The Meghna-Dhonagoda Embankment (MDE) is an example of a flood control scheme which also regulates irrigation and drainage of the area inside it. This intervention in the natural functioning of the environment - intended to reduce the often catastrophic impacts of flooding on mankind - itself may have substantial impacts on the environment and humans in the short and long run. These impacts are not well understood and thus are not fully taken into consideration at the time of inception of the project.
This study assesses the relatively short-run environmental impacts of the MDE using a statistical analysis. The data used in the study are cross sectional and are taken from a survey conducted in 1992, about 4 years after completion of the embankment. Bivariate and multivariate analysis of direct and indirect indicators were used to analyse the effects of the embankment on agricultural yields, nutrition levels, and wealth. The inferences drawn acknowledge the fact that many factors besides the embankment operate on these indicators and that isolating the effects of the embankment is difficult.
The results of this analysis indicate that the MDE is associated with both positive and negative impacts on the population inside the embankment relative to those outside, and it is difficult to generalise about the overall impact of the embankment on welfare. The most beneficial impacts correlated with the embankment are a higher level of agricultural yields and economic prosperity among the households inside relative to the households outside. On the other hand, fish catch and intake of fruits and vegetables are both found to be lower inside the embankment. One possible cause of virtually all of these impacts is the shifting of land use to HYV rice cultivation within the embankment area. However, due to the cross-sectional nature of this study, any causality implied by these correlations must be considered with caution: some differences between conditions in the areas which are now inside and outside the embankment may have been present before the embankment was built.
Only time will tell the full extent of the impacts of the MDE - beneficial as well as adverse -as these impacts evolve and a new equilibrium is reached. Whether the higher levels of rice production and wealth inside the embankment, found four years after its completion, can be sustained in the long run remains a vital question that will need to be revisited regularly for several more decades.