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Research | Current Research | Previous Research |
DEVELOPMENT OF FLOOD MAPS OF THE SURMA-KUSHIYARA BASIN The study ‘Management of Rivers for Instream Flow Requirements and Ecological Protection’ of BUET-DUT Linkage Project concerns environmental flow assessment for three selected river system of Bangladesh: Surma-Kushiyara, Teesta and Gorai river. Instream flows sometimes called environmental flows provide the water that is left in a river eco-system or released into it for specific purpose of maintaining the condition of the ecosystem. Three types of methods were selected for environmental flow assessments for this study include hydrological methods, PHABSIM method, and ecotope method. The hydrologic methods basically provide reconnaissance level information regarding IFR and they do not consider the river functions, characteristics or the problems explicitly. PHABSIM is an incremental method in the sense that it predicts the changes in fish habitat resulting from changes in flow. The ecotope method is a new approach for assessing environmental flow requirements and it enables integration of river and floodplain ecosystems and their functions. Ecotopes are land units that are determined by various aspects and processes occurring in the landscape. The assessment of environmental flows therefore requires an approach that is broader than the instream flow methods used in most cases. Flood map of the study area is an integral part of the ecotope method. Flood maps are generated to identify spatially defined flood characteristics such as flood frequency and duration. These results are combined with the ecotope map of the present situation to define the ecotope model. The main objective of this research is to: · slection of scenarios considering proposed Dam and Barrage in the U/S of Barak river; · dvelopment of series of flood maps of the Surma-Kushiyara basin for different scenarios using MIKE GIS and MIKE FLOOD and · cmparison of outputs of the MIKE GIS and MIKE FLOOD.
MANAGEMENT OF RIVERS FOR INSTREAM REQUIREMENT AND ECOLOGICAL PROTECTION Introducing Environmental Flow Assessment in Bangladesh, Multidisciplinary Collaborative Research 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. 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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Last updated : Monday September 18, 2006 |