FUNDAMENTAL STUDY ON SPATIAL RESOLUTION OF TOPOGRAPHIC INFORMATION FOR RUNOFF ANALYSIS

Spatial resolution of topographic information gives a great influence to distributed runoff analysis. The objective of this study is to evaluate the effects of spatial resolution of DEM (Digital Elevation Model) on flood analysis with 1-D main flow channel. Kinematic wave propagation is simulated through real and imaginary river channel data sets having various resolutions. This study reveals that (1) Low resolution of DEM shortens delayed time of peak discharge, because smallhorizontal curves of river channel are omitted and channel elements become shorter;(2) Vertical curves in channel profile have also significant influence to discharge. An accuracy of discharge analysis greatly depends on the correlation between spatial resolution and wavelength of topographic vertical curve; and (3) Sufficient resolution is about 1/50 of the wavelength.