The Safety of Bengawan Solo River Embankment at Dengkeng-Pusur Segment in The Return Periods of Discharge

Abstract

This study aims to assess the safety of the Bengawan Solo River embankment at Dengkeng-Pusur segment in the return periods of discharge in terms of the freeboard’s adequacy. The embankment was designed to control flood discharge of 1.240 m3/sec with a freeboard of 1.1 meters. The hydraulic analysis using Hec-Ras software from point P.1 to P.14 with a Q2 return period of discharge of 811.9 m3/sec to a Q100 return period of discharge of 1442.5 m3/sec shows that the embankment is still able to pass the flood discharge. However, based on the freeboard’s adequacy, at a Q10 return period of discharge of 1050.1 m3/sec, the freeboard on the left embankment at P.8 less than 1 meter, namely 0.98 meters. Thus, it can be concluded that the Bengawan Solo River embankment at the Dengkeng-Pusur segment is not safe starting in a Q10 return period of discharge because, at any time, the capacity of flow discharge can be exceeded by wave phenomena and backwater effects so that can be endanger the embankment. This analysis also shows that the embankment is not safe at the design flood of discharge.