In the past few years, GIS emerged as a powerful risk assessment tool and is being put to use to assess risk to property and life stemming from natural hazards such as earthquakes, hurricanes, cyclones and floods. Manipulation, analysis, and graphic presentation of the risk and hazard data can be done within a GIS system, and because these data have associated location information which is also stored within the GIS, their spatial interrelationships can be determined and used in computer based risk assessment models. This assessment can be used by insurance companies to help them make decisions on their insurance policy rates, by land developers to make decisions on the feasibility of project sites, and by government planners for better disaster preparedness. A fundamental principal of Risk Assessment is that risk due to natural catastrophes such as earthquakes, hurricanes and flood, is location dependent, and that it can be assessed within an acceptable range of uncertainty if reliable historical and location specific data is available. Risk assessment of natural catastrophes has two components-hazard and vulnerability.
Hazard is location dependent.
For example a location which is surrounded by seismic faults and has a weak surface geology has a higher hazard potential than a location for away from faults and with strong surface geology. Similarly, hurricane, hazard at a location near the coast and with a flat, bare terrain is far higher than at a location which is inland and has a rugged terrain. Manmade structure respond to different perils in different ways, depending on the design of their structural systems and methods of constructions. Disaster preparedness programme in Andhra Flood and cyclones play havoc with irrigation processes in the coastal areas of Andhra Pradesh. On the other hand, the Rayalseema and Telenagana regions with semiarid to arid climatic conditions are frequently affected by droughts.