東海豪雨時の野並地区における浸水とその対策に関する考察

Abstract

東海豪雨によって名古屋市天白区野並地区で発生した浸水被害を対象とし, 浸水状況を再現するシミュレーションモデルを構築した.次に, このモデルを用いて, いくつかの想定シナリオのもとでの浸水シミュレーションを行い, 浸水被害の原因や対策について考察した.その結果, 計画規模を越えるような豪雨に対処するためには, 排水のネットワーク構造を考えた対策を考えねばならないことが明らかとなった.

A simple inundation simulation model is applied to the Nonami district in Nagoya City, and the causes and countermeasures for the urban flood in the Nonami district due to the heavy rainfall in theTokai region in 2000 are studied.The model estimates inundation stages with the continuity equation and the depth-volume relationship for the Nonami district generated from a 10m grid Digital Elevation Model. The computed maximum inundation depth shows a good agreement with the observed inundation depth. By using the model, inundation simulations are carried out under some scenarios. Findings from the simulations are that the maximum inundation depth does not change even if the pump system at the Nonami district worked without failure; the pump system needs more than 2.5 times capacity to cope with the heavy rainfall; and if the Nonami district does not have inflows from the adjacent basins, inundation damage is quite small. The simulation results indicate that a drainage system should manage a network of basin water movement in order to deal with a heavy rainfall beyond a design rainfall.