Sustainable river works – Gorai River

Planning and design

The design was to create a low-water channel from the bifurcation to some 30 km further downstream. This channel would cover only part of the cross-section and restore the river’s natural cross-sectional shape. Due to the widely varying discharges, however, the morphological response to this intervention was rather uncertain. Detailed planning made little sense and adjustments to the actual morphological development has to be possible during construction. 

During the wet Monsoon season, some parts of the dredged channel would fill in. Therefore, dredging continued over three successive years in the wet season, expecting the river to be able to maintain itself afterwards. In the end the river should have become a self-sustaining ecosystem, combined with limited maintenance dredging to keep the bifurcation open.

The principal driver of the project was to conserve existing environmental values and to create new ones by restoring the river discharge and reducing salinity intrusion into the Sundarbans area. Moreover, the increasing flow would positively influence the water quality of the river and the connected surface waters, indirectly impacting the level of well-being (nutrition, poverty alleviation, employment) of the Bangladesh people.