Environmental Impact of Conversion of Natural Wetland into Reservoir: A Case Study of Chotiari Reservoir in Pakistan

Freshwater natural wetlands are under threat of environmental degradation due to the anthropogenic and natural activities. In some cases, wetlands are transformed into manmade water reservoirs which have resulted in waterlogged and salinity problems in the nearby areas. Conversion of Chotiari natural wetland into the off canal manmade Chotiari Reservoir is a typical example of unsustainable irrigation project in Pakistan. A study was conducted to quantify the impact of construction of a reservoir on the vegetation and waterlogging in the adjacent areas of the reservoir using remote sensing and geospatial tools. The analysis of satellite imagery of the 5 km buffer around the periphery of the reservoir revealed that before the conversion of the lake into the reservoir about 2594 ha (4.6% of the buffer area) was waterlogged which increased to 6850 ha (12.1%) in the year 2017. The salt-affected area was 4786 ha (8.5%) which increased to 7364 ha (13%) in the year 2017. Thus, about 2578 ha (4.5%) of the fertile agricultural land changed into unproductive salt-affected soil. About 9% of natural vegetation within lake boundaries decreased due to conversion of natural wetland into the reservoir and resulted in degradation of lake and environmental disaster.