STUDY OF CIPUNAGARA RIVER FLOOD CONTROL IN SUBANG DISTRICT WEST JAVA PROVINCE

• Main Author: Ghoni Majdi, Abdul
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/64473
• Institution: Institut Teknologi Bandung

Cipunagara River have a total length ± 104 km and average of width 40 m, is the main river of the Cipunagara watershed system (1203 km2), its spring located at the foot of Tangkuban Perahu Mountain (2706 m asl) in Bandung Regency, and most of the downstream area is part of Subang District. Based on the results of previous studies and record of flood events, Cipunagara River is known to have a fairly serious flood problem. Inundation areas recorded include the Pamanukan District, Legon Kulon and the Pusakanegara District, this area consists of ± 22 km2 located on the right bank and ± 2.5 km2 on the left bank, it damaging agricultural areas and settlement areas where located on the northern part of the Panturas highway. Hydraulic modeling of Cipunagara River using by HEC - RAS 4.10 started from the upstream, ie at confluence between Cipunagara River with Cigadung River down to the downstream (estuary), along ± 29 km, gives the result that the existing capacities of the river was not able to convey design flood discharge Q25 = 1377 m3/s safely. Flood control alternative through structural measures, among other : the construction/ improvement of dikes, required dikes with average height 3.90 m (maximum) and 1.15 m (average); the river channels improvement on downstream, can reduce the flood elevation 0.89 m (maximum) and 0.35 m (average); the river channels improvement on downstream and upstream, can reduce the flood elevation 1.14 m (maximum) and 0.63 m (average); the construction of retarding basin (380 ha) can reduce the flood elevation 0.32 m (maximum) and 0.11 m (average) and shift the peak time of flood from 8 hours to 10 hours. The combination of flood control alternative by structural measures, results : the combination of river channels improvement on downstream with dikes, required dikes with maximum height = 3.47 m and average = 1.15 m; the combination of river channels improvement on downstream and upstream with dikes, required dikes with maximum height = 3.47 m and average = 1.00 m; the combination of retarding basin with dikes, required dikes with maximum height = 3.90 m and average = 1.10 m. Alternative through non structural flood control by reforestation up to 30% of Cipunagara watershed areas into the woods, reduce the flood peak discharge 8.30% in average.