Surface flow refers to the movement of water across the surface of the Earth, such as rivers, streams, and runoff from precipitation. This research area focuses on studying the dynamics, patterns, and behavior of surface water flow in various landscapes and environmental conditions. Researchers in this field aim to understand the factors that influence surface flow, such as topography, vegetation, climate, and land use, in order to improve water resource management, flood prediction, and ecosystem conservation efforts. Studies in surface flow often involve field measurements, remote sensing techniques, and computer modeling to analyze and predict the movement of water across the Earth's surface.