MAPPING
Cyclone & Flood Hazard Classes of Geographical Landscape Class - I Highly prone to floods
due to landing of tidal surge (Flooding by the tidal wave) and inundation by heavy rainfall. The areas and settlements located in this class-zone are under direct threat of the tidal waves. Class – II Moderately prone to tidal surge but highly prone to floods due to heavy rains (insitu /
catchments). The areas and settlements in this class-zone are less threatened by the tidal waves but are prone to submergence due to heavy rains for a longer duration as most of these fall in low lying areas. Class – III The areas and settlements are prone to floods caused by both tidal wave and/or heavy rainfall but the duration of submergence is short. Class – IV Highly prone to floods caused by heavy rain (in situ/catchments). The areas and villages in this class, though not threatened by the tidal waves but highly prone to floods caused by the rains both in the local area as well as in the catchments. The duration of water logging depends on the condition of the drains. Class – V Moderately prone to floods due to heavy rains (in situ/catchment) as the duration of water logging in areas under this class is shorter. Class – VI The areas and villages falling in this class are highly prone to floods and water logging due to heavy rains insitu. Class – VII Areas under this class are moderately affected by the heavy rains in situ and the flooding/water logging is for a shorter duration Class – VIII Areas under this class are highly prone to floods caused by overflowing of the rivers Class – IX Moderately prone to floods due to rise in river level. Class – X Prone to floods due to local problems such as breach in the canal and/or choking of drains Class – XI Partially prone to floods due to extraordinary rains coupled with cyclones. Class – XII Generally not prone to floods Class – XIII Safer places. The above classifications provide a base for mapping hazards with different intensities in detail. For the purpose of preparedness and disaster mitigation planning, all the thirteen classes can be grouped into four categories of
vulnerability as under. 1. Very high vulnerability The areas and villages which are highly threatened by both, the tidal waves and the floods caused by heavy rains insitu. This category includes all areas/villages falling in class – I to III 2. High Vulnerability The areas and villages highly prone to floods due to heavy rains in situ / catchments areas as well as improper drainage system. This category includes all areas / villages falling in class IV to VIII 3. Moderate Vulnerability The areas affected by the floods due to overflowing of rivers, breach in canal, choking of drains, etc. In this category the areas / villages falling in the class VIII to X, are included. 4. Low Vulnerability All areas falling under class XI – XIII are included in this category as these areas are generally safe.