The Jamuna-Brahmaputra River, Bangladesh

Bangladesh is dominated by three great rivers – the Jamuna-Brahmaputra, Ganga and Meghna – that combine to feed sediment into one of the World’s largest deltas in the Bay of Bengal (Figure 21.1). Bangladesh has been shaped by, and is dependent upon, its rivers, which provide fertile soils and a diverse flora and aquaculture but also bring significant flood hazard and risk to infrastructure for a large and growing population. Current anthropogenic stresses, in terms of changing climate, water diversions, pollution and sediment extraction, are posing new pressures to the river and its inhabitants (Best, 2019). The people of Bangladesh have adapted their lifestyle for centuries to live with river flooding – frequently moving their temporary bankside homes, planting on newly emergent river bars, and sometimes raising their homesteads above water level in flood periods (Paul, 1997). However, a growing population, coupled with the expansion of infrastructure and economic development, has resulted in an increase in the intensity of flood damage (FPCO, 1995; Paul, 1997; CPD, 2004). The lives of many millions of Bangladeshi citizens are reliant on these rivers, with up to 2.3 million people living on the riverine islands alone (Schmuk-Widmann, 2001). Bangladesh’s rural economy relies upon annual ‘normal’ floods to bring moisture and fresh sediments to the floodplain soils (Paul, 1997): for instance, two of the three seasonal rice varieties (aus and aman) cannot survive without floodwater and the fish caught both on the floodplain during flood season and from the many floodplain ponds (‘beels’) provide the main source of protein for many rural populations (Chowdhury, 1994; Paul, 1997; de Graff, 2003; Shankar et al., 2004). However, the effect of ‘abnormal’ floods can be devastating and result in appreciable damage to crops and houses, severe bank erosion with consequent loss of homesteads, schools and land, and loss of human lives, livestock and fisheries (BDER, 2004; Shankar et al., 2004). For example, in the 1998 flood, over 70 % of the land area of Bangladesh was inundated, affecting 31 million people and 1 million homesteads (Chowdhury, 2000). The 1998 flood, which had an unusually long duration from July to September, claimed 918 human lives and was responsible for damaging 16 000 and 6000 km of roads and embankments, respectively, and affecting 6000 km2 of standing crops (Chowdhury, 2000). In the 2004 floods, over 25 % of the population of Bangladesh, or 36 million people, was affected by the floods; 800 lives were lost; 952 000 houses were destroyed and 1.4 million badly damaged; 24 000 educational institutions were affected, including the destruction of 1200 primary schools; 2 million government and private tubewells were affected, and over 3 million latrines were damaged or washed away, this increasing the risks of diarrhoea, cholera and other waterborne diseases. Also, 1.1 million ha of rice crop was submerged and lost before it could be harvested, with 7 % of the yearly aus (early season) rice crop lost; 270 000 ha of grazing land was affected, 5600 livestock perished together with 254 000 poultry and 63 Mt of lost fish production (BDER, 2004; CPD, 2004). In the districts that are dominated by the Brahmaputra-Jamuna River, the 2004 flood damage to infrastructure (homes, roads, culverts), tubewells and latrines, with ensuing unemployment of many of the population, were some of the areas of critical impact. The total cost of the damage caused by the 2004 flood is estimated at $7 billion (CPD, 2004).