Abstract
A runoff model was applied to investigate outflow control effect of on-site storage and soil improvement for improving infiltration capacity. We calculated overflow amount of each manhole before and after measures at the Zenpukuji river in Tokyo using four types of hyetograph (occurrence probability 1/100). The result of simulation suggested the following: 1) large overflow amount and wide area of overflow was occurred in short term concentration rainfall, 2) effect of on-site storage and soil improvement was high in long term rainfall, although depression effect was different for each points, 3) effect of countermeasures was constant for short distance upstream and downstream form the measures point and reduction effect for upstream was high at place occurring overflow due to backwater, 4) effectiveness of countermeasures could be enhanced to intensively-introduce runoff control measures for sites overflow volume was large.
