GIS-based improvement of C. O. Clark method for simulating watershed-scale overland flow in the Chinese Loess plateau

Traditional static methods have disadvantages of being lack of considering the spatiality of the data and new developments in spatial techniques (e.g., GIS) can help us in dealing with the spatiality problems. In this research, a semi-lumped conflux model (i.e., C. O. Clark method) is modified to be a semi-distributed conflux model by GIS- assisted partitions of spatial variables influencing the net precipitation into a spatially homogeneous watershed. Specifically, the spatial attributes of the dynamic processes were depicted through GIS-assisted DEM delineation of watershed geomorphology and spatiality of the factors modulating the hydrographs are considered by the adjustment factor K. Our results show that the GIS-assisted and spatially-improved Clark model generated more realistic results than the lumped original model, implying that the spatiality of the hydrogeomorphic factors that modulate the net precipitation plays a significant role in surface runoff generation in the entire watershed and thus in conflux processes in the outlet even within a small watershed.