Estimation of the Nash Model Parameters Based on the Concept of Geomorphologic Dispersion

This study presents a new method to estimate the Nash model parameters on the basis of the concept of geomorphologic dispersion stemming from spatial heterogeneity of flow paths within a catchment. The proposed method is formulated by including physically meaningful characteristic velocities for channel and hillslope and also takes account of the effect of complex interactions between channel and hillslope hydrological behaviors on catchment responses. We applied the proposed formulas to the Bocheong watershed, an experimental area established under the International Hydrological Programme (IHP) in Korea, with several storm events to assess the individual effect of channel and hillslope on hydrological responses in the study site. The characteristic velocities were estimated by topographic data based on a 20×20 m digital elevation model (DEM) from a 1∶25000-scaled topographic map and statistical features of the historical events. We then calculated the Nash model parameters by substituting the estimated ...