GIS@development May - June 1999; Use of GIS related technologies for managing disasters in India: An Overview

Use of GIS related technologies for managing disasters in India: An Overview

Dr. Vinod K. Sharma
Professor Environment & Natural Disaster Management
National Center for Disaster Management
Indian Institute of Public Administration
New Delhi

The Indian subcontinent is vulnerable to Drought, Floods, Cyclones and Earthquakes, though Landslides, Avalanche and Bush fire too frequently occur in the Himalayan region of northern India. Among the 31 total States / Union Territories in the country, 22 are disaster prone.

Among all the disasters that occur in the country, River Floods are the most frequent and often the most devastating. The cause for floods is chiefly the peculiarities of rainfall in the country, out of the total annual rainfall in the country 75% is concentrated over a short monsoon season of three to four months. As a result there is a very heavy discharge from the rivers during this period causing widespread floods. As much as 40 million hectare of land in the country has been identified as flood prone. An average of 18.6 million hectare of land is flooded annually. Floods are caused mainly in the Gang - Brahmaputra - Meghna basin which carry 60% of the nation's total river flow.

Earthquakes are considered to be one of the most dangerous and destructive natural hazards. The impact of this phenomenon is sudden with little or no warning, making it just impossible to predict it or make preparations against damages and collapses of buildings and other main-made structures. About 50-60% of total area of the country is vulnerable to seismic activity of varying intensities. Most of the vulnerable areas are generally located in Himalayan and sub-Himalayan regions, and in Andaman and Nicobar Islands.

Drought is perennial feature in some states of India. 16% of the country's total area is drought prone and approximately 50 million people are annually affected by droughts. In fact drought is a significant environmental problem too as it is caused by less than average rainfall over a long period of time. In India about 68 percent of total sown area of the country is drought prone. Most of the drought prone areas identified by Govt. of India lie in the arid, semi arid and sub-humid areas of the country.

India has a very long coastline of 5700 km. which is exposed to tropical cyclones arising in the Bay of Bengal and Arabain Sea. The Indian Ocean is one of the six major cyclone-prone regions of the world. In India cyclones occur usually between April and May, and also between October and December. The eastern coastline is more prone to cyclones as about 80% of total cyclones generated in the region hit there.

In India, traditionally the approach adopted in managing disasters has been towards reactive with activities focussed on Disaster Relief. The approach was based on experiences of severe famine that struck several parts of the country in the early part of this century.

It is only in recent decades that there is perceptible shift in focus from disaster relief to disaster preparedness and prevention. The shift in approach has brought in a significant positive change even though the multitude and frequency of disasters in the country has increased.

Mitigation And Prevention: New Approaches for A Safer Future

In disaster situation, a quick rescue and relief mission is inevitable, however, considerable damage can be minimized if adequate preparedness levels are achieved. Indeed, it has been noticed in the past that as and when attention has been given to adequate preparedness measures, the loss to life and property has considerably reduced.

Preparedness measures such as training of role players including the community, development of advanced forecasting systems, effective communications, and above all a sound and well networked institutional structure involving the government organizations, academic and research institutions, the armed forces and the non-governmental organization have greatly contributed to the overall disaster management in the country. This can clearly be seen from the various instances of reduced damaged from disasters due to better preparedness and coordinated inter-agency response.

In 1991, government officials of Andhra Pradesh were able to implement a previously planned programme to evacuate 600,000 people from the path of an approaching cyclone within 52 hours. This was possible because the results of meteorological forecasts and warning were communicated through a combination of advanced and traditional channels to people conversant with the preparedness plan from earlier community exercises instituted after the devastating cyclone of 1977. Fatalities numbered less than one-tenth of the more than 10,000 people who perished in the previous cyclone 13 years before.

Such good practices are result of the heightened awareness and sensitivity towards communities at risk. The approach of reducing community vulnerability for reducing disasters has paid rich dividends. The first step in this direction has been of identification of vulnerable communities. Those communities periodically exposed to natural hazards, and within them those with low levels of coping powers, such as economically weaker sections, are the first focus of preparedness efforts. Marginal sections of rural communities and dwellers of informal settlements and slums in urban areas fall within this class.

Science & Technology Applications in Disaster Management

The changing trends have opened up a large number of allied questions, such as those of adequate availability of scientific and technological resources and skills to reduce disaster risks. Two major areas with vast potential for use of scientific and technological tools towards disaster risk reduction are Disaster Mapping and Search and Rescue (SAR) operations.

Disaster Mapping

Disaster mapping is a tool for assessing, storing and conveying information on the geographical location and spread of the effects, or probable effects of disasters. This is primarily a pre-disaster preparedness stage activity that needs to be highly specific, accurate and comprehensive.

The problem with traditional manual maps is that they are tedious and time consuming to prepare, difficult to update and inconvenient to maintain. Therefore, nowadays remote sensing is emerging as a popular means of map preparation, and Geographical Information Systems (GIS) can be used for storage, analysis and retrieval. Under remote sensing techniques, maps can be prepared using satellite data or aerial photographs, and are then digitized and stored on computers using GIS software. Once this is done, they can be retrieved and viewed on the computer any time. They can easily be enlarged or reduced, and even printed.

Disaster maps usually show risk zones or disaster impact zones. These are graded areas that would be affected progressively as the intensity of the disaster increases. These could include flood zone maps, seismic zone maps, industrial risk zone maps etc. A number of such maps may be overlaid on a base map of the area to give a composite disaster map that covers the risk of a number of disasters.

Mapping Prominent Disaster Prone Areas Drought

Drought relief management efforts have been greatly helped by remote sensing and disaster mapping techniques. Early warning of drought conditions will help to undertake contingency agricultural strategies and to organize relief where and when it is most needed. Targeting of potential ground water sites for taking up emergency well digging programmes have been made possible by the use of satellite data. the success rate of such wells had been significantly higher than when using ground methods alone. The first phase of the Drinking Water Mission consisted of district-wise groundwater potential maps is using high resolution Landsat/IRS data.

Long term drought proofing programmes calling for base-line information on the natural resources of the district have been greatly helped by the use of satellite data. in complement to the drought monitoring project, an integrated study to combat drought was taken up by Department of Space, Govt. of India, in collaboration with concerned State Governments in 21 districts in different states of the country. The objective was to ensure action plan packages as permanent solutions for combating drought in the drought prone districts. This covered management of water resources, agricultural and land resource, fodder resources, and integrates natural resource physical data base and socio-economic and demographic data base. Data from IRS satellite on 1:50,000 scale was use to generate resource data.

Resource maps such as soil, land-use and hydro-geomorphology was prepared using IRS data on 1:50,000 scale. Other maps such as slopes, drainage and watershed, transport network and settlement location and rainfall data were prepared from the secondary data available on Survey of India topographical sheets and with the Census Department. The socio-economic data were collected from the respective district administrations. The conventional resources of information, socio-economic and demographic data were integrated with the resource data obtained from the IRS satellite imagery in order to prescribe appropriate landuse, fodder and water management practices.

Floods and Cyclones

Satellite data can be used very effectively for mapping and monitoring the flood inundated areas, flood damage assessment, flood hazard zoning, and post-flood survey of river configuration and protection works. Near real time flood mapping was performed in the year 1986 in respect of the unprecedented historic Godavari floods, as well as floods that occurred in parts of Ganga basin lying in Bihar and Uttar Pradesh. This was continued during the flood period of 1987 in respect of various rivers like Ganga, Ghagra, Kosi, Gandhak, Mahananda, Brahmaputra, Teesta, Jhelum etc.m in different parts of the country. (ref. 1)

The cyclone of May 1990 over Andhra Pradesh coast and the resulting flood damage was mapped using satellite data. floods in Jhelum and Bramaputra rivers and in Orissa State during 1992 were mapped and information was sent to central/state authorities. Flood relief management was helped by information on areas inundated, marooned villages, impact on transportation network and damage to crop lands. Recent availability of better satellite data has helped flood mapping inspite of cloud cover. These data were used extensively (for the first time in the world) for flood mapping in 1993 season in Barhmaputra, North Bengal and Punjab floods. Floods in Jhelum and Kosi have also been mapped.

Efforts are also being made to compute the flood damage in various parts of the country by combining remotely sensed data and conventional ground data. a pilot project is under progress in a part of Brahmaputra Basin. An analysis of database on flood inundation during successive years can help to delineate areas, susceptible to floods of differing magnitudes. Drainage congestion as well as duration of flood inundation has been studied along Kosi river based on sequential satellite imagery to help effective flood plain management. Preliminary flood risk zone maps along Kosi and Brahmaputra rivers have been made using multi-year satellite imagery corresponding to differing flood magnitudes and return periods. This would provide valuable inputs to regulate flood plain land use.

Embankments and spurs, while offering protection, also generate complacency leading to large scale damages in case of breaches. High resolution satellite data has been used to map post flood river configuration in order to identify vulnerable reaches of embankments to enable corrective action. Erosion prone areas along the Brahmaputra river have been identified through multi-year satellite data to delineate river reaches for flood protection works.

Volcanic Eruption and Fires

Andaman Archipelago Islands lie in the seismo-tectonically active belt and form the converging plate boundary of Indian ocean. There are only two known active volcanoes in India-Narcondum and Barren Islands, located in Bay of Bengal about 130 km North-East of Port Blair. The Barren Island volcano remained dormant for nearly 200 years and erupted in March 1991 and continued till November 1991. The volcanic eruption was monitored using Multi-date satellite data of both day and night passes.

The volcanic vent temperature was estimated at 1200 degree centigrade and the vent position and recent lava flows were later monitored with multi-date data. damage to the dense evergreen forest has been detected.

Satellite imagery in the infrared regions and actual ground/aerial photographs have been employed to map areas damaged by forest fires. The data has been used to study and map a number of forest fires and to monitor the vegetation regeneration over burnt areas. The radiance in the thermal band was most suitable to map burnt areas. The 11 day repeat cycle provided by the Indian IRS satellites has been found to be extremely valuable in monitoring the forest fires in the tropical countries as demonstrated in the case of Nagarhole reserved forest in South India.

Earthquakes

Earthquake phase data collected by the National Seismic Telemetry Network for the past one hundred years were analyzed using a computer, and epicentral parameters were determined. Most of the epicentres tend to cluster along the plate boundary where the Himalayan Collision Zone was formed.

Earlier, the Peninsular India was considered free from seismic disturbances. However, the recent seismic activity in the Peninsular Shield area has sown that the region is still active to the present time. A seismic array in the south peninsula and a number of local networks have detected considerable seismic activity in the shield region. Clusters of epicentres are seen along the faults present in the region.

The epicentral maps are used for preparing seismic hazard map. Seismic zoning map is in the code for designing earthquake resistant structures. Apart from the earthquake data, geological factors, structural design, soil data etc., are used for preparing the building codes. These codes are used for designing earthquake resistant structures in the region. Upgradation of this code is a continuous process. The building code is reviewed from time to time. The different zones indicate vulnerability from seismic disturbances and help in assessing the hazard potential.

However, in order to assess the exact nature of risk, several other important factors such as gravity, magnetic, geodetic, electrical data are necessary. These data are then used to prepare microzonation maps which are used for urban and rural planning.

Landslide

Landslide zonation map comprises a map demarcating the stretches or areas of varying degrees of anticipated slope stability or instability. The map has an inbuilt element of forecasting and is hence of probabilistic nature. Depending upon the methodology adopted and the comprehensiveness of the input data used, a landslide hazard zonation map able to provide help concerning some or all the following aspects:

Location
Extent of the slope area likely to be affected, and
Rate of mass movement of the slope mass.

One of the early projects on zonation was carried out by Central Road Research Institute in 1984, in which hazard zonation techniques were used to choose a most suitable alignment from the possible alternative alignments on landslide affected stretches in Sikkim area. Subsequent monitoring has shown that the choices made have been proved to be successful. During 1989, a hazard zonation map was prepared for a part of Kathgodam-Nainital highway. This map was prepared with the objective of enabling the department to evolve a suitable maintenance strategy to keep the hieeslopes along the road free of landslide problem.

Preparation of a comprehensive landslide hazard zonation map requires intensive and sustained efforts. The problem is highly interdisciplinary in nature. A large amount of data concerning many variables, covering large slope areas has to be collected, stored, sorted and evaluated. Finally, the degree of risk sliding has to be evaluated and zonation maps prepared. The use of aerial photographs and adoption of remote sensing techniques helps in the collection of data. For storage, retrieval and analysis, adoption of computerized techniques would be useful.

Hazard zonation maps have multifarious uses, some of which are listed below:

In the preparation of development plans for townships, dams, roads, and other development
General purpose Master Plans and Land use Plans.
Discouraging new development in hazard prone areas.
Choice of optimum activity pattern based on risk zones.
Quick decision making in rescue and relief operations.

Clearly such maps have a large number of users, including several Government Department, and private agencies as well as NGOs involved in any type of development, construction of disaster management work.

Search and Rescue (SAR)

Search, rescue and evacuation processes are carried out immediately after the disaster has struck a certain area or zone. These are the most important operations which are usually performed by the local volunteers, voluntary organisations and the district and state agencies. If the condition worsens and these groups are not able to control the situation, then the army has to be called in.

The basic aim of all such operations is to ensure the survival of the maximum possible number of victims. A plan is worked out with the help o local people and through aerial surveys and then appropriate steps are taken by the various teams involved, to carry out the operations. Besides bringing about material relief, the aim is also to control panic and confusion, and to provide moral support.

Importance of Significance of SAR Search and rescue, often known by the acronym SAR, is the process of identifying the location of disaster victims who may be trapped or isolated, and bringing them to safety and providing them with medical attention.

Search and rescue generally involves the local people who are well versed with the local terrain and can be instrumental is searching and accessing the trapped vtims. SAR teams also depend on sniffer dogs and heavy machines such as cranes and earthmovers etc., to search out and extricate the victims from difficult situations such as collapsed buildings.

In case of floods and cyclones, boats and helicopters are used to carry out the search and rescue operations by forming different teams and carrying out SAR operations in the entire area systematically, each team covering its assigned sectors.

After the search, rescue and evacuation, some important steps are required to be taken in order to provide relief to the evacuees.

Prime amongst these are:

Shelter
Food
Communications
Clearance and access
Water and power supplies
Temporary subsistence supplies
Health and sanitation
Public information
Security
Construction requirements

Methods and Techniques

Traditionally, due to lack of technology and scientific approach, it was difficult to carry out the search, rescue and evacuation operations. The only possible way for the teams was to work with the help of local people who volunteered themselves during such operations. The teams used to move around in vehicles/boats/helicopters to search out people and rescue them.

In the present context, due to scientific advances it has become easier to carry out these operations efficiently. Studies have helped in making it possible to forecast and simulate disaster occurrences with specific locations - helping in the initial stages of search and rescue operations. There are techniques available, like remote sensing through satellite imagery and GIS, which help to identify areas that are disaster prone, zoning them according to risk magnitudes, inventory populations and assets at risk, and simulating damage scenarios. These tools are useful even in managing disasters as they provide instant access to information required for management decisions. Modern communication systems have also proved very useful, particularly in search and rescue operations. They not only help in providing waring before the disaster, but also help in creating awareness which helps in reducing panic, confucion and mental stress. A communication netowkr system helps in establishing contacts between relief teams, which with better centrral coordination can work more efficiently and be more effective. It is for this reason that various control rooms are established to manage the disasters, and in case of cases such as floods and cyclones, which can be predicated in advance, such control rooms also set up in advance.

Conclusions

The scale and intensity of natural disasters in the country makes it imperative that a comprehensive approach may be adopted in managing them at the country wide level. One of the first steps in this direction would be to establish a common and uniform database at the national level. Needless to mention, the common database should be made available to all concerned agencies in the government as welll as the non goernment sector. Among the availabel technologies, GIS presents itself as the most useful tool in making it possible. Indeed the scope of GIS is much beyond Disaster Mapping and SAR. Bringing in GIS applications in mainstream Disaster Management process should therefore be accorded top priority.

Reference:

Natural Disaster Reduction, South Asian Regional Report (Proceedings of the SAARC Workshop on natural Disaster Reduction), March,1994
Cyclone Contingency Plan of Action, Revenue Department, Govt. of Andhra Pradesh, Hyderabad,1987.
Carter, W. N. (1992) Disaster Management: A Disaster Manager's Handbook Asian Development Bank Manila
Institute of Civil Engineers for Overseas Development Authority: (1995) Megacities: reducing vulnerability to natural disasters. Thomas Telford London.