Author(s): Hyejin Ku; So Kazama; Masaki Sawamoto
Linked Author(s): So Kazama
Keywords: Distributed model; Hydrograph; Uncertainty; Scale; Rainfall; Resolution; Topology
Abstract: Inevitable uncertainty of a distributed model makes us have a doubt whether data, parameterization, calibration and validation employed in a simulation are appropriate to the model. The present study focused on the uncertainty from data and investigated the effects of resolution and scale on hydrograph. A grid-based rainfall-runoff model was applied to five imaginary catchments with different areal extents. We could investigate the effect of topology and rainfall resolutions by employing spatially variant and invariant rainfall types. Especially, storage coefficients conducting interflow and baseflow were defined as a function of grid size to assess the effect of topologic resolution. Hydrographs for catchment with 100, 2500km2 showed that coarser resolution could bring poor result in the simulation for small catchment. There is, however, almost no difference of hydrographs for resolutions owing to the storage coefficients expressed as grid size. Error contour maps for relative volume error and model efficiency calculated assuming that the result with finest resolution was error-free were drawn with axes of resolution and scale. The contour maps indicated that finer resolution was required for simulation of smaller catchment and the gradient of contour was likely to high for small catchment. The comparison between two rainfall types presented that the topology resolution had more influence on hydrograph than rainfall resolution.