NORMALISASI SUNGAI BATANG LEMBANG UNTUK REDUKSI BANJIR SOLOK SUMATERA BARAT

Batang Lembang River is located in Solok Regency which has length of 19,90 km and watershed area ± 308 km2. Every year there is a flood in the Batang Lembang River due to the inability of the river to accommodate its flood discharge. The overflow that inundated the surrounding area was cause by the existing cross section of the river not being able to accommodate river water. Therefore, it is necessary to analyze the cross-sectional capacity of the river from upstream to downstream using the HEC-RAS 4.0 software. This study aims to determine the peak flood debit of Batang Lembang River and evaluate the cross sectional capacity of the Batang Lembang River with HEC-RAS 4.0 software. After conducting a hydrological analysis and hydraulics analysis, the appropriate flood control measures can be determined. The flood countermeasures are carried out by planning the construction of retaining walls that are overflowing after normalization. Some calculation results of this research can be concluded that the peak discharge of the Batang Lembang River in Q10 year amounted to 576.353 m3/s, and from the analysis result of the river cross-sectional capacity is obtained that twelve points is having flood. Furthermore, for the points that have flood to plan a retaining wall (parafet) with a height of 6.60 m and a width of 6.0 m. From the planned normalization process, it can reduce the water profile till 15,69% of the existing conditions