Assessment of River Connectivity Using Genetic Approach in Chitwan Annapurna Landscape

The landscape is home to numerous rivers, including the Marshyangdi and Budhi Gandaki rivers, which are of particular interest due to their high gradient topography and potential for hydropower generation. The Marshyangdi River originates from the northern slopes of the Annapurna Himal and runs through Manang, Lamjung, Gorkha, and Tanahun districts, eventually joining the Trishuli River at Mugling. The river basin spans an area of 410.59 km2, with an elevation ranging from 318m to 8124m above sea level. The Budhi Gandaki River, on the other hand, originates from the Manaslu Himal and reaches an elevation of over 8000m in Gorkha district. The river has a length of 128.5 km and a catchment area of 537 km2. Unlike the Marshyangdi River, the Budhi Gandaki River has no man-made barriers, making it an ideal reference point for assessing the impacts of dams and weirs on river ecosystems. The construction of dams and weirs on rivers has significant impacts on river ecology and aquatic flora and fauna. The disruption of the longitudinal corridor of rivers, particularly for migratory fish species, can lead to declines in fish populations and alter the structure and function of river ecosystems. In the case of the Marshyangdi River, which has multiple dams and weirs, the impacts on river ecology are likely to be more pronounced. The study aims to assess the impacts of dams and weirs on the river by evaluating the fish assemblage of selected species in the Marshyangdi and Budhi Gandaki rivers. The study will focus on four fish species, which are commonly found in the region. The research will involve a review of past fish studies in the Marshyangdi and Budhi Gandaki rivers, identification of indicator fish species, and a survey of fish species in the sub-basins of the two rivers. Genetic materials will be collected from live key indicator species for further analysis. The study will provide valuable insights into the impacts of dams and weirs on river ecosystems, particularly in the context of the Marshyangdi and Budhi Gandaki rivers. The research will contribute to the development of effective management strategies for managing complex social-ecological systems, which are essential for ensuring the sustainable provision of ecosystem services. The study area, Chitwan Annapurna Landscape (CHAL), covers an area of 32,090 km2 and spans 19 districts. The landscape is home to numerous rivers, including the Marshyangdi and Budhi Gandaki rivers, which are of particular interest due to their high gradient topography and potential for hydropower generation. The study will be conducted at eight sites, four from each river, and will involve a review of past fish studies, identification of indicator fish species, and a survey of fish species in the sub-basins of the two rivers. The Marshyangdi River sub-basin covers an area of 4211 km2 and originates from the south-east flank of the Annapurna Himal. The river has a length of 45 km and a catchment area of 410.59 km2. The river flows through Manang, Lamjung, Gorkha, and Tanahun districts, eventually joining the Trishuli River at Mugling. The river basin has a high gradient topography, with an elevation ranging from 318m to 8124m above sea level.