EFFECTIVE RAINFALL ESTIMATION BASED ON SPATIO-TEMPORAL RAINFALL LEADS TO CIWIDEY FLASH FLOOD

• Main Author: Heryati, Nindy
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/53537
• Institution: Institut Teknologi Bandung

This research aimed to analyze the influence of spatial-temporal variation of rain on flash flood events in Ciwidey. The influence of spatial-temporal variation is done by comparing an assumed uniform rainfall hydrograph with a non-uniform rain hydrograph. The magnitude of non-uniform rainfall is obtained from estimating the value of radar rainfall, yielding a hydrograph peak discharge that adjusts the peak discharge value obtained from Nugraha (2018). In estimating peak discharge, trial-and-error method was used; changing the value of rainfall until the non-uniform rainfall peak discharge is equal to the uniform rainfall peak.Hydrographs are produced from hydrology simulation using distributed hydrologic model, GSSHA. The parameter is precipitation without infiltration and evaporation. The results showed that the flash flood that occurred in Ciwidey on May 3, 2017 was caused by moving rainfall clouds, generally concentrated in the upstream and there were two peak events, at 12:22 - 12:54 and 13:12 - 13:58 (Western Indonesian Time). The result of the influence of spatial-temporal variation on peak discharge is bigger than uniform rainfall peak discharge. Uniform rainfall peak discharge tends to underestimate peak discharge of 26%.