A RAINFALL-RUNOFF MODEL BASED ON THE WATERHED STREAM NETWORK

limited data, The model parameters must have a physical signifi- cance, be convenient to obtain and their number should be small, The framework of a model meeting these objectives is proposed and is based primarily on the geomorphologic characteristics of the stream network obtainable from maps or from aerial photographs. There is analytical and experimental evidence that hydrographs are dominated by direct runoff from very short overland flow paths from precipitation on transient, near channel wetlands. This wetland area is dynamic in the sense that it varies in terms of the history of the excess of the precipitation over the "B" horizon permeability, The distribution of the dynamic contributing area along the main stream is obtained under the assumptions that the velocity of flow along the stream network is uniform, that the drainage density is a constant within a given watershed and that the first order streams are uniformly distributed in the basin, The runoff from the dynamic contributing area is then routed through the synthesized stream network to obtain the direct runoff at the basin outlet,