Sikta Irrigation project

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Project Proposal for the Implementation of Sikta Irrigation Project
Project Proposal for the Implementation of Sikta Irrigation Project

Background
The Sikta Irrigation Project is situated in the Banke District of the Mid Western Development Region. The Project, with a cultivable command area 33,766 ha including the rehabilitation of Dunduwa Irrigation system, constructed by Indian Cooperation Mission in 1964, would irrigate almost all the low lands of the Banke District and its economic impact could be significant for this development region. The Project area comprises 34 Village Development Committees (VDCs) and the municipality of Nepalgunj, which is the District head quarter. The irrigated area can be further extended by 9,000 ha of 9 VDCs lying on the left bank of Rapti River.

The concept for the Sikta Irrigation Project was first formulated in pre-feasibility studies conducted from 1975 to 1976 and contained in the report on the proposed Western Rapti Multipurpose Development, which comprised the construction of a high dam at Bhalubang of Dang District with a storage reservoir for irrigation and hydropower development in the West Rapti Basin and adjacent areas such as Kapilvastu.

The German company Lahmeyer International GmbH completed a feasibility study for Sikta Irrigation Project in August 1980 based on a run-of-the-river diversion gravity irrigation scheme. A further study for a run-of-the-river scheme was carried out by the then Department of Irrigation, Hydrology and Meteorology and this was completed in June 1983. However, due to unavailability of external funding, the project could not be developed until 2002, when Irrigation Development Project – MWR decided to reassess the project. In April 2004, the feasibility study report was submitted by the IDP-MWR after having a rigorous field level study. The study showed that the project is technically, economically and socially viable in the present context as well. Based on the Feasibility Study Report 2004, the Government of Nepal decided to implement the Project in three phases, which are as follows. The total cost of the Project as per the Study is NRs 7.45 billion (revised to NRs 12.80 billion in Fiscal Year 2007/08).

Phase I – Construction of Headworks and Desilting Basin

Phase II – Construction of Main Canal and Branch Canals 

Phase II – Command Area Development

In view of the relatively high incidence of rural poverty in Banke District in the Mid Western Development Region – 40 percent of the rural households fall below the poverty line -, the small number of existing irrigation facilities and the limited local surface and groundwater resources in the district which would be suitable for small or medium scale irrigation development, Government of Nepal (GON) has therefore given a high priority to the implementation of the large scale Sikta Irrigation Project which would irrigate about 43,000 ha of land (including the proposed extension on the left bank) in the District. The water source for this project is the West Rapti River, which originates from the mid-mountains in the Mid Western Region of the country, having average annual flow of about 120 m3/s.

The overall goal of the Sikta project is to contribute to the National Development Objectives of GON and to improve the standard of living of the people in Banke District. This would be achieved by the provision of irrigation facilities together with the improvement of agricultural support services, which would improve the agricultural productivity so that agricultural production and thus incomes of the rural population would be increased.

Project Area 
The Project Area is located in the Banke district of the Mid Western Development Region of Nepal. It covers 34 Village Development Committes and one Municipality of the District. Nepalgunj is the headquarter of Banke district and although the administrative head quarter of the Mid Western Development Region is Birendra Nagar in the Surkhet District, Nepalgunj remains the commercial centre of this Region. The Project area is enclosed by the East-West Highway (Mahendra Rajmarg) to the North, the national boundary to the South, Dang District in East and Mankhola to the West. Geographically the area comprises lands between 280 00\\\\\\\\\\\\\\\’ and 810 14\\\\\\\\\\\\\\\’ N latitudes and 810 32\\\\\\\\\\\\\\\’ and 810 57\\\\\\\\\\\\\\\’ E longitudes A location map of the project area is shown in Figure 1.

The headworks under construction lies within 300 m of the highway at the Agaiya village about 58 km east of Nepalgunj. The project area is accessible by the national highway (Mahendra Rajmarg) by road. The district headquarters of Nepalgunj is connected from Kohalpur with the national highway by a regional highway which continues up to the Nepal-Indian Border crossing at Rupaidhiya. 

Nepalgunj has all weather airport having daily flights from Kathmandu. This airport is a hub for most of the air service to the remote hill districts in the Mid Western Development Region. 

Water Resources
Of all the streams and rivers in the District, the West Rapti river, although rain-fed, is the only river with a significant perennial flow during the dry season and is therefore proposed as source for the irrigation system. The drainage area of the Rapti River lies in the Mid Western Region of Nepal between elevations of 140 to 4000 m asl. The total length of the river to the proposed diversion site as about 280 km, and the catchment area covers 5,459 km2 at this diversion site. The Rapti river is formed by the confluence of two main rivers in the Mid-Western hill region, the Madi khola and the Jimruk khola, the more important being the Madi Khola which has two tributaries; the Lungri and Arung kholas.

The Rapti river has been gauged since 1964. The nearest gauging station to the proposed diversion site is at Jalkundi about 42 km upstream from the site with the catchment area of 5,150 km2. This station has hydrological records since 1964. In the absence of long term gauging at the intake site selected for the Project, the hydrological analysis is based on the records of Jalkundi. 

The mean monthly discharge, median monthly discharge and 80 % reliable flow for Rapti River at Jalkundi is presented in Table 3-3.

Table 3 1: Monthly Discharge of West Rapti River at Jalkundi

Discharge in m 3/s

Month Jan Feb. March April May June July Aug. Sept Oct Nov Dec
Mean monthly discharge 32.4 27.4 22.4 17.6 19.5 112 333 451 370 149 61.7 39.8
Median monthly discharge 28.1 24.8 19.8 14.4 10.8 64.7 251 380 291 120 52 34.1
80 % Reliable discharge 24.8 20.8 16.7 12.5 8.56 50.4 212 348 233 94.4 42.8 30.7

The Irrigation Infrastructure
To provide irrigation water to 33,766 ha of Banke District, the Project would construct a run-of-the-river, gravity irrigation system, which would comprise the following principal works.

  • A barrage with a total length of 317 m across the Rapti adjacent to the Agaiya village on the East West Highway, backing up the river flow to a sufficient elevation to command 33,766 ha.
  • An intake head regulator is designed for a maximum diversion capacity of 62.5 cumecs, 50 cumecs for the right bank main feeder canal and 12.5 cumecs for flushing from the settling basin. The canal intake structure with two gated openings and a two chamber desilting basin.
  • A canal head regulator on the left side will be provided for the diversion of water to irrigate 1,800 ha, the command area of Rajkulo Irrigation Project.
  • A lined feeder canal section of the main canal with a maximum discharge capacity of 50 cumecs, about 50 km parallel to East-West Highway to serve the main cultivable command area 33,766 ha on the right bank of the Rapti. The canal will have a total of 91 structures out of which 66 are minor and 25 are major. The structures comprise of siphons, aqueducts, highway crossings, village road bridges and covered canals. The canal will be flanked along its length by an all-weather inspection road. The feeder canal will enter the command area about 2 km. south of Kohalpur.
  • A main canal (50 km) and secondary, sub-secondary canals (233 km) delivering water to 85 ha blocks in the command area, flanked by all weather inspection roads and provided with appropriate control, measurement and auxiliary features.
  • An open drainage system will be developed starting from the field channel to collector drain and subsequently connected to tertiary, secondary and primary drains. No salinity symptoms in land irrigated from tube wells or from existing surface lifting systems are observed.
  • River bank protection works will be provided to control the erosion along the Rapti and Dunduwa rivers.

The Project would incorporate the existing ground water irrigation facilities and the two existing surface lift irrigation systems in the water distribution system to allow a structures conjunctive use of the irrigation facilities. Since the discharge in the Rapti River would only allow to start diversion for the monsoon crop in the main command area in the middle of June , therefore the existing groundwater facilities would be very important for the establishment of nurseries for paddy cultivation. 

The above infrastructure development works do not include the infrastructures to be developed on the left bank for 9,000 ha. The works on the left side will be planned after conducting a feasibility level study, which will be carried out in the F/Y 2008/2009. 

Development Plan
The Project would construct a run-of-the-river, gravity irrigation system, which would comprise the following principal works to be implemented in three phases.

The Figure 2 shows the Project Development Plan, which has been divided in the three Phases and various steps within the phases. As shown in Figure 3, the project will be implemented in three Phases as given below.

Phase 1 – Construction of Headworks

Phase 2 – Construction of Main Canal and Branch Canals

Phase 3 – Command Area Development Works

Phasewise breakdown of the works in each of the Phases is given below.

Phase I : Step 1: Civil Works for Headworks Construction
Step 2: Electromechanical part of Headworks
Phase II : Part 1: Main canal from Ch 0+614 to Ch 15+000
Part 2:
Step 1: Main canal from Ch 15+000 to 35+000 Km.
Step 2: Branch (Secondary) Canals

  • Sidaniya Branch (16 km)
    Offtaking point: Ch 28+000 Km of Main canal
    Command area: 1,711 ha.
  • Dunduwa Branch 19.00 Km
    Offtaking point: Ch 32+900 Km of Main canal
    Command area : 16,780 ha.
  • Akalgharwa Branch (5.30 km)
    Offtaking point: Ch 34+800 Km of Main canal
    Command area : 905 ha.

Step 3: Sub secondaries and tertiaries of above Branch canals.
Part 3:
Step 1: Main canal Chainage 35+000 to Ch 50+000 Km. (upto Manpur river)
Step 2: Branch (Secondary) Canals

  • Gohawa Branch (3.00 km)
    Offtaking point: Ch 36+400 Km of Main canal
    Command area : 229 ha.
  • Parsenipur Branch (11.00 km)
    Offtaking point: Ch 37+300 Km of Main canal
    Command area : 1,328 ha.
  • Pirari Branch (3.50 km)
    Offtaking point: Ch 38+900 Km of Main canal
    Command area : 1,310 ha.
  • Guruwagau Branch (18.00 km)
    Offtaking point: Ch 40+700 Km of Main canal
    Command area : 8,129 ha.

Step 3: Sub-secondary and tertiary of above Branch Canals

Phase III : Command Area Development works

Present Status Of The Project

Institutional Set Up
The Department of Irrigation under the Ministry of Water Resources is the responsible organization to implement the Project. The DOI has already established a Project Office, namely Sikta Irrigation Project (SIP), at Nepalgunj, the district headquarters and deputed nine professional staff and adequate number of supporting staff for the execution of the Project. The SIP has already started the implementation of Phase 1 works.

Phase 1 Works
The SIP has contracted out the Construction of Headworks to SINOHYDRO-LUMBINI Joint Venture in June 5, 2006 through an International Competitive Bidding. The contract amount is NRs 1.85 Billion. The works included in the contracts are given below.

  • Construction of 317 m long diversion structure across Rapti River at Agaiya, Banke
  • Construction of head regulators on the both sides of the river
  • Construction of desilting basin of 650 m length on the right bank (62.5 m3/s capacity)
  • Construction of guide bank (about 700 m)

The Construction of headworks has already been started from Novermber 1, 2006. It has been planned to complete nearly one third of the headworks construction within the current Fiscal Year 2063/64 (July 15, 2007). The total construction period for the construction works under the contract is 42 months, which ends in December 31, 2009.

Phase 2 Works
For the construction of Main Canal from Chaiange 0+614 to 12+036, selection of the Contractor is in process and the Contract will be awarded within January 2009. Three contracts have been awarded to the local contractor for the construction of the Main Canal from Chainage 12+036 to 15+000 km.

Month Jan Feb. March April May June July Aug. Sept Oct Nov Dec
Mean monthly discharge 32.4 27.4 22.4 17.6 19.5 112 333 451 370 149 61.7 39.8
Median monthly discharge 28.1 24.8 19.8 14.4 10.8 64.7 251 380 291 120 52 34.1
80 % Reliable discharge 24.8 20.8 16.7 12.5 8.56 50.4 212 348 233 94.4 42.8 30.7

The Irrigation Infrastructure
To provide irrigation water to 33,766 ha of Banke District, the Project would construct a run-of-the-river, gravity irrigation system, which would comprise the following principal works.

  • A barrage with a total length of 317 m across the Rapti adjacent to the Agaiya village on the East West Highway, backing up the river flow to a sufficient elevation to command 33,766 ha.
  • An intake head regulator is designed for a maximum diversion capacity of 62.5 cumecs, 50 cumecs for the right bank main feeder canal and 12.5 cumecs for flushing from the settling basin. The canal intake structure with two gated openings and a two chamber desilting basin.
  • A canal head regulator on the left side will be provided for the diversion of water to irrigate 1,800 ha, the command area of Rajkulo Irrigation Project.
  • A lined feeder canal section of the main canal with a maximum discharge capacity of 50 cumecs, about 50 km parallel to East-West Highway to serve the main cultivable command area 33,766 ha on the right bank of the Rapti. The canal will have a total of 91 structures out of which 66 are minor and 25 are major. The structures comprise of siphons, aqueducts, highway crossings, village road bridges and covered canals. The canal will be flanked along its length by an all-weather inspection road. The feeder canal will enter the command area about 2 km. south of Kohalpur.
  • A main canal (50 km) and secondary, sub-secondary canals (233 km) delivering water to 85 ha blocks in the command area, flanked by all weather inspection roads and provided with appropriate control, measurement and auxiliary features.
  • An open drainage system will be developed starting from the field channel to collector drain and subsequently connected to tertiary, secondary and primary drains. No salinity symptoms in land irrigated from tube wells or from existing surface lifting systems are observed.
  • River bank protection works will be provided to control the erosion along the Rapti and Dunduwa rivers.

The Project would incorporate the existing ground water irrigation facilities and the two existing surface lift irrigation systems in the water distribution system to allow a structures conjunctive use of the irrigation facilities. Since the discharge in the Rapti River would only allow to start diversion for the monsoon crop in the main command area in the middle of June , therefore the existing groundwater facilities would be very important for the establishment of nurseries for paddy cultivation. 

The above infrastructure development works do not include the infrastructures to be developed on the left bank for 9,000 ha. The works on the left side will be planned after conducting a feasibility level study, which will be carried out in the F/Y 2008/2009. 

Development Plan
The Project would construct a run-of-the-river, gravity irrigation system, which would comprise the following principal works to be implemented in three phases.

The Figure 2 shows the Project Development Plan, which has been divided in the three Phases and various steps within the phases. As shown in Figure 3, the project will be implemented in three Phases as given below.

Phase 1 – Construction of Headworks

Phase 2 – Construction of Main Canal and Branch Canals

Phase 3 – Command Area Development Works

Phasewise breakdown of the works in each of the Phases is given below.

Phase I : Step 1: Civil Works for Headworks Construction
Step 2: Electromechanical part of Headworks
Phase II : Part 1: Main canal from Ch 0+614 to Ch 15+000
Part 2:
Step 1: Main canal from Ch 15+000 to 35+000 Km.
Step 2: Branch (Secondary) Canals

  • Sidaniya Branch (16 km)
    Offtaking point: Ch 28+000 Km of Main canal
    Command area: 1,711 ha.
  • Dunduwa Branch 19.00 Km
    Offtaking point: Ch 32+900 Km of Main canal
    Command area : 16,780 ha.
  • Akalgharwa Branch (5.30 km)
    Offtaking point: Ch 34+800 Km of Main canal
    Command area : 905 ha.

Step 3: Sub secondaries and tertiaries of above Branch canals.
Part 3:
Step 1: Main canal Chainage 35+000 to Ch 50+000 Km. (upto Manpur river)
Step 2: Branch (Secondary) Canals

  • Gohawa Branch (3.00 km)
    Offtaking point: Ch 36+400 Km of Main canal
    Command area : 229 ha.
  • Parsenipur Branch (11.00 km)
    Offtaking point: Ch 37+300 Km of Main canal
    Command area : 1,328 ha.
  • Pirari Branch (3.50 km)
    Offtaking point: Ch 38+900 Km of Main canal
    Command area : 1,310 ha.
  • Guruwagau Branch (18.00 km)
    Offtaking point: Ch 40+700 Km of Main canal
    Command area : 8,129 ha.

Step 3: Sub-secondary and tertiary of above Branch Canals

Phase III : Command Area Development works

Present Status Of The Project

Institutional Set Up
The Department of Irrigation under the Ministry of Water Resources is the responsible organization to implement the Project. The DOI has already established a Project Office, namely Sikta Irrigation Project (SIP), at Nepalgunj, the district headquarters and deputed nine professional staff and adequate number of supporting staff for the execution of the Project. The SIP has already started the implementation of Phase 1 works.

Phase 1 Works
The SIP has contracted out the Construction of Headworks to SINOHYDRO-LUMBINI Joint Venture in June 5, 2006 through an International Competitive Bidding. The contract amount is NRs 1.85 Billion. The works included in the contracts are given below.

  • Construction of 317 m long diversion structure across Rapti River at Agaiya, Banke
  • Construction of head regulators on the both sides of the river
  • Construction of desilting basin of 650 m length on the right bank (62.5 m3/s capacity)
  • Construction of guide bank (about 700 m)

The Construction of headworks has already been started from Novermber 1, 2006. It has been planned to complete nearly one third of the headworks construction within the current Fiscal Year 2063/64 (July 15, 2007). The total construction period for the construction works under the contract is 42 months, which ends in December 31, 2009.

Phase 2 Works
For the construction of Main Canal from Chaiange 0+614 to 12+036, selection of the Contractor is in process and the Contract will be awarded within January 2009. Three contracts have been awarded to the local contractor for the construction of the Main Canal from Chainage 12+036 to 15+000 km.