His research interests focus on the hydrological and geomorphic processes at the small watershed scale by integrating field investigations into simulation modeling. His recent research includes simulating overland and tunnel flows using the Topog model, quantifying the geomorphic and hydrological roles of tunnel flows in drainage development, investigating soil crusting process and its impact on soil moisture and runoff generation, and examining gully erosion and development. Tongxin teaches courses in physical geography, hydrology, environmental conservation, and environmental applications of geographic information science (GIS).