Project Discription : Upper Karnali Project Discription : Upper Karnali Location Click here for Upper Karnali (Kr-1A) Site Photograph The Upper Karnali project is one of Nepal’s most economically attractive run-of-river diversion schemes (300 MW), with daily peaking capacity and high firm energy. The site is located in the Far Western Development Region of the Kingdom at latitude 200 50′ N, longitude 810 30′ E and at an elevation below 1,000 m. Project facilities will be located in three districts: Surkhet, Dailekh and Achham. The site is 670 km from Kathmandu and 50 km from Birendranagar which is the nearest regional airport. An all weather road from Birendranagar to Jumla is under construction and will pass immediately by the headworks. Road construction has reached the Karnali river bend, 50 km from the site. Upgrading of 92 km of the Surkhet-Jumla road between Surkhet and the headwork, and the construction of a new 20 km long access road between the headworks and the powerhouse via the village of Thalpata will be required. Hydrology The Upper Karnali is a tributary of the Karnali River and the catchment area at the project intake site is 20120 km2. The hydrology is based on Gauging Station No. 240 at Asaraghat. The river is snowfed. The mean annual flow estimated at the headworks is 500 m3/sec. and the 1000 year design flood is 6830 m3/sec. The estimated sediment yield from the catchment is 2240 tonnes/m2/year. Layout In 1989 Himalayan Power Consultants (HPC), a consortium of Canadian and American consulting firms, completed a hydropower ranking of potential sites within the Karnali River Basin. The economic ranking of the six most promising sites in the 100 to 500 MW range prepared at that time showed Upper Karnali to be the most attractive site in the basin. This site was subsequently studied to pre-feasibility level of design by HPC. For this study, a programme of field investigations, including topographic surveys, drilling, test pitting, geophysical surveys and geological mapping, was undertaken. Prefeasibility level designs, cost estimates and benefit evaluations were carried out, as was a preliminary assessment of environmental and socioeconomic impacts of the project. Feasibility sudies commenced on late October, 1996 and will be completed at the end of September, 1997. These studies include additional topographic suveys and mapping, drilling, test pitting, geophysical surveys, geological mapping and laboratory testing to augment those carried out during the prefeasibility studies and to accommodate changes made to the project arrangement at the outset of the feasibility studies. In view of the unique bend which occurs in the reach of the Karnali River in which this project is located, the layout is very compact. The tunnel is only 2.4 km long thus minimizing tunneling risks compared to other projects with comparable capacities. The geological conditions are generally favourable and the river flows are based on gauging stations with the longest continuous records in Nepal. The salient features of the project, based on the current findings of the feasibility study can be summarized as follows: a 7 km long reservoir covering a total area of some 1.4 km2. a spillway with a discharge capacity of 8,100 m3/s (corresponding to the 1-in-10,000-yr flood), having a total length of 120 m and a maximum height of 30 m above the foundation level. a desanding basin, 100 m in total width and 300 m long (including the intake works) capable of removing particles to a minimum size of 0.20 mm. a 9.5 m diameter diversion tunnel, 400 m long. an 9.5 m diameter low pressure headrace tunnel, 2.4 km long. an underground powerhouse comprising 5 x 60-MW generating units operating at a net head of 141 m. 100 km of double circuit, 220 kV transmission line from the powerhouse to Nepalgunj, with 208 km of onward transmission line at 220 kV to Butwal (double circuit), and 177 km of 220 kV transmission line from Butwal to Hetauda (single circuit). The project has the capability of peaking for 6 hours a day at 300 MW. The average annual energy potential of the plant is 1874 GWh/yr while the hydrologically firm energy is 1605 GWh/yr (based on monthly 90% reliability). In view of the fact that this station will be connected directly to a main distribution centre at the border town of Nepalgunj, there is excellent potential for exporting secondary power to India. However since the Nepal and Indian systems cannot be directly connected, a separate 220kV single circuit transmission line will be required from the site to the Indian border, a total distance of 115 km in order to provide the flexibility to supply both the Nepal and Indian systems. westnepal.wordpress/page/12/
Posted on: Thu, 16 Oct 2014 04:58:18 +0000
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