Bangladesh Univ of Engineering & Tech (BUET), Dept of Water Resources Engineering

Management of Rivers for Instream Requirement and Ecological Protection

This collaborative research on Instream flow requiremnt was conducted in the Deaprtment of Water Resources Engineering at Bangladesh Univ of Engineering & Tech (BUET) with the finacial assistance of the Royal Netherlands Embassy, Dhaka.

Other participants were Delft Hydraulics, Netherlands, and Water Sector Organizations in Bangladesh (BWDB, JRC, WARPOO, IWM, and CEGIS)

Executive Summary
Historically, water resources has been managed in Bangladesh from supply perspective with an emphasis on maximizing economic growth from the use of water. Specifically, flood management and irrigation development have been the main concern without much attention to low flow and instream flow management. With increased awareness about environmental issues in 1990s, the focus now has been on year round water management. Also instream flow requirements are explicitly recognized in the National Water Policy and National Water Management Plan.

Flow regimes of rivers in Bangladesh have already been degraded significantly due to human interventions, mainly upstream withdrawal of water. Ever increasing water resources demand and utilization in the upper riparian country will increasingly have an effect on the water availability in the river system of this country as most of the catchment areas lie outside its territorial limits. There are large-scale plans for diverting water from the Brahmaputra and Ganges Rivers to the drought prone areas in India which will not only affect the low flow conditions but also the seasonal variability of flow will be altered affecting the entire annual hydrograph. In view of these assessment of instream/environmental flow has become very urgent. Furthermore, on a local and regional scale environmental flow requirements are needed for the main and secondary rivers in which flows are decreasing due to local changes, for example through water diversion and siltation at off-takes and bifurcation points. Many methods have been developed over the last 30 years, primarily in the United States, Australia, Europe, and South Africa to establish environmental flows. Some techniques were developed for protection of specific (often threatened) species, while others were developed for broader ecosystem protection. These techniques have now been applied in over 25 countries, resulting in a considerable body of experience in developed countries, but only limited experience in the application of these methods in developing countries.

In Bangladesh no systematic study and research has been done for defining environmental flow requirements. The instream requirement set forth in different plans until now has been on ad hoc and empirical basis. From a river management point of view, scientifically justified methods and guidelines are needed for determining flow requirements to safeguard aquatic environment, livelihood of subsistence users, and requirements of downstream users. In this regard water management in this country lags behind in the development of appropriate management models for recommending flow regimes considering environmental and ecological aspects.

The main objective of this research is to:

  • understand the issue of instream flow requirements of selected rivers in terms of their functions and problems, and suggest a suitable methodology for assessing flow requirements,
  • gain experience in environmental flow assessment methods,
  • develop capacity in multidisciplinary research involving hydrologists, fisheries biologists, ecologists, academicians, as well as water professionals and practitioners, and
  • suggest further research needs and steps to establish a comprehensive environmental flow assessment program.

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