Om Power Company Pvt.Ltd.

1. DESCRIPTION OF PROJECT AREA

1. Location

Thuligad Khola Hydropower Project is a run-of-the-river type scheme located at Badikedar Gaupalika of Doti district in Sudurpashchim Province of Nepal. Headworks area of proposed project is located at about 1000 m upstream from confluence of Beworeni Khola with Thuligad Khola. Approximate aerial distances of powerhouse and headworks of proposed project from BP Nagar Bazaar, the nearest Bazaar from the project area, 12 and 7.5 km respectively.

The project facilities such as intake, settling basin, water conduit system, surge shaft, penstock and powerhouse are located on the left bank. Geographically the project area lies between the latitudes of 28° 55’ 50” to 28° 58’ 47” N and the longitudes of 80° 47’ 41” E to 80° 51’ 22” E.

Project area is located between 700 m and 500 m above mean sea level in the middle reach of Thuligad Khola located at Badikedar Gaupalika of Doti district. It takes 10 hours to reach the proposed headworks site; 1.15 hours flight from Kathmandu to Dhangadi, 60 km black topped road drive from Atteria to Sahajpur, 3 hours and 20 km earthen road drive from Sahajpur to BP Nagar. From BP Nagar, local government opened the track towards the proposed headworks site which requires upgrading for project use.

2. Physical Features

Physiographically, the project area belongs to the Siwalik Mountains and Middle Mountains, while the upper catchment of the Thuligad Khola extends to Middle Mountains. Thuligad Khola is one of the tributaries of the Karnali River. Thuligad River is a spring source river originating from an altitude of about 2500 m and flows west to east.

The elevation within the basin varies from 600 m to 1600 m with an average basin elevation of 1100 masl. The catchment area at the proposed dam site is 640 sq. km and lies entirely below 3000 m elevation.

Mountains are characterized by steep to medium slopes depending on elevation. Mixed forests occur between elevations of 1500 m to 2500 m and transition to subtropical forests below 2000 m. Cultivation is practiced up to an altitude of 1800 m.

The average gradient of the river in the project reach is about 10% and the river width varies from 50 m to 100 m. The discharge diminishes gradually as tributaries are left behind.

Topographical features of the project area are favorable for hydropower construction. The headworks site lies on stable river banks while the powerhouse site lies on barren land on the left bank. A concrete diversion weir is proposed to divert water into the conveyance system. The project utilizes a design discharge of 11.662 m³/s and a gross head of 173.50 m.

About 60% of the catchment is covered by thin mixed forest, while the remaining area consists of barren land, grassland with scattered vegetation, and agricultural land. No major streams cross the headrace tunnel or penstock alignment. The powerhouse is located upstream of the confluence of Lakhan Khola with Thuligad Khola.

Population density is very low and dominated by Chhetry population with small numbers of Kami and Brahmin communities. No religious or historical sites were observed to be affected. Telephone network coverage is available. The main occupation of the local population is small-scale agriculture and livestock rearing. The nearest market center is BP Nagar.

2. ACCESSIBILITY

Several road networks in and around the project area are under construction. The project is best accessed from Dhangadi via Mahakali Highway to Sahajpur which will be used for heavy transportation. BP Nagar, the nearest bazaar, is accessed from Sahajpur. A project road from BP Nagar to the headworks site requires upgrading.

SN	Location	Road / Type	Distance (km)
1	Dhangadi – Sahajpur	Mahakali Highway / Blacktopped	61.2
2	Sahajpur – BP Nagar	Earthen Road	20.5
3	BP Nagar – Headworks	To be upgraded by project	7.5

3. INFRASTRUCTURE FACILITIES

Infrastructure facilities at the project site are satisfactory for construction activities. BP Nagar is electrified by NEA. At Kharhar village near the powerhouse site, electricity from a local micro-hydro project is available and can be extended to the project area.

Both powerhouse and intake sites have telephone communication through wireless CDMA and SKY phones. Road access near the powerhouse site exists but requires upgrading and maintenance. The proposed headworks site can be accessed by constructing approximately four kilometers of project road along the pipe alignment.

A 33 kV BP Nagar substation has already been completed. Energy generated from the project will be evacuated to INPS through this substation via a 12.25 km long double circuit 33 kV transmission line.

4. FIELD INVESTIGATION AND DATA COLLECTION

4. Topographical Survey and Mapping

The methodology adopted for the topographical survey of the Thuligad Khola Hydropower Project is described in this section. Detailed drawings are presented in Volume II.

Objectives and Scope

• Preparation of detailed topographic maps for all project components
• Survey of approximately 30 ha project area at scale 1:10,000 with 1 m contour interval
• Headworks area survey at scale 1:500
• Strip survey of water conveyance route at scale 1:1000
• Powerhouse, surge shaft, penstock and tailrace survey
• Transmission line walkover survey
• River longitudinal profile and cross-section surveys

Available Maps

• Topographical maps (Scale 1:50,000) by Department of Survey, Nepal
• District map of Doti (Scale 1:125,000)
• Project layout plans and digital data

Surveying

Prior to the field survey, a desk study was carried out using available topographic maps. A reconnaissance survey was conducted and control points were established from third-order national grid control points. A total of nine permanent benchmarks were established across the project area.

Station	Northing	Easting	Elevation (m)
BM1	3055364.842	461051.759	2895.285
BM2	3055422.959	460916.860	2913.821

5. GEOLOGICAL AND GEOTECHNICAL STUDIES

Thuligad Khola is a tributary of the Karnali River with reliable discharge. The project area lies about 11.5 km east of BP Nagar. All major project structures are located on the left bank of Thuligad Khola.

The major structures include a diversion weir, headrace tunnel, surge shaft, penstock pipe and powerhouse. The elevation difference between weir and powerhouse is approximately 173.5 m.

Field investigations were carried out in December 2017 focusing on geological and geotechnical conditions and construction material availability. Rock and soil types, geological boundaries, and discontinuities were studied. Geological maps were prepared and conclusions are presented in this chapter.