Under the current (1996) conditions of planned irrigative and municipal water supply of Shihmen Reservoir, inflow discharge at the damsite, estimated flows at downstream control points (Yinshan Weir and Houtsun Weir) and other associated data, the annual shortage ratio and shortage index through reservoir operation simulation are called the basic shortage ratio and shortage index. These two numbers are the criteria to evaluate the reliability of water supply from the Reservoir. On the basis of the statistical characteristics of historical flow record, the multiplicative seasonal autoregressive integrated moving average (SARIMA) model generates 1000 sets of synthetic flow series. The corresponding annual shortage ratio and shortage index based on each synthetic flow series can be obtained through reservoir operation simulation. This information provides the reliability of reservoir’s water supply. Through reliability analysis, the probabilities of satisfying the current and the original water supplies from the Reservoir can be determined and then served as the valuable information for decision-makers to process water resources management.
