Padma Multipurpose Bridge Project

interrelated. The Padma-Meghna, through which the combined discharge of the Ganges,Brahmaputra and Meghna flows into the Bay of Bengal, is the major river of this part of the delta. ThePadma is 1.6 to 8.0 km wide and despite having broad meanders shows a braided character. Allthese make the Padma a unique habitat for fish regeneration.3.2.4.3 Limnology72. In general terms, the Padma River water is alkaline with a pH above 8 and a conductivity of160-410μs (Table 3-21). The alkaline pH reflects underlying soluble cancerous rocks in parts of thecatchment area. The conductivity, which increases along the length, is relatively high. Temperatureshows considerable variation along downstream of the river and is probably a major environmentalfactor influencing the distribution and nature of fish communities. High seasonal variation intemperature is observed in the river.Table 3-21: Hydrological data for experimental site (Mawa) along the PadmaSite Altitude (m amsl) Water temperature ( 0 c) pH ConductivityMawa 22 19.4 8.46 309.0Source: FAO3.2.4.4 Fish Habitat Description73. Fish habitat of the area is classified by main river channels, canal and connected seasonalwet lands (Table 3-22). River channels water quality is good for fish habitation. Average depth of riveris 20-21 meter, Canals 3-4 meter, and wet land 1-2 meter, respectively. Siltation rate of river variesfrom 1-2 inch per year. The buffered fish habitat area around the bridge construction site is given inFigure 3-32 of which, 87% is occupied by river channels. Wetlands and canals are playing major rolein sustaining the fish production.Table 3-22: Fish habitat area of the buffered study area (5 km circle)Habitat nameHabitat area(in ha)River channel 1000Wetland 86Canal 70Wetland7%Canal6%River87%Figure 3-32: Fish habitat classification of the study area3.2.4.5 Fish Production74. The river Padma is characterized by large floodplain and interaction with the estuarine zone.The largest single component of the inland fisheries in general is Hilsa, which migrates up river fromthe Bay of Bengal to spawn. In the Ganges (Padma) section of the delta in Bangladesh by far themost dominant species of the catch is Hilsa (FAP 17 1995), which can be 45-47 percent of the catchalthough this shows considerable annual variation. Of this riverine total in Bangladesh, the Padmacontributes around 4-5 percent. However, result of the fish catch assessment survey showedsignificant variation in fish catch effort among different fishing gears. Gulti jal showed highest catchper unit effort (CPUE) 3.9 kg/hr followed by Ber jal, Chandi jal, Sutar jal, Bana basail and Doair chai.3-46