Pre-Feasibility Level Study of Sharada-Dang Valley Irrigation Project, Dang

Project Description

The Dang valley is one of the largest valleys of the country located in Dang district. The Dang valley with the irrigable area of about 65,950 ha has potential irrigable area of about 60,000 ha including Deukhuri valley and Tulsi-Dang. The proper Dang valley has total irrigable area of about 43,000 ha, part of which is being irrigated from seasonal streams and rivers. The year round irrigation coverage in the valley is limited to small proportion of the area commanded by a number of farmer managed irrigation systems and deep tube wells. The main objective of this Project was to carry out prefeasibility level study to identify various components and alternatives of the project such as dam, inlet tunnel, outlet, power generation, canal alignment, command area, and required structure of the main canal. The project also aimed to have a general picture of the impact of this project on the current socio-economic status of the area. Since large dams have been rapidly establishing themselves as a major civil-engineering structure in the sector of water-resource management, the significance of project is more highlighted as the first ever study in the sector of irrgation engineering in Nepal.

Assignment Description

Carried out detailed hydrological study of the Sharada River; catchment characteristics, drainage system, water-uses, and water availability. • Conducted geological and geo-technical investigation of the area. This included geophysical investigations at the dam site of the proposed diversion project using two Dimensional (2D) Electrical Resistivity Tomography (ERT) methods (2000 m). • Assessed the availability of potential construction materials and seismicity of the area. • Prepared socio-economic profile of the area to ensure social safeguard, and prepared agricultural development plan. • Proposed diversion plan for the irrigation development that included: • Concrete Faced Rockfill Dam: 158 m • Net Command Area: 7, 900 ha • Length of Main Canal: 19.27 km • Canal structures: Superpassage-61 Nos; Village Road Bridge-25 Nos; Canal Syphon-8 Nos • Gross Reservoir Capacity: 405 Million Cu. M. • Diversion Tunnel: Length: 5 km, Diameter: 4 m, Discahrge Capacity: 20.5 m3/s • Net Head Available for Power Generation: 100 m • Hydropower Capacity: 17.6 MW • Conducted Initial Environmental Examination (IEE). • Conducted detailed cost estimate for the pre-feasibility level study, including both civil infrastructures and electro-mechanical components of the hydropower. The estimated project-cost was NPR 17,522,325,188.00. • Prepared design drawings, and conducted economic and financial analysis. The estimated EIRR is 11.45 %.