Modeling bengawan solo river to predict the area inundation of flood

Bengawan Solo River is the longest river in Java Island. The river have length is approximately 600 km and 16.100 km² in area of watershed. Bengawan Solo watershed is divided into three zones that are Upper Solo River, Middle Solo River, and Lower Solo River. In this case, The Middle Solo River is represented by Kali Madiun Catchment Area. Bengawan Solo River is often flooded. A flood is an unusually high stage in a river. Discharge exceed than full bank capacity can be flood in the river. The damages caused by floods are loss of life, property and economic due to disruption of economic activity. There are many solutions to minimize of effect of flood. In this study make a model of Bengawan Solo River to analysis of Hydraulics River. The results of hydraulics analysis are used to create map of flood inundation. The map of flood inundation is used as information for peoples who stay in Bengawan Solo Watershed as warning of flood. If information could be known early then it can help people to be careful and minimize of damages. Model of Bengawan Solo River is produced from hydraulic analysis of HEC-RAS. HEC-RAS process is using flow hydrograph from hydrological analysis. HEC-HMS is software is used to hydrological analysis in Bengawan Solo Watershed. Input data needed to process of HEC-HMS is average of rainfall data, return periods of rainfall at 2 years, 5 years, 10 years, and 25 years. The area rainfall is determined by Polygon Thiessen methods. The return periods of rainfall data is determinable using Gumbel's method. The last result of this process is discharge data, elevation of surface water, and prediction of flood inundation. In this study produced a map of flood inundation. This map is referring of flood and non-inundation area at Bengawan Solo Watershed. It is a benefit to minimize of flood damages.