Mitigation of Climate Change Impact by the Scenario of RCP 2.6 and RCP 8.5

This study aims to analyze the impact of climate change on hydrological characteristics and flood discharge in the Noelmina and Benanain River Basins, East Nusa Tenggara Province, under the Representative Concentration Pathway (RCP) 2.6 and RCP 8.5 scenarios. The hydrological modeling was conducted by using the HEC-HMS software, based on the CHIRPS satellite rainfall data and it is validated against ground station observations. The model was calibrated by using the Nash-Sutcliffe Efficiency (NSE) and correlation coefficient (R) to ensure simulation reliability. The simulation results indicate that climate change significantly affects flood discharge in both basins. Under the RCP 2.6 scenario, peak discharge tends to decrease due to the higher evapotranspiration, whereas under the RCP 8.5 scenario, peak discharge increases by approximately 10–30% compared to current conditions. These findings reveal that climate change may intensify the extreme flood risks and reduce water availability during dry seasons. Therefore, adaptive water resource management strategies are required, including the reservoir capacity enhancement, land conservation, and climate-based water management optimization for sustainable river basin development.