Flood Hazard Web GIS in Japan Developed with TatukGIS SDK

The web mapping application enables anyone in the vicinity of a reservoir to understand in advance the flooding impact if the reservoir fails - such as due to an earthquake or heavy rainfall during a typhoon. Citizens can easily understand if their home or business is at risk, how much time following a reservoir collapse before flood water reaches their location (i.e., time available to evacuate), projected depth of the inundation (represented by color gradients), and optimal evacuation path to higher ground and emergency shelter.

The territory of Higashihiroshima City contains 1,821 priority-level agricultural reservoirs, more than any other city in the Hiroshima Prefecture, and approximately 2,200 smaller irrigation ponds. According to the Higashihiroshima Agriculture and Forestry Division, 48 agricultural reservoirs in Hiroshima Prefecture collapsed in 2018, sometimes resulting in deaths. It is hoped this application will help citizens become more aware in advance of the risk posed by nearby reservoirs and be better prepared.

A simulated flood presentation is available for each reservoir using unfavorable assumptions that the reservoir is full and the collapse is instantaneous. For example (refer to the following image), a sudden collapse of the Senzoku Reservoir located in Saijo Town ward would result in flood water reaching National Highway 375, approximately 2 kilometers to the west, in approximately 15 minutes. Sections along the highway would become flooded to a depth of 2 to 3 meters.