Numerical Analysis in Dengkeng River Using Nays2DFlood

摘要

Flooding is one of the disasters that occur in almost all regions of Indonesia every year. The National Disaster Management Agency of Indonesia (BNPB) recorded 1,999 flood disasters since the beginning of 2018 until October 2018 causing 4,157 people dying and disappearing. Dengkeng River is a tributary of the Bengawan Solo River that experiences flooding problems when the rainy season arrives. Previous studies have produced one-dimensional river (1D) which does not provide detailed information of flooding modelling and analyzed sedimentation rates from secondary data. However, there is rare research and detailed observation on this subject in this area. Therefore, flood simulation models are required to identify flood-prone areas. In this study, a two-dimensional (2D) river model using the International River Interface Cooperative (iRIC) Nays2DFlood software from Japan has been used to observe flood-prone areas around the Dengkeng River and field observation was done in prone areas. The results showed that the Cawas sub-district tends to have the highest flooding potential due to the overflow of the Dengkeng River. On the other hand, the result of field observation showed sediments that settled in Tukuman Weir are dominated by coarse sand and gravel that tend to be influenced by the upstream in Merapi Volcano. Moreover, flood damage continues to occur as the consequences of riverbank erosion and high sedimentation at specific locations on the Dengkeng River.