Ways in which remote sensing and GIS help in disaster mitigation and management

Geographic Information System (GIS) is a computer based application of technology involving spatial and attributes information to act as a decision support tool. It keeps information in different layers and generates various combinations pertaining to the requirement of the decision making. GIS has emerged as an effective tool in management of disasters since, geo-spatial data and socio-economic information need to be amalgamated for the better decision making in handling a disaster or to plan for tackling a disaster in a better way. GIS could be utilized by the different line departments and agencies who are stakeholders in the disaster management process. Some basic hardware like computer system, printer, network systems, along with GIS software are required to set up the GIS in any organisation.
The prime objectives of developing the GIS database are to help disaster managers at local and regional levels for:

1. Pre-disaster planning and preparedness
2. Prediction and early warning
3. Damage assessment and relief management

GIS combines layers of information on various themes to enable the managers to take the most appropriate decisions under the given circumstances. For disaster management, a GIS database could be a useful managerial tool for the reasons listed below:

1. Disaster Managers could generate maps both at micro and macro level indicating vulnerability to different extents under different threat perceptions.
2. Locations likely to remain unaffected or remain comparatively safe could be identified.
3. Alternate routes to shelters, camps, and important locations in the event of disruption of normal surface communication can be planned
4. Smooth rescue and evacuation operations could be properly planned.
5. Rehabilitation and post-disaster reconstruction works could be properly organized.
6. Locations suitable for construction of shelters, godowns, housing colonies, etc. can be scientifically identified.
7. Areas where no construction should be taken up or existing habitations require relocation, could be identified.

Department of Space (DOS, India) has embarked upon the Disaster Management Support to extend the benefits of the aerospace technology for the resolution of disaster management in the country. The Decision Support Centre (DSC) established at National Remote Sensing Centre (NRSC) is the single window delivery point for aerial and space enabled inputs together with other important data layers for its use in disaster management of pre-disaster, during-disaster and post-disaster phases. The natural disasters being addressed are  Flood, Cyclone, Agricultural Drought, Forest Fire, Earthquake and Landslide. Depending upon the satellite pass, cameras are tilted and data is acquired and analysed. The information is monitored on a regular basis for damage assessment. DSC has provision to mobilize aircraft equipped with Synthetic Aperture Radar (SAR), Air-borne Laser Terrain Mapping unit (ALTM) and High Resolution Digital Camera for obtaining aerial data. DSC is working on space inputs for long-term disaster mitigation and rehabilitation. Use of remote sensing data for various natural disasters is discussed below:

FLOOD: To keep watch on the flood situation in the country through hydrological and meteorological information from various sources, mapping & monitoring of major flood/cyclones with the satellite data from optical and microwave satellites, Generation of flood maps showing flood. The most flood-prone areas in India are the Brahmaputra, Ganga and Meghana River basins in the Indo-Gangetic-Brahmaputra plains in North and Northeast India. ISRO/DOS is playing a vital role in supporting the flood management activities, by providing space as well as aerial remote sensing based services and products. Using satellite data from Indian Remote Sensing Satellite (IRS) System and from foreign satellites, the impact of floods in the country is assessed. The services provided in this context include:

1. Near Real Time Flood Mapping and Monitoring
2. Flood Damage Assessment
3. Flood Hazard Zone Mapping
4. River Bank Erosion Mapping and
5. Mapping changes in the river course

CYCLONES: Cyclones are wind-systems of relatively low pressure which spiral inwards towards a centre in the lowest atmospheric levels and cause immense destruction and loss of life when they strike coastal areas. Satellite communications provide an effective mechanism for real-time dissemination of information and early warning besides establishing communication link after cyclone hit. Earth observation satellites enable continuous monitoring of atmospheric as well as surface parameters. Information acquired by satellite remote sensing covers wide area, periodicity and spectral characteristics and especially in the easiness to compare the data before and after a disaster.

DROUGHT: Agricultural drought assessment using space technology inputs has been operational in India since 1989, through a project 'National Agricultural Drought Assessment and Monitoring System (NADAMS)'. NADAMS provides near real-time information on prevalence, severity level and persistence of agricultural drought at regional and local levels through remote sensing.

FOREST FIRES: Indian Remote Sensing Satellite images were acquired and processed to monitor the forest fire incidence. The Decision Support Center (DSC) is established at National Remote Sensing Centre (NRSC) as part of Disaster Management Support Programme of Department of Space (DOS), for working towards effective management of disasters in India. A comprehensive Indian Forest Fire Response and Assessment System (INFFRAS) is invoked under DSC activities of NRSC, which integrates multi-sensor satellite data and ground data through spatially and temporally explicit GIS analysis frame work. This system provides information on:

1. Fire alerts
2. Fire progression
3. Burnt area assessment and
4. Forest fire mitigation plans