Amit K. Bhattacharya and P. K. Srivastava
Department of Geology and Geophysics
Indian Institute of Technology Kharagpur
Kharagpur – 721 302, West Bengal, India
Email: [email protected]
Coastal zones are constantly undergoing wide ranging changes in shape and environment due to natural as well as human development activities. Natural processes such as waves, erosion, changes in river courses etc., cause long time effect at slower rate; but man made activities, such as settlement, industrial activities, recreational activities, waste disposal etc., affect the coastal environment at comparatively much faster rate. Most of marine finfish and shellfish depend on these coastal habitats for their survival. Continued loss of these wetlands may lead to the collapse of coastal ecosystems. It is, therefore, necessary to monitor coastal zone changes with time. The present paper is intended to monitor changes in wetland habitats and adjacent uplands in eastern coastal zone of India at intervals of five to ten year cycles. This type of information and frequency of detection are required to improve scientific understanding of the linkages of coastal and submerged wetland habitats with adjacent uplands and with the distribution, abundance and health of living marine resources. Satellite imagery (primarily IRS – P3 WiFS and IRS – 1B LISS II), aerial photography, and field data are interpreted, classified, analyzed, and integrated with other digital data in a geographic information system (GIS). The resulting land cover change databases are disseminated in digital form which can be used for conducting geographic analysis in the study area in future.
The present work deals with the study of a part of the eastern coastal zone of India, occurring between Subernarekha river mouth in the north and Rishikulya river mouth in the south using remote sensing sensor data. The shoreline within this area is approximately 500 km long and lies between latitude 18 0 0′ to 21 0 30′ N and longitude 84 0 45′ to 87 0 30′ E. Initially IRS – P3 WiFS data (path/row – 101/62) has been digitally processed using various image processing techniques, to monitor coastal land cover changes of the study area. However, detail land form changes have been carried out using high resolution IRS – 1B LISS II satellite sensor data along with aerial photographs corroborated with selective field studies. Finally, the existing landuse/landcover map of the study area has been drawn. This analysed result is compared with historic base maps acquired from Survey of India topographic sheets of the period 1970-80.
The Coastal Land cover has been subdivided in to three super classes namely, 1) Upland landcover, 2) Wetland, and 3) Water and Submerged Land. These super classes are subdivided into class which are further subdivided into subclasses. The classification system focuses on landcover classes that can be discriminated primarily from satellite remote sensor data. The Uplands super class consists of five classes, viz, developed land, cultivated land, grassland, woody land, and bare land. Wetland super class consists of six classes, namely, marine/estuarine rocky shore, marine/estuarine unconsolidated shore (beach, flat, bar), estuarine emergent wetland, estuarine woody wetland, riverine unconsolidated shore (beach, flat, bar) and lacustrine unconsolidated shore (beach, flat, bar). Water and Submerged Land consists of those wetlands with surface water but lacking trees and shrubs.
This study shows that IRS – P3 WiFS and IRS-1B LISS II data can be successfully used in studying the coastal landuse/landcover and landform of the eastern coast of India. These themes were integrated in GIS and change detection analysis have been carried out using algorithms developed in GIS environment.