Pemodelan Hujan Aliran Menggunakan Software HEC-HMS Berdasarkan Data Curah Hujan Satelit CHIRPS (Studi Kasus DAS Kalibaru)

Abstract

The flood occurrences in Kalibaru Wetan Subdistrict are unavoidable, thus necessitating an understanding of the interaction between rainfall and water flow. This comprehension is crucial for early warning systems against rainfall that poses a flood risk. Despite frequently facing a shortage of conventional rainfall data, this study attempts to utilize CHIRPS satellite rainfall data (with a resolution of 0.05° x 0.05°) as an alternative to predict the flow in the Kalibaru Watershed. The methods involve Green and Ampt, and SCS-CN for the volume runoff model, Clark UH, and SCS UH for the direct runoff model, Constant Monthly for the baseflow model, and Muskingum-Cunge for the routing model. The correlation between CHIRPS rainfall and observations from 2011 to 2020 is 0.508. The results of rainfall modeling using CHIRPS satellite data in 2019 show an NSE value of 0.383, P Bias of 5.45%, and R2 of 0.4455. In contrast, for the observation rainfall model, NSE is 0.577, P Bias is 18.8%, and R2 is 0.5998 when using the Clark UH method, indicating acceptance only in the observation rainfall model, while the CHIRPS model is not accepted. On the other hand, results using the SCS UH method show lower values compared to Clark UH. Therefore, it can be concluded that for the characteristics of the Kalibaru Watershed, the recommended method is Clark UH compared to the SCS UH method.