Flash flood assessment at Upper Cisadane Watershed using land use/land cover and morphometric factors

The regions of upstream Cisadane watershed tend to gain more flash flood cases and reduce the water catchment due to encroachment of settlement areas. Researches on flash flood disaster and land use/land cover change are important to reduce the impact of flash flood disaster to the community and environment. This study aims to: 1). Determine morphometric characteristics and land use/land cover changes and 2). Prioritize sub-watersheds for flash flood disaster management. Land Use Land Cover (LULC) and morphometry parameters were used to prioritize the sub-watersheds as a basis for flash flood disaster mitigation in the research sites. The land use data from three different periods (2011, 2015, and 2020) were modelled to understand the land use change in the research sites. Morphometric characteristics were quantitatively analysed over three aspects including linear, relief, and shape aspects over seven sub-watersheds. Morphometric parameter was considered as an important parameter in order to understand the capacity and hydrology condition at a particular watershed towards precipitation rate. According to the land use change analysis gained from 2011 to 2020, the trend of land use change was dominated by settlement area and cultivated land. These areas tend to grow in 2015 and 2020. The integration results of LULC 2020 and morphometric analysis revealed that the Sub Basin 1 (SB 1) sub-watershed was the top most priority for flash flood mitigation planning, followed by SB 7, SB 3, SB 5, SB 4, SB 2, and SB 6.