Uda Walawe
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Looking southwards from Haputale, on a clear day, across the tea covered slopes that plunge beneath one’s feet, an ocean of wild green comes into view, broken only by the glistening water of Hambegamuwa tank. This is the vast undeveloped expanse of wilderness that lies on the left bank of the Walawe Ganga. The Belihul Oya, that cascades down from near ‘world’s end’ is one of the most picturesque headstreams of the Walawe Ganga. Further west is the main Walawe Ganga itself, having its source close to Samanala Kanda hallowed by the footprint of the Buddha. These are the headstreams of the Walawe Ganga, that rise in the well-watered central hill massif of the Island. Four other major streams, the Katupath oya, the Kuda oya, the main river on the right bank, and the Mau ara flows into it on the left bank a few miles below the confluence of the Hulanda oya. The Walawe basin, drained by these and smaller water courses, covers an area of 956 square miles (612,000 acres) The rainfall in the upper reaches of the basin is over 100 inches per year on the average, while at Ambalantota near the river mouth, it is below 40 inches per year. The river discharges 1,100,000 acre feet of water into the sea annually. The development area under the Walawe Basin Project, includes two small areas, extending on the east upto the Malala oya and on the west upto Urubokka oya. The development area in the Walawe Basin has been covered by topographical surveys. Smaller scale mapping done by the Hunting Survey Corporation, cover the Walawe basin.
Uda Walawe Special Area Development The walawe irrigation system in Southern Sri Lanka draws water from the Uda Walawe reservoir on the Walawe Ganga. There are two main canals on the right and left banks respectively, which flow through several smaller tanks on tributaries of the Walawe, and which cotribute to the system’s water resources. The Walawe irrigation Improvement Project area covers some 12,000 ha on the right bank. In January 1982 the Mahaweli Authority of Sri Lanka (MASL) took over the project. MASL introduced measures to improve the overall operation and management of the system. The ADB funded the Walawe Irrigation Improvement Project in 1986. It aims to upgrade and improve the extent and reliability for irrigation supplies through the rehabilitation of the physical infrastructure works and the introduction of improved systematic operating procedures. Meanwhile the left bank with a total area of 30,000 ha was only partly developed. About 5,350 ha have been reclaimed so far in the northern half including sugarcane area, 2,440 ha. but in the southern half thorn scrab land still exists, where unproductive chena cultivation had been practiced on small patches of land. In order to fully utilize facilities provided under the Walawe Project so far, and ease the ever increasing population pressure in the south of the country, the Sri Lanka government (GOSL) decided to further develop the left bank and complete the Uda Walawe scheme as originally planned. In 1987, GOSL requested technical assistance from the Government of Japan (GOJ), in undertaking of a feasibility study on the Walawe Irrigation Upgrading and Extension Project (Left bank). The rehabilitation work of 2,900 ha and irrigation extension work of 1,040 ha in the old area has commenced with financial assistance of OECF Japan as the Stage I project. The detailed design of irrigation extension works of 5,152 ha including basic rural infrastructure has been commenced with financial assistance of OECF in December 1997. In 1993, GOSL requested grant aid from the Japan Government for the implementation of urgently required development components of the formulated Walawe Irrigation Upgrading and Extension project, consisting of i.
Improvement of two rural main roads, 31 km long with asphalt pavement The construction works had been carried out from April 1994 and completed in December 1995. Walawe Left Bank Irrigation Upgrading and Extension Project As at Daily News paper on 17th August 2005-08-18 The fourth and final phase of the massive Rs. 7.5 billion Walawe Left Bank Development (WLBD) Project which aims to create 25,000 new job opportunities will be ceremonially inaugurated on 17th August 2005. The fourth stage of the Walawe Left Bank Development Project costing Rs. 1.1 billion, aims at clearing 1,572 hectares of jungle area for agriculture purposes to settle 2,684 families in this newly developed area. The WLBD project was undertaken under the financial assistance of the Government of Japan through the Japan Bank for International Co-operation. (JABIC) The total area to be developed under the WLBD project is 12,000 hectares, out of which 5,150 hectares will be developed as new agriculture lands. A total of 8,700 families will be settled in the newly developed area of which 5,700 will be farmer families. A special features of the forth and final phase of the project is the promotion of cultivation of vegetable, fruits, banana and other crops instead of paddy. Only 716 hectares have been earmarked for paddy cultivation under this phase while the balance 856 hectares will be cleared for the cultivation of vegetables, fruits and other crops. It is estimated that 22,000 metric tons of paddy, 26,000 metric tons of vegetables and fruits and 19,000 metric tons of banana will be added to the national production with the completion of the WLBD project. Studies reveal that 25,000 new job opportunities will arise with the completion of the WLBD project and approximately 17,000 others will find employment in the agriculture sector. Walawe
Left Bank Irrigation Upgrading and Extension Project The Walawe rive basin covers and area of 2,442 square Km.starting from the central massif of Sri Lanka to the southern coast in Ranna / Hambantota area. Hundred of small irrigation tanks constructed during the ancient times are scattered throughout the Walawe Basin. In early 1960s, the government having decided to develop the Walawe basin for irrigation and hydropower completed a feasibility study based on that, construction of Uda Walawe multi purpose reservoir was completed by the government in 1967 using its own resources. Subsequently, Asian Development bank (ADB) provided two soft loans for the development of irrigation and social infrastructure in the entire right bank area and part of the Left bank area. Meanwhile, the left bank area with a gross extent of 30,000 ha was only partly development bringing the northern half consisting of 5,350 ha that includes sugarcane area of 2,450 ha and 2,900 ha for paddy and other crops under irrigation. But southern part of the Left bank remained undeveloped up to 1993. Subsequently, under JICA grant aid, a main road from Padalangala to Mirijawila and provision of drinking water supply facilities to Sooriyawewa town ere completed in 1996 which was an impetus for further development of southern part of the Left Bank area. As a result, improvement to the irrigation system in the existing area with 2,900 ha and new irrigation facility to 1,100 ha under phase I of the project was completed in 2000 with Japanese assistance. Japan has also provided financial assistance for construction of irrigation and social infrastructure facilities in 5,150 ha of the extension area including rehabilitation of Uda Walawe dam under phase II project which is now in progress. Increase income and improve living standards of farmers of Walawe Left Bank Project by creating environment friendly income generating opportunities and increasing production through efficient and optimum use of land and water resources thereby encourage farmers to take-up commercial agriculture. -
Provide irrigable land for landless, -
Development of 5,150 ha of new irrigable lands Command
Area - 5150 ha
High tanks - 45 Nos. Market Roads - 50.0 km History of the Walawe Development Project Background In 1962, a feasibility study of the Uda walawe reservoir was conducted for the purposes of irrigation development of 32,000 ha in net and settlement of people in the southern dry zone of the country, and hydropower development as well. The Uda Walawe dam was completed in 1967 and water was released in 1968. Initially the system was operated by the River Valleys Development Board (RVDB). The Uda walawe project consists principally of a Reservoir at Uda Walawe, created by a 2 ½ mile long Dam across the Walawe Ganga 3 mile long canal reaching out to Urubokka Oya on the west and a 40 mile long canal extending up to Malala Oya on the east. The Uda Walawe reservoir intercepts 455 square miles of the Walawe Basin yielding 830,000 acre feet of water annually. The maximum depth of the reservoir at full supply is 90 feet, and the water surface area is 7,700 acres. The reservoir will hold 194,000 acre feet of water while the useful storage is 180,000 acre feet. (as Walawe Symposium 1968) Project Cost: Rs. Mn. Dam
- Rs. 60 m (as at Walawe Symposium 1968) Total
Project Cost - $26,455,000 (US $1 = Rs.5.95) (Asian Development Bank (ADB) provided loans for the Walawe Development Project in 1970-1979) and the Walawe Irrigation Improvement Project in 1986-1993.) Between 1972 and 1981 the total area irrigated increased from 3,600 ha to 11,000 ha. During the 1970 through 1980s, priority was given to the development of the Right Bank covering 12,000 ha of irrigable land. Meanwhile, only 4,400 ha have been reclaimed so far in the northern half of the left bank, but the southern half still remains unproductive. Chronological list of events in Uda Walawe basin development Year Event Command Storage 1900s
Construction of Ukgalkaltota Anicut 1930s
Construction of Liyagastota anicut & 5010 27.1 1948
Plans and specifications for Walawe Dam 1960
Reconnaissance survey of the resources of 1960-1962
Design of Uda walawe Reservoir 1964
Completion of Chandrikawewa Reservoir 2020 27 1964
Tendering for dam with alternative dam 1967
Feasibility study of downstream 1968
Completing of Dam 268 1979
Project Completion Report (ADB) 13288 1982
MASL took over the responsibility under 1984
Feasibility study of rehabilitation 1984
Appraisal of Rehabilitation (ADB) 31606 The Uda Walawe reservoir constructed across Walawe Ganga at Uda Walawe has a capacity of 268 million cubic meters (MCM) or 217,800 ac.ft. The irrigated area is fed through two main canals, one on the Right Bank and the other on the Left Bank. These canals flow through several smaller tanks on tributaries of the Walawe basin which also contribute to the overall project water resources. The RBMC is a single banked canal for most of its 40.9 km and therefore collects some direct runoff from the adjacent higher ground. The Right Bank Main Canal empties into Chandrikawewa 17 km below the main reservoir and then takes off through a regular at the southern end to supply water to the balance 24 km of the RBMC. Right Bank Main Canal : The number of farm families is around 10,000. An extent of 9700 ha out of a total of 12,000 ha in the RB system is cultivated at present. The RBMC in Walawe serves Six branch canals and 54 distributary canals which are grouped into five administrative blocks. Left Bank Main Canal : Existing canals serve an area of 6744 ha irrigation area. The design discharge of the Left Bank Main Canal LBMC is 28m3/sec for the entire length of 31 km providing irrigation water to three administrative blocks including the Sevanagala Sugar Corporation area. Approximately 43 km of distributary canals were being supplied by water from the LBMC in 1993. Two medium tanks, Habaralu and Kiriban tanks and several small tanks are interconnected through this canal and supply irrigation water to their own local commands. Proposed Left Bank Extension Area project in 2000 The area of 5152 ha will extend the existing left bank canal to south. Many small tanks with the command area ranges from 10 to 70 ha are distributed within the extension ara, of which 16 tanks are now working condition. Some of those tanks form cascade systems with several tanks connected by natural streams. Upon the completion of the development, supplemental water will be supplied to those tanks from the extended LBMC. Description : Below Command area Farm
Area - 22,350 Above command area Settlement
area - 3,881 Total - 25,003 Grand Total - 55,700 ha Annual Estimated population - 212,883 (as at 2004) Left
Bank Right
bank
Food Crops : Extent Cultivated The main physical components of the project are : Headworks Dam and reservoir – gross storage 555 10 6 m 3 Link tunnel from Mahaweli – capacity – 34 m3/s Share (with System C) of the Minipe right Bank Transbasin Canal in the Mahaweli Valley
Left Bank Canal Right
Bank Canal Tertiary systems, drainage, land levelling, etc Homesteads and settlements Nonirrigation infrastructure.Main and Branch Canal Systems – 248 km 1.
Catchment area 53 sq. km. (175 sq.mls.) 1.
Full supply level 95.5 m (313,32 ft)
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History of the Walawe Development Project Chronological list of events in Uda Walawe basin development Proposed Left Bank Extension Area project in 2000 The main physical components of the project are :
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