Padma Multipurpose Bridge Project

Criterion Alternative 1Revetment along bankriver morphology and any long-termimpact would be masked by naturalchanges depending on the annuallychanging flood characteristics.Alternative 2Guide bund & hard points onbankAlternative 2 modifiedGuide bund on bank, hard points oncharConstruction impacts with longer termconsequence(Change in land-use and loss of habitatas a consequence of filling floodplainareas used for construction works aboveflood levels)Same for all alternativesSame for all alternativesIt is estimated that while in about halfthe cases the fertile topsoil can bestockpiled and placed over the fill afterconstruction ends; it will not be practicalfor the rest of the areas, especiallythose used for construction yards andleased on an ad-hoc basis. Here the fillremains as infertile sand resulting fromdredge spoil, which does not encouragere-growth of the original habitat.Same for all alternativesLong term impact on floodplain ecology(Long term impacts on the floodplainhabitat arising from the completed workdespite mitigation measures)Long term impact on river ecology(Long term impacts on the river habitatarising from the completed work despitemitigation measures)190 ha of flood plain land will be lost forRTW.Minimal Impact since the existing southchannel will remain undisturbed andonly experience slightly attracted flowdue to riverbank protection120 ha of floodplain land used forRTW.Further, It is expected that about510 ha of floodplain land will belost due to future erosionbetween two hard points.Moderate Impact since theexisting south channel will remainundisturbed however, withlocalized more turbulent riverenvironment at hard points.52 ha floodplain land and 197 hachar land lost for RTW.About 880 ha new land will bedeveloped due to filling of southchannel. However, there is potentialloss of 760 ha of Charland due tofuture erosion.South channel river ecology will bedestroyed due to filling of southchannel. A new channel will beformed on char and create turbulentflow around hard pointsLong term impact on floodplain hydrology(The RTW can change the flood plainflows for example through theconstruction of closed embankmentsNo impact since distributaries that carryfloodwater to the flood plains across theapproach road confirmed in position.However, there will be some impact inImpact on distributaries throughhigh “hard points” connected toapproach road and some impactin area of bridge due toHigher impact on distributaries thanAlternative 2 with chance oftemporary closure of distributariesand some impact in area of bridge6-27