Rainfall-runoff research is a field of study that focuses on the processes by which precipitation on the Earth's surface transforms into runoff, which then flows into rivers, lakes, and oceans. This research area seeks to understand the complex interactions between rainfall, surface runoff, infiltration, evaporation, and groundwater recharge. By studying rainfall-runoff processes, researchers can better predict and manage water resources, evaluate the impacts of land use changes and climate variability, and assess the risks of floods and droughts. Methods used in this research area include field observations, hydrological modeling, remote sensing, and data analysis techniques.