RESEARCH ON FLOOD CONCENTRATION TIME BY USING A DISTRIBUTED HYDROLOGICAL MODEL

Abstract

The objective of this study is to investigate the relationship between flood concentration time and geograpgical and hydraulical characteristics by using a distributed hydrological model. The distributed model makes it possible to route the runoff generated over the whole catchment without any simplification. This model is applied to Uono river basin of 362km^2. The flood concentration time of Uono river basin itself and its 14 subbasins with different drainage areas are derived by driving the model with constant rainfall, 15mm/hr and 60mm/hr. Furthermore, this procedure is applied to virtual basins generated by digitally enlarging or shrinking above basin and subbasins. The flood concentration time of all these basins are plotted against geographical index and hydraulic index induced based on kinematic wave theory. Finally, a formula to estimate flood concentration time is proposed. It is shown that this formula represent the flood concentration time of Uono river basin and its 14 subbasins very well.