Padma Multipurpose Bridge Project

temporary drainage problem in those areas. A significant part of the dredge material will still requiremanagement. Land disposal for the rest amount of dredge material in Janjira side will entail landreclamation; a preliminary estimate indicates a land requirement of 1,133ha with a 3m height aboveexisting ground level for the dredge material management. Such large land reclamation is likely toresult in significant drainage problem in the filled area. Dredge material management by landreclamation at Mawa side will result in similar drainage problem but to a lesser extent in an area of50ha only.54. Vegetation and Crops: RTW right-of-way requires strip of 100m in Mawa side and 300m in Janjiraside, which will require about 328 ha agricultural land. In addition, dredge material management byland reclamation will require total destruction of existing vegetation over the lands used for thepurpose, which may include clearing of trees, bushes, grasses. Table 7-10 provides the cropproduction loss in both sides of the RTW alignment. It is estimated that cross production loss will be387.06 tons in Mawa side and 12,931 tons in Janjira side.Table 7-10: Crop production loss in the RTW right-of-wayCrop Production (ton)Crop Type Mawa JanjiraRice 193.53 840.38Potato 193.53 0Mustard 933.75Wheat 1139.18Jute 1089.38Onion 3112.51Garlic 2334.38Coriander 479.64Cumin seeds 54.64Sugarcane 2490.01Banana 456.80Total 387.06 12,930.67Source: Consultant’s Estimate, 200955. Aquatic Habitats: The dredging operation for the preparation of RTW slope will temporarily disturbriver ecology during construction and permanently acquire floodplain land. Both impacts are highlysignificant in view of the large footprint of the RTW, which is estimated at 328 ha on land (floodplains)and 292 ha in underwater (river). Impacts on the Seasonal Wetland. The main impact in the floodplain will be a decline of seasonalwetlands, which are the agricultural lands inundated during the monsoon periods. Their ecologicalsignificance is more or less comparable to that of the submerged areas around the habitatedCharland; acquisition of these seasonal wetlands will result in a loss of feeding and nursing biotopeof all fish and crustacean species. Based on the updated RAP III data, it is estimated that RTWconstruction will require about 328ha of seasonal wetlands (agricultural land), which will be apermanent loss of floodplain feeding and nursing ground. Impacts on River Ecology: Lower (underwater) slope erosion protection placed on a dredgedslope with the toe of the slope set at various elevations depending on the location and crosssection type. Rock riprap placed on a geotextile/bamboo fascine mattress is used to provide theerosion protection. A falling apron placed along the toe of the underwater slope protection, toprovide temporary protection from future undermining by boat-launching down the scoured slope.Rock riprap will be used for the falling apron. The slope protection work will have temporary impacton river ecology during construction. It will occupy about 295ha of important feeding and breedinghabitats for virtually all aquatic fauna in the submerged parts of the embankment during three yearconstruction that will be replaced by a smooth sloping revetment bund consisting of dredge materialcovered with artificial material. Protected stable riverbanks with underwater slope coverage havethe potential positive impact of providing more shelter to fish and other aquatic life compared withpresent embankments. There are no direct mitigation measures possible for the temporarydisturbance of habitat, but the impacts support the need for compensation in the form of fishreserves or sanctuaries in the riverine zone in up and down stream areas.7-18