Discharge simulation in the Huaihe River using fine resolution downscaled experimental data derived from GAME data product
Roshan K. Shrestha (1), Yasuto Tachikawa (2), Kaoru Takara (2)
(1) Graduate School of Urban and Environmental Engineering, Kyoto University, Japan
(2) Disaster Prevention Research Institute, Kyoto University, Japan
There is a large scale-gap between the atmospheric model’s output and the need of hydrological simulation tools. The simulation of spatial rainfall field based on non-homogenous random cascade method can be a powerful tool to fill this gap by disaggregating the large-scale data into a scale smaller enough to apply in hydrological simulations. We developed multiplicative random cascade HSA method and applied it to disaggregate the GAME Reanalysis 1.25 degree precipitation data into 10 arc-minute spatial resolutions. And thereafter applied the disaggregated data into the MaScOD model to simulate the runoff discharge. The disaggregated data has produced satisfactory results for three differently sized study catchments inside the Huaihe River basin. Further we aggregated the fine resolution data into a coarser resolution to investigate the suitable scale of input data for the distributed hydrological model. This part of study has reinforced the concept of IC-Ratio (the ratio between grid cell area and the catchment’s area) (Shrestha et al., 2002) to be higher than 1:10 in order to obtain a satisfactory result of discharge simulation using the distributed input. This finding suggests that the needed data resolution depends upon the catchment area. For a smaller catchment area, the resolution should be finer, but a coarser resolution data can well serve the simulation need for a larger catchment. This finding may help atmospheric modeler to understand the extent of data need for hydrological simulation.
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Roshan K. Shrestha
03-Aug-04-16:46:34
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Disaster Prevention Research Institute, Kyoto University