Impacts of Embankment System on Natural Wetlands and Sustainable Water Resources Development in the Northwest Region of Bangladesh

In the Northwest region of Bangladesh, the Chalan Beel is one of the largest Beel ("Beel" refers to natural wetland) in Bangladesh. Polder C (an area surrounded by embankment) of Chalan Beel area consists of 50% natural wetland of the region. Historically, the area was rich with fish, flora and fauna, and agricultural resources. Both flood and drainage congestion have been identified as major problems existing in the project area. Farmers are badly affected by the sudden onrush of floodwater through the embankment breaches, public cuts and incomplete hydraulic structures during the rainy season. The floodwater damages B. Aman and late Boro paddy by 10% and washes away housing settlements. Sometimes water gets scarce in polder C in dry season that is unfavorable for the crop. Loss of crops and fishery affects the economy strongly. The polder was not according to master plan and with lack of operation and maintenance. Instead of improving the livelihood in the study area the embankment arises detrimental effect on the people. This paper focuses mainly the impact of the embankments on hydrology, fishery, agriculture and socio-economic condition in polder C at Chalan Beel area. Present conditions are compared with the natural conditions existed in the last decades. Finally, the paper gives some recommendations for further sustainable water resources management. It is estimated that the natural wetland loss is about 10%. The analysis shows that the river or channel cross-sections are reduced by ca. 2 m and water level is increasing with time in the rivers along the polder due to confinement effect and siltation. It appears from the study that due to this confinement effect and siltation effect, flood and drainage problems are increasing and consequently, the area is affected in every year to a great extent. At present, cross sections of natural canals are not working properly and back water flow from Hurasagar River creates drainage congestion. About 20% of fish production has been decreased over time and some species such as Gongsha, Khailsha, Chandina etc., are in threatened condition. Though agricultural production has been increased after construction of the Polder C, wetland status on the basis of wildlife and natural vegetation has been decreased significantly. This study clearly indicates that water resources infrastructure development should consider a wide range of components of integrated water resources management (IWRM). Non-sustainable planning and management of infrastructure may lead to economic benefit but causes harm to the natural ecosystem. Based on the study out come the following suggestions have been derived: (1) Integrated water resources management plan should be prepared based on the conjunctive use of surface water and ground water, (2) in some potential places low height dam may be constructed to store water for Aman crop in monsoon season, (3) proper training and credit support are needed for project beneficiaries for fishery, agriculture and others sectors in the polder, (4) The polder C was implemented using top down approach giving less importance to the beneficiaries but for the sustainability of the projects, stakeholders opinion should be in consideration which is termed as bottom up approach.