Flash Flood Disaster and Flash Flood Warning in China

Flash flood has become an increasing threat to the people in the world, and this problem is especially prominent in China. China is blessed with a rich natural environment. Such a natural environment, however, presents severe natural and meteorological conditions. With complex topography, vulnerable geology and monsoon climate, China is highly susceptible to flash floods triggered by torrential rainfalls.

To prevent such destructive disasters, massive flash flood disaster prevention efforts have been made not only in China but also in other countries in the world. But, the results are not so fruitful because the flash flood prone area is numerous in number and extends over a vast area, an enormous amount of time and cost are required to make all the hazard areas safe with the installation of disaster prevention works. For this reason, when promoting flash flood prevention measures, versatile non-structural measures should be taken in addition to structural measures such as installation of disaster prevention works. Non-structural measures include the designation of a flash flood disaster hazard area and the development of a warning and forecasting system appropriate for those areas.

This paper provides some general information about flash floods such as debris/mud flow in China, and describes two kinds of non-structural measures being taken to prevent such disasters. The development of hazard map of flash floods, and the construction of a warning and forecasting system appropriate for flash flood prone areas will be introduced here. Geologic, topographic, hydrologic, engineering and socio-economy data are used to map flash flood vulnerable areas, providing decision makers with valuable information to manage development and zoning in flash flood prone areas. In addition, flash flood warning systems can be developed by setting up standard rainfall index which may be used as a threshold model for forecasting important factors which provoke such disasters. This model can provide advance notice of potentially hazardous conditions in vulnerable areas to assist decision makers in decision making process.