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Forest fire risk area mapping of GIR - P. A. Integrating Remote Sensing, meteriological and topograpgical data - A GIS approach


K.L.N. Sastry
klnsastry@hotmail.com

Ravi Jadhav and P.S. Thakker
Forestry and Environment Division (FED), FLPG/RESA
Space Applications Centre (ISRO),Ahmedabad

Introduction
Regulated or controlled fire is a very useful and legitimate tool in forestry practices for accomplishment of specific purposes. For instance, natural regeneration of teak (Tectona grandis Linn.f.), sal (Shorea robusta Gaertn.f.) and deodar (Cedrus deodara (D.Don) G.Don f.) is intimately associated with the role of controlled fires, NCA (1976). However, uncontrolled fire, whether natural or manmade, can cause havoc, that too, in a short span of time. It is the greatest enemy of the standing vegetation. The total damage from the forest fires is very large. Wild animals are killed. Small trees and regeneration are often affected very adversely. Even the big trees are not spared if the fire is severe. Ground fire destroys the organic matter which is very necessary to maintain an optimum level of humus in the soil. Repeated annual fires may decrease the growth of the grasses, herbs and shrubs which may result in increased soil erosion. A study made by the Forest Survey of India reveals that 51% of the forest area in Assam and Gujarat, 93% in Arunachal Pradesh, 67% in Bihar, 69% in H. P., 46% in J & K,45% in Karnataka, 76% in M. P., 94% in Meghalaya and Orissa, 87% in Nagaland, 58% in U. P. and 33% in West Bengal is subject to repeated annual fires, Lal (1989).

Fire and grazing have resulted in eliminating tender species, and making hardy species more abundant. Bamboo has been almost wiped out from many parts of central India, on account of its being extremely sensitive to damage from fire.

Literature is implete with the studies that report on the extent of fire or the damage caused by the fire. Nichols (1987) has attempted to develop a Forest-fire Add System Technology (FAST) for operational use in detection and mapping of forest-fires. It was envisaged to provide in near-real time, the forest-fire information to fire management at the incident command post. Khan et. al. (1989) have used multi-date Landsat data for determination of areal extent of fire affected areas in parts of Betul and Hoshangabad Districts of (MP). Khan et. al. (1992) mapped the fire affected areas in Bandhogarh National Park (MP) using IRS LISS-II data. Ayanger (1992) has carried out mapping and monitoring of forest-fire in parts of Thane and Gadchivoli districts of Maharashtra through satellite remote sensing. However, all these studies/reportings are the assessment of the aftermath. None of them were suggestive of any measures that could have averted the disaster.

While it is not possible to asses the actual damage caused, according to the figures available in the Forest Survey of India report (1987), fire occurred as many as 17,852 times in the country bringing an area of 5,72,417 sq. km. under fire and causing loss/damage over 7 million rupees during the VI Five year plan. To avert these most disastrous and damaging incidents, preparation of the forest - prone area map is a first step. In the present study, an attempt has been made to prepare this map integrating the satellite and the topographical data through Geographic Information System.

Gir forest located in the Saurashtra Peninsula of Gujarat is the largest biologically intact continuos tract of forest and the only abode of the Asiatic Lion in the world. It is situated between 20o 40’ N to 21o 50’N and 70o 50’E to 71o 15’E longitude respectively. The total area of the forest is 1882.6 sq. kms out of which 1412.12 sq. kms has been constituted as GIR Sanctuary and National Park (PA). It supports a rich biodiversity comprising of about 450 recorded flowering plant species, 32 species of Memmals, 26 species of reptiles, about 300 species of birds and more than 2000 species of insects. (Singh 1996). The forest is rugged and hilly with elevation varying from 150.3 to 530.7 mtrs. above sea level. The area is draining by 7 rivers which originate and pass through the forest. The area has an annual rainfall of about 980 mm and mean monthly temperature vary from maximum of 44o C to a minimum of 10o C.

Importance Geographical Information System (GIS) in Fire Risk Area Mapping
The most important use of GIS is its ‘modeling capability’ i.e. constructing models of the real world from digital database. Simulating the effect of a specific process over time for a given scenario. Modeling is a powerful tool for anal; trends and identifying factors that affects them, or for displaying the possible consequences of planning decisions or projects that affects them, or for displaying the possible consequences of planning decisions or projects that affect resource use and management (FAO. 1988). Forest management can draw benefit a lot from such a capability for decision support systems.

Remotely sensed data particularly from the satellites, is in a ready-made spatial-data format for GIS. Thus it is playing a very important role in the utilization of GIS technology. On the other hand GIS technology is helping in overcoming classification errors of remotely sensed data due to “infinite number of combination of materials, angles, illumination, reflectance, emittance, temperature and other physico-chemical-biological parameters” by allowing satellite data on the same area such as elevation, soil, climate, etc. “Remote Sensing data, thus bears a synergistic relationship to GIS technology and undoubtedly will be a major source of both original and monitoring information on the earth’s environments in the future” (Parker, 1990).

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