Operation plan of the Wonogiri Reservoir, Central Java, Indonesia

Abstract

The feasibility study estimated that the Wonogiri Reservoir will be able to supply water with a 90 percent reliability. This estimation was supplied by frequency analysis. Twenty years of monthly streamflow data of the Solo River were used in these calculations. The current study estimates a 5.82 percent probability of failures, which is provided by water balance calculations. The streamflow data are extended by the first-order autoregressive (Markov) model. The generated streamflows are multiplied by a runoff factor. The feasibility study specified that a flood having 4,000 cms peak with the March-1966 flood standard hydrograph can be effectively reduced to 400 cms by the reservoir, where the water level will reach an elevation of 137.7 meters. The current study researches the reservoir's flood control ability by reservoir routing. Assuming the water level reaching 138.2 meters the reservoir can reduce a flood of 4,400 cms peak.