SR-1/97-98 : Hydrological aspects of flood disaster management

Abstract

Flooding is the major disaster bringing greater damage than any other disaster. Flooding remains a major unresolved problem and is a global phenomenon. There are climatological and part-climatological causes of flood. Several basin conditions, network conditions and channel conditions intensify the flood. Indirect causes like man's activity may also cause flood. The effects of disastrous flood are ; inundation, damage to transport and power supply, deterioration of surface water and ground water quality, and geomorphological changes. An effective flood disaster management (FDM) is essential. FDM is a multidisciplinary subject. Hydrology plays an important role in FDM. FDM is defined as the enhancement of the total productivity of the flood plain wherein losses are only a part of it. Present day trend in FDM moves away from structural measures to non-structural solution. FDM requires complicated computational methods. Flood plain zoning is one of the common techniques in FDM. The three approaches are a)Modelling susceptibility to flood damage and disruption b)Modifying flooding and c)Modifying the impacts of flooding. The areal inundation of a given flood depends on the flood plain character and the hydrodynamics of the flow. In case of coastal regions, effective methods to predict the effect of tidal rivers are to be adopted. Hurricane frequency are still to improve to have adequate lead time for issuance of warning and necessary evacuation. Cyclone warning and weather satellites are used for forecasting and monitoring. Geostationary satellites are in use. Satellite data can be used for preparation of flood inundation maps. The data bank for an optimal flood disaster management consists of values of cross-section and flood plain, discharge and water level, flood inundation map, flood loss, river bank and breach, sediment, morphological change, and land slide. Mega-floods are also caused by dam failures. Though many mathematical models are available, issues like dam failure mechanics and aggradations and degradation are still open. Different hydrological aspects concerning flood disaster management need furthur research.