Ko MIKAMI
Development of a Distributed Hydrological Model Taking Into Account of River Cross-Section
Minjiao LU
Distributed Hydrological Model is one of the runoff analysis model. This model deals with geographic and weather information that is temporal and spatial by dividing the watershed to a mesh. The calculation result of the flow rate of using this model is highly reproducible, although this model is time-consuming to prepare the parameters and input data. However, the reproducibility of the water level is usually low. This is caused by the assumption that river channel in the model in determining the flow rate is a wide rectangular cross section that river width is sufficiently larger than the water depth. This tendency is remarkable in section with severe water level change such as through alternately the stenosis and basin section. There is a stenosis section in Tategahana of Nagano Prefecture, which is included in the target watershed of this study. Information of water level such as the flood level is required for evacuation of residents at the time of flood. The purpose of this study is to improve the reproducibility of both flow rate and water level by building a model using surveyed river cross-section.
For calculation using river cross-section, the flow area, flow velocity and flood celerity are tabulated against the water level. And the use of these tables makes it possible to derive water level, celerity from flow rate.
Calculation results for the July 2006 flood in Shinano river basin confirm the reproducibility of the newly constructed model. It is shown the accuracy of water level improved significantly
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