Dam break analysis of Situ Gintung Dam collapse reconstruction

Abstract

On March, 27th 2009 Situ Gintung dam collapsed. Situ Gintung dam failure has been analyzed based on the condition of watershed, reservoir, and embankment on March, 27 2009. Hydrological analysis and slope stability analysis are combined to analyze the major causes gintung collapse. Watershed analysis using ARC-GIS software, routing in reservoir using HEC-HMS model, and stability condition was strudied using Geo-Slope. Input data, parameters, and model assumptions are very important to get the right results. Hydrological analysis results show that rain occurred on March 26, 2009 with a rainfall intensity of 111 mm/day was only classified as rainfall with a return period of 5 years. Reservoir routing show that water level elevation on March, 27 2009 was only 70 cm above the spillway crest or 1,3 m below the embankment crest with a peak flow of 36,2 m3/s, so it didn't cause overtopping on the embankment. Slope stability analysis results show that the factor of safety of 1,19 < 1,5 (standard), it show that there was the weakening of the dam, such as scouring, erosion, and cracks. It can be concluded that the main factor of the collapsed was caused by scouring and cracks.