Drivers of vulnerability to wetlands in Punarbhaba river basin of India-Bangladesh

Abstract

Wetland degradation and loss of wetland is one of the emerging challenges against sustaining such worthy environmental capital having plenty of goods and services. In Barind tract of India and Bangladesh, such trend of wetland conversion is highly explicit. Present paper attempted to capture such trend of wetland loss, conversion of wetland and their associated reasons behind. At present total wetlands area of the basin is 220.9 km2 and which is 35.78% lower than pre-dam wetland coverage. Flow modification triggered by Komardanga dam (34.35% for average flow and 52.24% for peak stream flow have declined) is emerged as one the major reasons behind wetlands loss. It also causes reduction of active flood prone area by 39.72% as well as inconsistent water service to wetlands. De-linking of Punarbhaba river system from Tista river system is another historical cause behind lowering of flow and flood magnitude in Punarbhaba. Loss of tie channels is also responsible for irregular water service to the wetlands. In last 30 years, about 100 km2 of wetland is transformed into agricultural land, which points out the responsibility of agricultural extension for wetland deterioration. So, periodic monitoring of wetlands, release of ecological flow and stop agricultural encroachment are necessary for sustaining wetland.