Environmentally-induced migration is a key issue for many parts of the world. Bangladesh is a clearly defined region where such a social problem could take place due to a range of environmental processes. Bangladesh, especially the delta section, has already experienced both rapid environmental change from natural disasters such as tropical cyclones and floods, and more slow change due to rising sea levels and river bank erosion. This thesis examines the physical background to environmental change in Bangladesh and explores, through 355 questionnaires and the same number of in-depth interviews, the social impact of this, both in the regions directly affected, but also in the internal migration destinations. Most of the country’s rivers have shown discharge increases over the last few decades; this is particularly notable on the main river system at Bahadurabad through which 60% of the discharge passes. However, the mean flow downstream at Harding Bridge shows statistically significant decreases in the dry season due to the construction of the Farakka dam in the 1970s. The frequency, and severity, of monsoon flooding has been increasing in recent decades, in line with the general increase in river flows. These changes increase the frequency of river bank erosion. As a case study the region of Mehendiganj on the main channel is chosen, where the eastern end of the island is eroding rapidly, at a rate of ~3.2 km2yr-1 during the period 1972-2012. From interviews in both this region and the coastal region subject to threat from cyclones and storm surges, coping mechanisms of local people to environmental change, including displacement and migration, whether temporary or permanent, are investigated. The differential response of people remaining near their homes, moving to regional centres, or migration to major cities is investigated. The impact of increasing migration on the destination communities is also considered.
The current study provides evidence that environmental change directly causes migration. Environmental change is more strongly related to short distance migration. Long-distance moves are generally affected by other drivers while environmental drivers are secondary or background drivers in this case. Long-distance moves are generally undertaken for financial and social reasons, in particular where there is a pre-established migrant network. Thus, the displaced poor were found to not move far, because of a combination of factors relating to the social and economic advantages of re-establishing themselves locally. However, many respondents were found to have been displaced multiple times, which increases the probability that they will be forced further afield, most likely to urban areas, as environmental refugees.
The study also presents a new understanding of the role of environmental change in causing migration and its relation to societal consequences. Therefore, the concept of vulnerability to environmental change, adaptive capacity and migration process has been applied. The study developed vulnerability Index (VI) to assess environmental change vulnerability in the four coastal rural sub-districts and the two cities in central region. The VI compared the various regions’ vulnerability to adaptive capacity, sensitivity and exposure and differential vulnerability. The results suggest that both permanent and non-permanent migration processes have a close relation to vulnerability and non-permanent migration has a close link to adaptive capacity. The study found that the sub districts of Shyamnagar and Mehendiganj may be more vulnerable in terms of sensitivity and exposure and less adaptive capacity, whilst Mehendiganj is more vulnerable in terms of exposure to hazards than other sub-districts. These two vulnerable regions also have shown higher number of migrants, from Mehendiganj as permanent migration whilst from Shyamnagar as non-permanent migration. Therefore, migration is a significant approach for reducing vulnerability to environmental change by increasing adaptive capacity. Similarly, as migration destinations Dhaka is more vulnerable in terms of sensitivity, exposure and adaptive capacity than Comilla. The findings of this research confirmed that poor migrants are the most vulnerable in the city. This group has less adaptive capacity than old migrants or poor local people due to low level earning, limited access to resources and location and settlement pattern.
