Abstract
For the evaluation of flood mitigation function of irrigation ponds, this paper analyzes the relationship between the flood mitigation ratio and delay ratio of the time of flood concentration, based on the hydrological records in the irrigation pond in Osaka Prefecture. Further, A new idea and evaluation method of the concentration time is suggested, and defined as “maximum time contributing to peak discharge”. New method of the flood mitigation value of irrigation ponds using the properties of the pond construction and the rainfall pattern was developed based on hydrological observation at 19 ponds and numerical simulations under several conditions. Results showed that the new method could sufficiently represent the flood mitigation value to the actual flood events. Therefore, it was expected that it can evaluate the flood mitigation function in many irrigation ponds.
