|Project Rationale and Linkage to Country/Regional Strategy
At the national level, Sri Lanka has abundant access to water resources with about 50,000 million cubic meters (MCM) of annual runoff and an annual per capita endowment (ACE) of 2,500 cubic meters (m3), well above the 1,700 m3 threshold defining water stress. However, there are significant spatial and temporal variations; the northern dry zone river basins contribute only about 11% of the country's total runoff volume and only during the December to February period. This amounts to a local ACE of 1,200 m3 indicating severe water stress which is compounded by regular droughts. Consequently, agricultural productivity in this region lags behind other wetter regions in Sri Lanka with 25% to 30% lower paddy yields and cropping intensities. This stress also impacts water availability for drinking and commercial users. This causes significant constraints for social and economic development which may be exacerbated in the future by anticipated population growth and climate change.
Historically, Sri Lanka has addressed these constraints by constructing many small cascade systems of reservoirs and transfer canals. In the 1960s, under MDP, the government decided to augment water within these systems with available water resources in the MRB using large transfer canals and reservoirs. The MRB is Sri Lanka's largest river basin, comprising 18% of Sri Lanka's area and providing 21% of the country's overall runoff. Over time, the government has revised MDP accounting for socio-economic changes and national development priorities. The government's current priorities and investment roadmap are described in the Mahinda Chintana for the irrigation and water resources sector. These focus on ensuring availability of adequate water quantities for irrigation; improving management, productivity and usage efficiency of water to meet rising demands; and minimizing spatial variations in water availability through implementing trans-basin diversions to divert available water to dry zone areas. The updated MDP will address the government's sector priorities constructing the North Central Province Canal Program (NCPCP), an outstanding investment component of MDP. NCPCP will be implemented in two sequential phases: Phase 1 will transfer water from MRB to existing reservoirs in the Central, North Central and North Western Provinces; and Phase 2 will extend the transfer of MRB water from the North Central Province reservoirs to existing reservoirs in Northern Province, and will eventually augment drinking water supplies to Jaffna and Kilinochchi. The investment program will implement Phase 1, comprising four investment projects:
(i) The Kaluganga-Moragahakanda Transfer Canal (KMTC) will convey up to 771 MCM of water annually between Kaluganga and Moragahakanda Reservoirs, both of which are under construction. The reservoirs will retain local runoff and Mahaweli River flow diversions before commanding downstream irrigation and water supply schemes. The length of the canal is 9 kilometers (km) and comprises about 8 km of tunneling.
(ii) The Upper Elahera Canal (UEC) will annually convey up to 974 MCM northwards from Moragahakanda Reservoir, along a 70 km canal (including about 20km of tunnels and 16 km of cut-cover conduits), to the existing Huruluwewa and Mannakattiya Reservoirs, which feed existing irrigation and water supply schemes.
(iii) The North Western Province Canal (NWPC) will annually withdraw 130 MCM from Dambulu Oya River and the existing Nalanda Reservoir to command new and existing irrigation and water supply reservoirs located throughout North Western Province via 80 km of new and upgraded canals including a new 700 meter (m) tunnel.
(iv) Minipe Left Bank Canal Rehabilitation (MLBCR), located downstream of the Mahaweli Hydro Power Complex on the Mahaweli River, will: (a) add upstream storage by heightening the headwork's weir by four meters to regulate generation inflows, and (b) rehabilitate the 76 km Minipe Left Bank Canal to improve conveyance and reliability of service to existing farmers.