CONTRIBUTION OF BASEFLOW AND SOIL MOISTURE TO DISCHARGE IN A WATERSHED WITH SEMI-ANNUAL RAINFALL (CASE STUDY: CIKAPUNDUNG SUB-WATERSHED)

• Main Author: Yusran Rizqullah, Alecio
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/82683
• Institution: Institut Teknologi Bandung

Cikapundung river is one of tributaries of Citarum River which plays a role as the main water source for the residents in Bandung Basin area. Despite it’s role as the main water source, Cikapundung River also often act as the main cause of flooding in southern region of Bandung. This shows needs to understand the characteristics of the Cikapundung River. This research will identify the hydrometeorological characteristics, focusing on the role of baseflow and discharge response to rainfall in the Cikapundung Sub-watershed, which is suspected to exhibit semi-annual rainfall patterns. This research used various data including rainfall, total runoff, elevation, land use, and soil type. The GSSHA model is used to simulate soil moisture scenarios, represent baseflow. Before conducting simulate GSSHA model, the model is calibrated by comparing the simulation runoff with observation runoff. This process continues until the surface roughness and infiltration input parameters produce a simulation runoff that matches the observation runoff. This research reveals that annual runoff pattern of Cikapundung Sub-watershed resemble its rainfall pattern. However, peak runoff experiences a month lag time for each peak. This may be influenced by rainfall infiltrared in upstream during the first peak, resulting in a higher runoff recorded downstream during the scond peak. Additionally, the GSSHA modelling indicates that the Cikapundung Sub-watershed has a tendency for high level of soil moisture.