Rainfall-Runoff Hydrological Modeling Using Observed and Remotely Sensed Rainfall Data for Sustainable Watershed Management over Modjo Catchment, Central Ethiopia: Insights from HEC-HMS Model

The primary obstacle in making accurate runoff predictions in the catchment is the unavailability of precise rainfall measurement data. The objective of this study is to apply the HEC-HMS to estimate runoff using observed and satellite precipitation products over the Modjo catchment and measure and compare the performance of each simulation. The study considered two commonly used gridded precipitation products: CHIRPS. In the HEC-HMS model setup, the study used the SCS Curve Number, SCS Unit Hydrograph, and the Muskingum method for Loss, transform, and routing model, respectively. Hydro-meteorological data, collected daily, were compiled and prepared for the process of model calibration (spanning2010-2019) and validation (2020-2023). Results showed that NSE, R2, and PBIAS values become 0.842, 0.85, and -2.99 for observed rainfall products and 0.711, 0.72, and +5.6 for CHIRPS rainfall products during calibration and 0.751, 0.78, and -3.112 for observed rainfall products and 0.622, 0.64, and +7.99 for CHIRPS rainfall products during validation. The estimated peak flood discharge simulated with observed, and CHIRPS data was 288.9 m3/s, and 369.2 m3/s, then compared with the observed stream flow of 248.1m3/s. The model results have revealed that global precipitation products have showcased a promising and observed precipitation an effective performance in simulating runoff over the Modjo catchment and are recommended for further investigation to improve the accuracy.