Evaluation of environmental impacts of Gorai river dredging

Abstract

One of the major activities of Gorai River Restoration Project-II was dredging the river for a reach of 30 km. The main objective of this research was to analyze the impacts the project on salinity, surface and ground water level, irrigation, crop productivity, fish productivity, navigation, cost of river transport and rural employment. Long- and short-term impacts of the project were assessed. In order to achieve this goal, questionnaire survey was conducted in Kushtia district. About 350 respondents were selected from three upazillas (Kushtia, Kumarkhali and Khoksha) using a simple random sampling technique. A conceptual framework was developed, and data were analyzed using evaluation values of Important Environmental Components (IECs) and prepare impact matrix. This study found that, 99% of respondents replied that there is no salinity in Gorai River after dredging. As per questionnaire survey, availability of surface water during dry season has increased as stated by respondents (86%). Average water level in Gorai River of Phase-II is 4.48 m which is more than the average water level (4.36 m) of Phase-III. So, the availability of surface water in Gorai River is increased. Availability of water in the tube well in dry season has increased as stated by respondents (91%).

The quality of irrigation water is very much dependent on the source. It was also found that, during dredging about 2% of respondents use water using Low Lift Pumps (LLP) from Gorai River but after dredging about 15% of respondents use water through LLP from Gorai River. On the other hand, dependency of irrigation water from other sources is reduced from 82% to 70%. From questionnaire survey, farmers adjoining the Gorai River were observed to be converted from 1 crop to 2 or more crops production per year. In 2021, 93.0% of the farmers have stated that volume of production of crops increased (compared to 91% in 2013). In 2021, 52% of the fisherman stated that the volume of fish production increased (compared to 30% in 2013). During dredging about 88% (2013) of Boatman reported reduced flow in Gorai River during dry season but after dredging about 68% (2021) of Boatman reported the same. Compared to 22% in 2013, 32.0% (2021) of the boatman felt that navigability during dry season increased slightly due to dredging.

However, the water flow in Gorai River depends not only on dredging but also rain and extent of water flow from India during dry season. Rural employment scenario changed after dredging. In 2021,Rural employment of Farmer 57% (43% in 2013), Fisherman 52% (50% in 2013) and Boatman 36% (34% in 2013) has increased in the project area.