Sustaining water resources for food security in Bangladesh

[摘要] Bangladesh intends to revise and update its National Water Management Plan. The study reported here follows on from the Bangladesh Integrated Water Resources Assessment work of 2010-2014 and aims to provide information to support the revision. This report describes the first phase of the study, which was a preliminary study to scope out the second phase of detailed modelling andscenarios analysis. The geographic scope of the study was the irrigation intensive northwest and north-central regions which are vital for future food security of Bangladesh.The main findings are:1. Groundwater irrigation is the main factor behind the current self sufficiency in rice production. Sustaining groundwater irrigation is vital for the future food security of Bangladesh.2. The increased area of irrigation and increased volume of groundwater pumping over the last three decades has contributed to declines in groundwater levels. The regional average trend indeclining groundwater level appears to be at least partly explained by the trend in increasing irrigation rather than the absolute level of irrigation. A halt in the trend of increasing irrigation may see a reduction in the trend of decreasing groundwater level, albeit at lower groundwater levels.3. The lower groundwater levels referred to above, combined with further lowering in drought years, will in some areas cause difficulties with access for drinking water and irrigation water in the future (as they already do in some areas).4. Within the region are areas, particularly in the Barind Tract, of unsustainable over-use of groundwater.5. Lower groundwater levels in the pre-monsoon period have meant a shift towards less groundwater moving to streams and more water moving from streams; more water infiltrating through the land surface, with a probable reduction in surface runoff and reduced return flow to streams.6. Aquifers are losing water to most major streams. The exceptions appear to be above junctions of major rivers and/or in areas where landscape is flattening. The influence of the streams on the groundwater appears to be constrained to within a few kilometres of the stream.7. The total surface water-groundwater fluxes for the northwest region appear to be smaller than previously thought and are not likely to be more than 20 billion cubic metres per year.8. Socio-economic development through industrialisation that creates wage income is a major contributor to both household income and nutritional well-being.9. Women should be incorporated into mainstream development activities to enjoy better livelihoods.Based on the findings, we recommend that studies should be conducted to:1. Examine the impact of different external drivers (such as population growth, climate change, upstream development, construction of barrages, etc.) on the overall water balance andsurface-water groundwater interaction, availability, and sustainability.2. Examine the impact of future water availability on the irrigated agriculture, regional socioeconomy, livelihoods, and the environments and, in particular, conduct a social cost-benefitanalysis of potential investments or policies.3. To enable the previous two aspects, develop regional scale understanding and evaluation of the surface water and groundwater resources, surface water and groundwater interaction, recharge/discharge mechanisms and trends, sustainable limit of groundwater use using hydrological and hydro-geological information, and detail modelling.The findings and recommendations are based on a preliminary examination of agricultural production, regional water balances, groundwater levels and exchange of water between the groundwater and surface water, together with a study on econometric assessment of livelihoods outcomes within the northwest and north-central regions of Bangladesh.

[发布机构] CSIRO

[学科分类] 地球科学(综合)