Development of Probability Based Rule Curves for a Reservoir

Abstract

The probability based rule curves were developed for Mun Bon and Lam Chae reservoirs, Nakhon Ratchasima province, using 50 synthetic generated monthly inflow sequences of 48 years each. There were 4 levels of risk including 0.05, 0.10, 0.20 and 0.30 for each of the upper and the lower rule curves. Mun Bon reservoir used the actual water use for developing the probability based rule curves. Since Lam Chae reservoir was the newly constructed reservoir, only some part of the project was irrigated. Three water use scenarios were used for developing the probability based rule curves.Those were 100%, 75% and 50% of upland crop area. The probability based rule curves of Mun Bon and Lam Chae reservoirs were used in reservoir operation simulation using the proposed reservoir operating rules and the 48 years of monthly historical data, 1952-1999. The standard operating policy was also used in Mun Bon and Lam Chae reservoir operation simulation using the same set of data in order to see the effectiveness of the developed probability based rule curves. The simulation result showed that the failure indices in terms of the number of months, sum and sum squared of water shortage of the probability based rule curves were smaller than those of the standard operating policy.