CLASSIFICATION OF FOREST TYPES OF DEHRADUN REGION FROM MULTITEMPORAL SATELLITE DATA

Abstract

Forests are one of the most important renewable resources of inestimable value to the people. Forests protect and preserve the physical- features, prevent floods and check the flow of subsoil water and thus help in maintaining the productivity of the cultivated land. During the last three decades, India has been continuously losing forest resources mainly due to exponential population growth, higher living standards, industrialisation and other related developmental activities. In order to take effective steps for conservation of the same, it is essential to have an updated data pertaining to different types of forest availability in that area. Monitoring of the area is possible, by using a suitable technique which can assess past & present conditions of forest and vegetation types and produce quantitative data for the same. Remote sensing data products reportedly, have been used effectively for the classification of different forest and vegetation types, due to several unique characteristics, such as synoptic view, repetitive coverage and uniformity of data. The present study was carried out in Dehradun & surroundings (= 1700 sq.km.) to classify available forests and vegetation types and monitoring the changes in terms of afforestation & deforestation, using satellite data of different dates such as, FCCs of 1972, 1977, 1982 & 1994 and digital data of 1991. LANDSAT MSS FCC data of years 1972,1977 & 1982 were available at 1:250,000 scale and IRS LISS II data of year 1994 was available at 1:50,000 scale. At 1:250,000 scale, various forest & non-forest classes such as Sal forest, Mixed forest, Chir forest, Rani forest, Plantation, Agricultural area, Grass/Scrub, Habitation and Waterbodies were identified in the area by employing visual interpretation technique while the additional classes identified from FCC at 1:50,000 scale include, Cultivation with Habitation, Khair, Sisoo, as well as the forest cover of above & below 40% crown density. Areal extent of various -elassaa listed above were computed from multidate satellite data and these were compared to assess the changes as well as afforestation & deforestation areas. For example, on comparing the results of 1982 and 1992 it was found that Sal forests have decreased by 115 sq. kms and plantation and habitation have increased from 9.99 to 11.82 sq.km., and 6.25 sq.km. to 15 sq. km. respectively. These changes indicate afforestations and deforestations in the area. Results of visual interpretation analysis were compared with the maps prepared by Forest Survey of India, Dehradun and Remote Sensing Application Centre, Lucknow and it was found that the difference in areas is very small. Digital data products, though expensive, are much faster in processing, particularly if multitemporal data are to be analysed for mapping & monitoring of forest & vegetation classes.