Rainfall time-distribution analysis for flood design computation case study upper Cikapundung River Basin

Abstract

Flood discharge computation plays an important role in predicting flood occurrence in certain areas, especially areas which have relatively heavy storm events throughout the years, such as upper Cikapundung watershed. The analysis process requires data input of storm design which have its hourly distribution. The rainfall time-distribution can be obtained if there’s an hourly rainfall recording station. Problems occur when no hourly rainfall data is available; therefore the storm design can’t be distributed hourly. But, as an alternative, the rainfall time-distribution can use the ones that have been developed in other areas. To obtain the alternative rainfall time-distribution, the mass curve and outflow hydrograph result in upper Cikapundung watershed model is compared between the one using rainfall time-distribution from real-time data (in this case from Station Bandung) and the one using other rainfall time-distributions. Rainfall time-distribution for Bandung has an 8-hour duration which is selected based on the most often occurrence of rainfall throughout the years. The calibrated model results in similar mass curve and outflow hydrograph by using SCS type III rainfall time-distribution with 8-hour duration as well. This time-distribution therefore can be applied as an alternative to represent rainfall hourly distribution for upper Cikapundung watershed.