Monitoring of geomorphological changes for planning reclamation work in coastal area of Karachi, Pakistan

Abstract

The coastal zones form an important segment and play a vital role in the economy of the country. The land–water interface comprising of coastal zone is modified all the time by oceanic currents, waves and tidal oscillations. The sediments are brought into the creeks from the erosion prone open coast beaches as well as through small rivers and inlets, and dispersed and deposited along the coast. Satellite Remote Sensing (SRS) due to its repetitive, multi-spectral and synoptic nature provides a unique view to recognize various features on land and sea. SRS techniques can be of great help in collection of continuous wave currents, wind, tides, suspended matter, shallow water area, wetlands, mangroves, mudflats and other coastal features and coastal changes, like land accretion or erosion. Therefore, a study has been undertaken to monitor geomorphological changes along the coast of Karachi using multi-temporal Landsat MSS and TM data from 1978 to 1998. SRS data were processed using interactive digital image processing/enhancement techniques like colour enhancement, Principal Component Analysis (PCA) and by Colour draping techniques and different enhanced products of the area have been prepared. The multi-temporal PC analysis results were integrated with each other and with navigational map of the area by GIS technique. The geomorphological changes occurring at the middle part of the coast of Karachi along Bundal and Buddo Islands and in Korangi–Phitti Creek area were delineated. The integrated techniques applied on multi-temporal SRS data in this study were found very useful for monitoring and mapping the land accretion and erosion processes. The analyses provided the old as well as the most recent data base of coastal environmental conditions of the study area, which may led for better understanding of coastal processes and help for planning reclamation work in this area.