TRANS-BOUNDARY WATERSHEDS: The Ganges, the Brahmaputra and the Meghna (GBM) river basin encompasses a total area of about 1.72 million km2, of which only 7 per cent is located within Bangladesh. They originate from three different sources and their geographical, hydro-meteorological, hydrological and morphological characteristics are quite diverse. The high and low water flows of the Ganges and the Brahmaputra occur at different times, suggesting watersheds with diverse topographical and hydrological characteristics. Among the 57 trans-boundary rivers, Bangladesh shares 54 rivers with India and three with Myanmar. The annual cross-border river flows in Bangladesh are estimated to be 40,000 m3/s, of which the three main rivers (GBM) contribute around 31,000 m3/s. Of the latter amount, some 54 per cent is contributed by the Brahmaputra, 31 per cent by the Ganges and nearly 14 per cent by the tributaries of the Meghna (BDP 2100). As Bangladesh is located in the low lying delta of the Ganges-Brahmaputra-Meghna basin, water resources management is complex and highly sensitive to upstream developments. Therefore any intervention, including diversion, use or storage of flows from the transboundary rivers are of major challenge for Bangladesh.
Both India and China, being the powerful upper riparian countries, share a common view that promotes bilateral approach in dealing with other riparian countries in the region, rather than more rational and effective multilateral approach. Although India has shown a shift in its attitude towards a more multilateral approach, however, the initiative is in its early stage and no visible progress has been made. Lack of multilateral cooperation, contradictory governmental policies and differences in priorities in the short-term and long-term water resources management plan have lead to a conflict among the countries sharing the most complex watersheds in the world.
The upper riparian countries, especially the powerful ones, often project their interests disregarding those of the downstream neighbours. It has been a great concern for Bangladesh not only for the differences in perspective, priorities and watersheds management policies among the riparian countries, but also the sheer absence of multilateral watershed data sharing agreement between them. It is very difficult for Bangladesh to develop strategic plan to address the hydro-climatic risk posed by climate change and global warming.
Within the framework of conflicts stated above and in absence of data sharing protocol, the trans-boundary watersheds have become hotspots for Bangladesh that need to be addressed by the BDP 2100 with priority and urgency. Therefore, a sophisticated and scientifically advanced approach needs to taken to reconstruct the hydro-climatic conditions in the watershed where Bangladesh has no field data nor has it access to it. This approach will help Bangladesh gain upper hand in water diplomacy where Bangladesh enjoys a very limited leverage.
The Bangladesh Delta Plan 2100 must take an observation-independent approach to construct the hydro-climatic conditions in the GBM transboundary watersheds. A dynamical downscaling approach, necessary to resolve the complex terrain features of the watersheds, uses conservation of mass, momentum and energy equations in a large-scale regional climate model (RCM) to produce small-scale spatial and temporal atmospheric conditions. In addition, high-resolution topographic data (ASTER Global DEM), soil parameters (Soilgrids) and land use/cover data (Global Land Cover Characterisation, GLCC) dataset can be incorporated in the modeling framework. A hydrological model needs to be coupled with the RCM to simulate downscaled atmospheric variables to stream flow at desired locations. A coupled modeling framework could be a useful tool for BDP 2100 to simulate small-scale climate conditions in the watersheds and formulate strategic planning for the Delta. This effort can also be directed to address the water quality and ecological health of the watersheds. The coupled hydrologic model will also be used to determine the impact of point and non-point sources of pollutions across the watersheds and the river systems.
WATER QUALITY: A comprehensive and careful strategy is required to restore and maintain the physical, chemical, and biological integrity of the surface and ground waters of the Delta. The primary goal of the strategy would be to restore and protect the aquatic resources of Delta. It would be a significant challenge to preserve the water quality due to industrial, agricultural and other anthropogenic activities not only in the GBM basin within the country but also in the upstream transboundary watersheds. Therefore, it is important that the BDP 2100 introduce a comprehensive plan to develop water quality standards for water bodies such as lakes, haors, rivers, estuaries, coastal waters and ground waters. The plan should identify impaired water bodies, which require stringent controls to meet the water quality standards. If necessary, the Water Act 2013 should be amended to include a control mechanism so that the water quality standards can be maintained. One of the mechanisms could be, for example, a quantitative and adaptive measure called daily maximum loads (DMLs) for each water body depending on its ecological health.
A DML or any alternative approach should include a calculation of the maximum amount of a pollutant, such as N, P, C, BODs and other organic and inorganic materials that can be discharged by industries, agriculture, municipalities and others in a water body and still meets water quality standards. A DML is both a quantitative assessment of pollution sources and pollutant reductions needed to restore and protect Delta waters. The Delta waters will be assessed, and restoration and protection objectives systematically prioritised, and DML and alternative approaches adaptively implemented to achieve water quality goals.
Eutrophication is an excessive loading of water with nutrients, dissolved substances containing P, N and Si needed by organisms to grow. It is a global aquatic environmental crisis, which requires a holistic approach to control through sustainable management of upstream catchments and conservation of water resources. Nutrient loading of surface waters is caused by increased inputs of fertilisers from agricultural activities in the upstream catchments, atmospheric deposition and municipal effluents. The negative impact of eutrophication on marine ecosystem includes-- algal bloom and dissolved oxygen demand, depletion of oxygen in lower water layers that triggers massive fish kill and destruction of benthic organism. Mitigation of the negative effects of eutrophication requires reduction of nutrient inputs (fertilisers) and an ecosystem-based management strategy.
DML can be a planning process for attaining water quality standards and developing corrective measures and control eutrophication. It is true that it would cost money and resources to meet the DML criteria, however, the industries, municipalities, farmers and others must not discharge uncontrolled pollutants and nutrients in the water bodies, as they have been doing for years. It is expected that the DML will be a core element of overall efforts to protect and restore water quality and preserve the ecosystem. A constant scientific review of DML's effectiveness on a particular water body is necessary and an adaptive approach should be taken to achieve its goals.
DELTA SCIENCE FOUNDATION: As the BDP 2100 calls for a comprehensive and integrated water resources management through adaptive delta management practices, it is important to make a comprehensive research and development programme that must go parallel with the development projects in the Delta. A Delta Science Foundation (DSF) may be established that will be governed by a group of professionally active and respected scientists, engineers, academics and social scientists. The Foundation will formulate research programmes consistent with the BDP 2100 goals. Research programmes will be funded to advise the BDP 2100 to implement projects and use adaptive management plan.
The Foundation will operate based on the set of strategy set out by a Board. The Foundation will fund research and education in the fields of science and engineering related to water, climate, socio-economics, and water resources management. It will do this through grants and cooperative agreements with colleges, universities, K-12 school systems, businesses, informal science organisations and other research organisations across Bangladesh. In addition, the Foundation will fund graduate, doctoral and postdoctoral fellowships. The Foundation may not operate any laboratory facilities itself but may support Universities and colleges and or other research institutions to develop their research labs and computational facilities, research vessels and special laboratories for testing or computing. The Foundation will also support cooperative research between universities and industry, and participate in international scientific and engineering research efforts, and educational activities at every academic level. The DSF will also formulate a plan to retain the talents in this sector.
Dr Quamrul Ahsan, PE, is National Water Resources Management Specialist, BWDB, former Senior Project Manager, HydroQual, Inc, NJ, USA and former Assistant Professor, IWFM, BUET