applies fuzzy theory to fuzzify the storage zones Furthermore this study considers the standardized streamflow index (SSI) and storage tendency of the reservoir with different time scales to construct water releasing rules The optimal hedging rules are derived with five shortage indices for multi-criteria optimization The results show that different time scale of the SSI and the storage tendency have different effects on reservoir operations However the three-month time scale is the best scenario among the models

Date of Award	2019
Original language	English
Supervisor	Jenq-Tzong Shiau (Supervisor)