Journal of Natural Disaster Science

ASSESSMENT OF EVACUATION SYSTEMS FOR WATER OR MUD FLOODS: A COMBINED SIMULATION OF FLOODING AND THE ACTION OF RESIDENTS

Tamotsu TAKAHASHI
Professor, Disaster Prevention Research Institute, Kyoto University
Hajime NAKAGAWA
Associate Professor, Disaster Prevention Research Institute, Kyoto University
Motoi HIGASHIYAMA
Engineer, Maeda Construction Co. Ltd.
and
Hideki SAWA
Undergraduate Student, Department of Civil Engineering, Kyoto University

(Received 13 September 1990 and in revised form 11 January 1991)

Abstract

A method is presented that simultaneously simulates the overland flood flow caused by river bank breaching and the evacuating actions of groups of residents. This simulation method can also be applied to a mud flow. The validity of the simulation method first is shown for a relatively simple case using different conditions: various time lags between the commencement of a refuge and the bank breach, topographical conditions along the evacuation route, retardation of walking speed due to inundation and congestion, etc..

The model then is applied to actual basins. In the Ogura Basin, evacuation due to inundation by flood flow is simulated for various bank breach points and for various timings of the issue and propagation of information on advice or the order to evacuate. In some cases all the residents arrive safely at existing refuges, in others they are trapped by the flood on the evacuation route. For the Kamifurano Basin, the area and thickness of the deposit due to inundation by mud flow also are simulated and the safety of the refuges themselves is checked. We found that almost all the residents arrive at the refuges within 25 minutes and that some refuges are fooded above the second floor.

Key words

evacuation, evacuation order, evacuating action, simulation, flood, mud flow