Poldering vs compartmentalization: The choice of flood control techniques in Bangladesh

Abstract

The choice of flood control techniques in Bangladesh is reviewed in the context of a case study on the impact of a small-scale polder, the Dhaka-Narayanganj-Demra (DND) Project. The results of a questionnaire survey among the urban floodplain residents, who have settled inside the polder and a control population from outside the polder, indicate that the project has achieved significant flood alleviation but has also induced considerable environmental degradation due to stagnation of water within the enclosed embankment. The project also experienced numerous problems of structural instability of embankments during major flood events. An attempt is made to extrapolate some of these adverse environmental impacts of the polder to the compartmentalization scheme, which has been proposed by a UNDP-sponsored Flood Policy Study as an innovative technique for floodplain management in Bangladesh. The findings of the study, however, do not provide an adequate basis for assessing viability of the proposed compartmentalization scheme. Nonetheless, the study illustrates the usefulness of questionnaire surveys among floodplain residents for obtaining data for project evaluation.