Classification strategies for forest cover mapping of hilly terrain in eastern Himalayas, Sikkim a case study
S. Sudhakar and S. Sengupta
Regional Remote Sensing service centre, dept. of space,
IIT campus, Kharagpur - 721 302 India
M.L. Arrawatia
State forest department, forest secretariat,
Gangtok, Sikkim
Abstract
The State of Sikkim, a part of Eastern Himalaya has immese forest resource potential which has not been documented in recent times due to number of constraints.
The application of remote sensing techniques for plain/undulating terrain conditions is always easy to understand and it is possible to acquire utmost accuracy. However, the hill terrain conditions are not conducive to achieve considerable classification accuracy in view of various factors including shadow.
In the present investigation, the problem expected and their solutions have been dealt with in detail by generating a case study pertaining o Chungthang area of North District of Sikkim. The change of vegetation types as altitude changes has also been studied by applying indigenously developed Digital Terrain Model on the raw and classified data.
1. Introduction
Forests, the source of renewable energy has been over-exploited due to various pressures despite the recognition of their role for ecological stability and balance. As per the statistical data, the forest resources are dangling at a faster rate than the regeneration by afforestation schemes. In Asian itself, the rate of deforestation is 1.8 m. ha as against the afforestation of only about 0.4 m.ha (Rao 1990). The National Forest policy proposes that the total area under forests in the country be increased steadily to cover at least one-third of the total land area, the proportion aimed at being 560 per cent in hilly area and 20 per cent in the plains.
The satellite remote sensing technology with its synoptic view, repetitive coverage and less cost for generating reliable, upto-date information with more than 90 per cent accuracy, paved the way for frequent utilization of this technology for forest cover mapping in various parts of the world including India ( Madhavan Unni 1990).
The State of Sikkim, a part of the Eastern Himalaya has immense forest resource potential. The existing forest stock has not been properly documented in recent times in view of impending difficulties due to hilly terrain conditions. The State Forest Department of Sikkim in association with RRSSC, Kharagpur, has taken up forest cover mapping of the entire Sikkim using IRS-1A LISS-II data pertaining to Nov. 1988. A part of the scene covering 18x18 sq. km. around Chungthang (Lat. 270 - 40' N and Long. 880 - 35' to 880-45' E ) North District, Sikkim has been taken up as a case study to formulate classification strategies for forest cover mapping. The present discussion highlight the methodology adapted for the classification of forest cover of Sikkim using different strategies to achieve better accuracy. (Location Map. 1).
