The effect of flood on slope stability along downstream riverbank of MuaraBangkahulu River, Bengkulu City, Indonesia

Abstract

The flood which occurred due to the rainfall intensity in Bengkulu City of Indonesia could inundate the downstream area of MuaraBangkahulu River, especially TanjungAgung Sub-District. In 2019, a huge flood had occurred in Bengkulu City and triggered the environmental effect to riverbank in TanjungAgung. This environmental effect is a massive slope failure on downstream riverbank in TanjungAgung. This study is therefore conducted to analyze the slope stability in the area during the normal and the critical conditions. A slope stability analysis using finite element method is performed. First, the maximum discharge of MuaraBangkahulu River is estimated. Furthermore, slope stability analyses are conducted by considering the normal condition and the increase of river water level due to the maximum discharge (the critical condition). Mapping of factor of safety for riverbank slope and soil deformation is conducted. The results showed that slope along downstream riverbank of MuaraBangkahulu could undergo slope failure under both normal and critical condition. The results also showed that the factor of safety decreases due to the increase of river water level. The results of this study could be used by local government to consider slope countermeasure in the study area