Performance of GPM-IMERG satellite precipitation for rainfall-runoff modeling in Indonesia

Accurate discharge predictions are essential for effective water resource management, including irrigation, drinking water supply, hydropower, reservoir management, environmental flow, and flood assessment. Satellite precipitation data, such as GPM-IMERG, offers a viable solution for estimating river discharge, especially in ungauged or sparsely gauged watersheds. This study evaluates the use of GPM-IMERG data in the HEC-HMS hydrological model to predict discharge in the Mayang Watershed, Jember Regency, Indonesia. The study employs the Arithmetic, Polygon Thiessen, and Isohyet methods to analyze rainfall distribution. Results indicate that the Polygon Thiessen method, when paired with GPM-IMERG data, provides more reliable precipitation estimates due to its consideration of rain gauge proximity. Calibration and validation confirm the superiority of GPM-IMERG data over traditional observational data, particularly under high-flow conditions. Despite some limitations in detecting low-intensity precipitation, GPM-IMERG outperforms other satellite products like TRMM in terms of accuracy. Sensitivity analysis highlights the significant influence of parameters such as curve Number and time of concentration on model outcomes. Further research should explore emerging rainfall data products to improve hydrological modeling accuracy.