Bangladesh Integrated Water Resources Assessment: final report

[摘要] The Bangladesh Integrated Water Resources Assessment project studied water resources in Bangladesh from both a physical and a socio-economic perspective. We examined both water supply and water demand issues, where demand has both physical components (irrigation water demand) and socio-economic components (urban and industrial demand, demand for food and hence irrigation). We examined historical water use and crop production, and the likely future water use influenced by climate change population growth and a growing economy. We also examined the impacts of changing water on the national economy and on the vulnerability of individuals and households. The annual average volume of rain falling on Bangladesh (excluding the eastern hills which are outside the region we considered) from 1985 to 2010 was 284 km3, of which 11 % fell in the dry season from November to April. The annual average (1980 to 2009) inflows of the combined main rivers was 981 km3; the dry season (November to April) inflows were 15 % of the total. The average annual recharge to groundwater is not well known, with our estimates and estimates in the literature varying from 28 km3 to 65 km3. Water use in Bangladesh is dominated by irrigation with estimated annual use varying from 25 to 33 km3 of which 80 % is from groundwater. Domestic and industrial demand is estimated at about 2.7 km3 per year, which is projected to increase to about 4.1 km3 by 2050. Groundwater is overused in the Barind and around Dhaka, and there are concerns about the level of use elsewhere. Climate change is projected to increase extreme rainfall and temperatures and hence exacerbate floods and droughts; it may also reduce land availability in the coastal zone because of greater flooding. However, natural variability of rainfall and river flows is expected to dominate over climate change, at least up to 2050. The ways in which climate change may impact groundwater are complex and poorly understood: larger flows and floods could enhance recharge, whereas greater plant and crop water demand could increase natural groundwater use and irrigation withdrawals.Maintaining and increasing food production for the growing population without increasing (and probably reducing) the use of land and water for agriculture will be an immense challenge, particularly in view of the concerns about overuse and the possible impacts of climate change. Bangladesh is already increasing crop yields and there is good potential for further increases. Thus it is well placed to meet this challenge, even when projected climate change reductions to agricultural production are factored in. The rapid economic development of Bangladesh in the last two decades is expected to continue. We found that climate change impacts on macroeconomic indicators were relatively small, with climate change reducing GDP by -0.327% by 2050. Population growth dynamics, TFP growth and trade policy may have more profound effects on the economy than projected climate change. Numerous other drivers of change not considered here could also prove to have significant impacts including urbanization, the changing age structure of the population, external migration and remittances, infrastructure development and exogenous shocks to the economy such as the agricultural commodity price shock that occurred in 2008. Poorer people are more vulnerable to water stresses such as droughts and floods. Combining the incidence of water stresses with poverty measures, we find that the districts most vulnerable to droughts and floods are in the coastal zone and in the central districts around Dhaka. The northeast, central districts (other than those around Dhaka) and the Ganges corridor are all fairly vulnerable to water problems. Lifting people out of poverty is a worthy end in itself, and doubly so because it will reduce the vulnerability of poor people to water related stresses. General economic development is the main factor in future rural

[发布机构] CSIRO

[学科分类] 地球科学(综合)