EFFECT OF MAN-MADE STRUCTURES ON NATURAL WETLANDS IN PAKISTAN: A CASE STUDY OF CHOTIARI RESERVOIR

Abstract

Chotiari was a natural wetland before the construction of the reservoir. In 1994 wetland was converted into a reservoir to develop a water source for the people. But due to lack of proper attention this reservoir promoted waterlogging and salinity problems instead. The goal of this study is to investigate the variation that occurred on the land cover of the Chotiari wetland and surrounding area, before and after the construction of the reservoir. Satellite images of Chotiari reservoir and its buffer up to 5 km area of 1990 and 2019 were taken. The study was conducted at USPCASW (United States Pakistan Center for Advanced Studies in Water) Mehran University of Engineering and Technology Jamshoro. In the study, compositing was done by GIS (Geographical Information Systems) to join the bands of images of 1990 and 2019 for observing changes. After extracting the required shapefile of the Chotiari reservoir and its buffer, unsupervised classification was done for three classes: water, vegetation, and barren land. The difference in areas of water, vegetation, and barren land was calculated by superimposing both the images and joining all the bands of Landsat 5 image and Landsat 9 image. By comparing results of both years, a 12% increase in water availability was found whereas 8% and 4% net reduction was found in both vegetation and barren land, respectively. The main reason behind the increment of water quantity might be the construction of a reservoir. Moreover, it also affected the 5 km buffer area around the reservoir which resulted in a 9% reduction in water, 11% increment in vegetation, and 2% drop in the barren land.