SURFACE RUNOFF ANALYSIS USING SWAT (SOIL AND WATER ASSESSMENT TOOL) IN SILENG SUBWATERSHED, PROGO WATERSHED, CENTRAL JAVA

• Main Author: Amalia Sholichah, Putri
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/69011
• Institution: Institut Teknologi Bandung

Surface runoff is a hydrological condition that plays a role in landslide disasters in Indonesia, one of which is in Borobudur District. Therefore, it is important to quantify surface runoff, by reviewing the watershed as part of the hydrological cycle. The Borobudur District is dominated by the Sileng subwatershed as a part of Progo watershed, in which there is a watershed rehabilitation area by PT Adaro Indonesia. This area is important to analyze in order to provide information supporting the program. In this research, SWAT (Soil and Water Assessment Tool) is used as a quantification model for surface runoff at the watershed/subwatershed scale, which needed to be calibrated and validated. This study aims to simulate, calibrate, and validate the SWAT model on the Progo watershed with Duwet Station as the outlet, perform SWAT simulations on the Sileng subwatershed scale with calibrated parameters, also estimate surface runoff in the Sileng subwatershed and the area of watershed rehabilitation by PT Adaro Indonesia. SWAT calibration at Progo watershed scale resulted in good performance (NSE 0.67 and RSR 0.58), while model validation resulted in unsatisfactory performance (NSE -0.06 and RSR 1.03). SWAT simulation at Sileng subwatershed scale creates 35 HRUs (hydrological response units) with mixed forest (FRST) being the widest land cover dominated by slopes >25-40% (steep) and >40% (very steep). Bush (PAST) is the narrowest land cover with > 40% slope dominance. Annual surface runoff that categorized as high is dominant in dry land annual crops (AGRR) and settlements (URBN) with slopes of 8% (flat) and >8-15% (sloping) covering an area of 499.47 hectares. On the other hand, annual surface runoff that categorized as low is dominant in mixed forest (FRST) with a slope of >40% covering an area of 694.81 hectares. The watershed rehabilitation area by PT Adaro Indonesia is dominated by low and medium surface runoff classes category