Flood modelling due to climate change impact in the Logawa watershed

Department of Civil Engineering, Faculty of Engineering, Jenderal Soedirman University, Purwokerto, Indonesia

^* Corresponding author: surosotsipil@unsoed.ac.id

Abstract

Rainfall change is one of the results of global climate change. It is required to analyse the impact of rainfall changes on flood risks. The aims of this research are (i) to model the watershed using the HECHMS hydrological model, (ii) to apply the scenario-neutral approach, (iii) to perform the frequency analysis using simulated discharges, and (iv) to determine the response and sensitivity of the watershed due to rainfall changes. This research uses a quantitative method using secondary data. The data required in this research are the watershed's geospatial and biogeophysical data. The simulation methods used in this model are the user Hyetograph Model, SCS Curve Number, Clark’s Unit Hydrograph, Recession Baseflow, and Muskingum Routing. The results of this research are (i) the hydrological model of the watershed with a percent bias score of 19.18% and an NSE score of 0.218; (ii) 130 total scenarios as the result of the RStudio using the scenario-neutral approach; (iii) the discharge result from frequency analysis with return periods of 1.1, 2, 5, 10, 20, 30, 40, 50, 100, and 200 years; and (iv) the watershed’s sensitivity with the average highest maximum discharge from November to April and the average lowest maximum discharge from May to October.