A linear semi-distributed conceptual model for flood estimation

A linear semi-distributed conceptual model is presented to represent surface-runoff generating and routing processes. Based on a natural river network, a basin is divided into a number of sub-watersheds. Outflow draining out of each of the sub-watersheds is computed using the Nash model with a few cascade reservoirs. The number of cascade reservoirs is determined based on the size of a watershed. The storage coefficient of the Nash model is estimated using the kinematic wave method that takes into account the physical characteristics of a watershed (surface roughness, slope, etc.). Velocity of flood wave travelling along a river channel is estimated using the Kraven empirical equation on the basis of channel slope. Applicability of the model is tested with the data from an actual basin to estimate flood hydrographs. The computed flood hydrographs show a good correspondence with observed ones.