ASSESSMENT OF FLOOD RISK REDUCTION IN BENGAWAN SOLO RIVER: A CASE STUDY OF SRAGEN REGENCY

Bengawan Solo experiences flooding almost every year and it has been a big problem since it causes damage and losses affecting many people in the area. Sragen is the Regency with the greatest loss due to flooding of the Bengawan Solo River which is the longest river in Java Island with 16,100 km(2) basin area. Dykes are the structural intervention usually proposed to deal with flood water. The objective of this study is to conduct an assessment of dyke height requirement in order to reduce flood risk in Sragen Regency along Bengawan Solo River. The assessment is based on risk level according to regulations of the Head of National Disaster Management Agency Number 2 in 2012, regarding the general guidelines for the assessment of disaster risk. Hazard levels are obtained from the relationship between hazard index parameters and exposed population index. Loss levels are obtained from the relationship between the hazard level parameter and the loss index. Flood risk level is determined from the level of losses and capacity. For mitigation purposes, flood risk reduction analysis has been conducted through a structural approach by simulating dyke construction around the Bengawan Solo River. Several scenarios of dyke height (2m, 4m, and 6m) have been simulated to assess flood inundation.