THE EFFECT OF RAINFALL TEMPORAL DISTRIBUTION ON FLOOD HYDROGRAPH, CASE STUDY CIMANUK WATERSHED

• Main Author: Mutia Abidin, Dina
• Format: Theses
• Language: Indonesia
• Subjects: Teknik sipil
• Online Access: https://digilib.itb.ac.id/gdl/view/48115
• Institution: Institut Teknologi Bandung

Garut Regency, West Java is located at The Upper Cimanuk Watershed where floods often occur. Damaged basin conditions and high rainfall in the Upper Cimanuk River are considered to be the causes of the floods. In anticipation of the flood, water structures are constructed with expected flood/runoff capacity. Due to the limitation of hydrological data needed, to plan water resources buildings, synthetic hydrographic models are uses to describe the discharges in the area. This study is conducted so the parameters used to build the hydrograph model can properly represent the condition of Cimanuk Watershed. The analysis is using SCS-CN hydrograph model with modified initial abstraction ratio (?). Percentage of rain distribution obtained from the analysis of heavy and very heavy rain events that occurs in Leuwidaun Sub Watershed. Results from the 49 events analysis are 2 formula: ?=0.0215CH+0.1532 for light rainfall (<20mm) and ?=0.0131CH-0.1805 for moderate and heavy rainfall (?20mm). HSS SCS-CN with original value ? = 0.2 gives 99% average deviation of peak discharge (Qp), and HSS with modified ? gives 26% average Qp deviation.