Movement of people from one location to other caused by various factors such as economic, social, political, environmental etc., are termed as drivers of migration (Black et al. 2004). But forced migration in recent decades becomes a common phenomenon in the world. Forced migration that caused by environmental disaster or natural disasters is termed as environmental refugee (Bates 2002; Warren 2015). The environmental events such as land degradation, soil erosion, and droughts have severe effect on farmers that leads to migration of farmers from rural agricultural area to urban industrial area for getting employment (Larson et al. 2004). There are various studies that reveals the relation between environmental degradation and migration such as land degradation and migration (Shah 2005; Gupta and Sarma 2010), river-bank soil erosion and migration (Uddin and Basak 2012; Das et al. 2013) deforestation and migration (Ravindranath and Sukumar 1996), and common property resource degradation and migration (Chopra and Gulati 2001; Mahanta and Das 2012).
In India river-bank erosion becomes a cause of force migration as it create various types of socio-economic problem (Das et al. 2013). As per the information of National Disaster management Authority (NDMA 2014), Bihar and Assam are two highly flooded and erosion affected states in India. West Bengal state is also affected to some extent (Chatterjee and Mistri 2013). Assam, which is mostly a plain state in northeast India, has been heavily affected by river-bank erosion since 1950. The state has lost 12.6 thousand hectares of land, which displaced 77.8 thousand people in 2014 (GOA 2014). There are a handful of studies which have endeavored to see the relation between river-bank erosion and migration in Assam. Till 1985, Assam lost about 7.4 % of its total area due to river-bank erosion and that leads to displacement of five thousand people (Goswami et al. 1985). Phukan et al. (2008) estimate that since 1960 to 2008, the Brahmaputra River wiped out more than 4000 sq. km of land and displaced more than 25 thousand villages. The river bank erosion caused various socio-economic problems and compels the populace to migrate in search of livelihood (Mili et al. 2013; Ahmed 2016). In this context the study examines the linkage between riverbank erosion and population migration with an analytical approach and the factors responsible behind such migration.
Review of Related Literature
The theories on internal or rural-urban migration contend that migration happen due to the factors like wage differences, differences in employment opportunities as well as health and education facilities etc. (Fei and Rannis 1962; Todaro 1970). The rural people migrate when the benefits arise in the urban areas is more than the costs (Sjaastad, 1960). In contrast, minimization of risk and maximization of joint income are the influencing factors of migration according to the New Economics of Labour Migration (NELM) theory (2001). In recent decades environmental events like flood and riverbank erosion becomes an extreme event, which forces people to migrate by affecting their income sources. These make migration a way to minimize the risk induced by environmental events (Dercon 2005; Black et al. 2011).
In Bangladesh, Yamuna River affect and displaces large number of people by eroding its bank areas and forces people to migrate somewhere else for sustaining their livelihood (Uddin and Rahman 2011;Uddin and Basak 2012). The erosion severely affects the socio-economic livelihood of the riverbank inhabitants. People affected by erosion lose their agricultural land as well as properties that affect their sources of income and lead to entrapped poverty. Although erosion displaces many families, but in low eroded areas victims adopt some coping strategies like sale of land and livestock, shifting to new char land in Bangladesh to adjust with the erosion problem (Karim 2014). In Bangladesh, the loss of agricultural land and landlessness due to erosion is considered as the major contributory factor behind poverty (Rana and Nessa 2017). Adopting the origin and destination survey method in Bangladesh, Rana and Nessa (2017) observes that two-third populace of the surveyed villages migrates permanently from one union to another union by getting support from their neighbors, relatives, friends and they stayed in the destination place at lower living cost in comparison to the origin.
In the context of India, Das et al. (2014) reveals the impact of riverbank erosion in their study. The study finds that impacts of riverbank erosion are multifarious: social, economic, health, education and sometimes political, which creates forced migration. The socio-economic impacts categorized as short term (loss of home, agricultural land, jobs and assets) and long term (direct effects on the living conditions of affected populations and indirect effects on human health and development, also referred to as the accumulation of human capital, which includes schooling of children and health status of mothers and children) impacts (Das et al. 2017). The forced migrants faces different form of risk of insecurities due to erosion, such as economic insecurity due to unemployment, erosion of capital and indebtedness, social insecurity due to deprivation of civic rights, health insecurity due to lack of basic infrastructure, etc. Therefore, Das et al. (2017) suggest that there should be specific policies to protect civic rights of those migrants and it would have been better to introduce gender specific policy (especially for female protection). Among various impacts loss of property in the form of cropland, cattle, and houses made the households more vulnerable to poverty and forces to migrate (Chatterjee and Mistri 2013).
Assam in the north-east India largely affected by flood and riverbank erosion in the lower reaches of Brahmaputra valley (WRD). Reviewing the population redistribution problem in Majuli sub-division of Assam, Nayak and Das (Undated) reveals that shrinkage in land area of the island over the years due to soil erosion by the mighty Brahmaputra is the main problem. Due to loss of farm and homestead land, the poor people fall into poverty trap. The river bank erosion destroys the existing modes of production and ways of life, breaks the family and community relations, as well as threatens cultural identity of the people. Mili et al. (2013) in their study on Golaghat district of Assam, India, mention about various problems that arise due to flood and erosion such as displacement, loss of agricultural land and home, psychological effect, poor transportation system and problems in education. Such various forms of socio-economic problems induced by riverbank erosion compel victims to move to nearby area in search of livelihood (Baishya 2013). In another study, Ahmed (2016) finds that the impact of riverbank erosion is too severe in Barpeta district of Assam, India. Most of the affected people migrate from the eroded areas as they lose the income source. Agriculture being the main source of income, loss of crop land due to riverbank erosion they actually lose everything. In addition to that, as they don’t have any other coping strategy they are forced to migrate to nearby towns and cities to stabilize their income fluctuation. They mostly get employment in informal sector like pulling thela, rickshaws, unskill construction works of buildings, roads, etc.