Padma Multipurpose Bridge Project

2. The Project influence area will broadly cover (a) 6km north of Riverbank in Mawa side, 4kmsouth of Riverbank of Janjira side, 15km upstream (west), and 7km downstream (east), (b) the corridorof the Asian Highway 1 (Tamabil-Sylhet-Sorail-Kanchpur-Dhaka-Mawa-Bhatiapara-Norail-Jessore-Benapole), and (c) the corridor of Trans-Asian railway network and the railway missing link fromGendaria-Mawa through the bridge to Bhanga-Kashiani-Narail-Jessore-Benapole. The influence areain north and south is determined to cover the area of the Project direct components (service areas andlanding of transition structures). The farthest component service area in Mawa side is located 4kmfrom the Riverbank and in Janjira side the approach road is about 3km from the River bank. We added1 km additional in each side to this boundary to define the project influence area. The backwater effectbased on hydrological modeling outcome is minimal (10cm) at a water surface slope of 0.000045,which translates into an upstream distance of 1.5km. And the influence area in east-west (along theRiver) has been revised from the initial coverage of 15km by 12km to 15km by 7km. The influencearea 15km in upstream (west) to cover the distances of RTW and approach road (which is about adistance of about 13km from bridge landing site), additional 2km is considered to cover the wholeChar Janajat. On the other hand, the influence area in downstream has been revised from 12km to7km to cover the downstream Char Majirkandi (because RTW coverage in downstream has beenreduced significantly for the preferred alternative). This Charland (newly emerged Charland withouthabitation and vegetation) is considered in the EIA as a potential location of temporary dredgedmaterial disposal during the dry season.Figure 2-2: Probable erosion vulnerable areas due to structural interventions3. In addition, based on the morphological study for structural intervention (Updated RTW SchemeDesign, Annex C, Section 9.4, submitted on April 15, 2010), it is identified that for different types ofchannel development due to the construction of river training works, three locations (Figure 2-2) couldbe vulnerable to erosion and the extent and magnitude are considered indicative. There is noconfirmed analysis on these erosion predictions. Compare is not the boundaries based on naturalenvelope for the next 50 years and the maximum erosion extent for the structural interventions showsthat additional erosion for the structural interventions would be about 900 ha along the right bank,located at about 15 km downstream of the bridge crossing. Since, these changes are not immediate, amonitoring program for the downstream river (for example as part of the regular annual monitoring2-3