Flood control at km 130 Padaleunyi Toll

Flood is one of the natural phenomena that often brings loss of property and life. Mostly, it occurs during a high-intensity rainfall event in the catchment area which results in high river flow that cannot be accommodated by river cross sections. In Bandung area, one of the locations that are often hit by the flood is located on km 130 of the Padaleunyi toll road. This flood occurred due to the overflow of the Cilember and/or Cimancong rivers tributary which flows parallel to the toll road, inundating the toll road segment with low elevation at around km 130+500. This paper aims to analyze the effective flood control methods in the above location. With catchment area around 2.3km2, which is relatively small, peak flood discharge calculation was carried out using a rational method. Hydraulics simulation was carried out using HecRas, based on river field measurement data of Cilember and Cimancong river cross-section. Analysis result shows that the combination between flood embankment construction and river normalization provides a significant decrease in flood water level in km 130 Padaleunyi toll road. The reinforced concrete vertical wall was considered as the appropriate flood protections structure due to the limited space available between the river and the toll road segment. This paper also underlined the impact of the increasing loss of water retention areas on an increased risk of flooding.