WATER ALLOCATION

FOR THE DEVELOPMENT AREA

 

Project I of Phase I of the Mahaweli Development Scheme which consists of the Polgolla and Bowatenna diversion domplexes is a run of the river scheme,* and makes full use of the available storages in existing reservoirs in Anuradhapura, Polonnaruwa and Trincomalee districts for regulation of water for assured supply both for existing lands and for new lands to be developed under irriga­tion. The following Table indicates the capacities of these reservoirs and areas proposed to be developed for both existing and new lands under each of these projects

 

Inflows into Major Reservoirs and their Capacities

 

System H & IH

 


                                      Catch-           Av        Max         Min          Net               Farm area in ac

                                         ment     inflows      inflow      inflow   capacity

                                          area     103 ac     103 ac     103 ac     103 ac     stage I    stage II

                                     Sq. mls             ft             ft             ft             ft

Area H

Kandalama  ..       ..               38         25.1         65.2           4.9         23.8       4,000   14,000…

Kalawewa   ..       ..             325       166.4       395.3         57.4         96.8      13,000   57,000…

Maha Illup.  ..       ..                                                                          4.0

Kattiyawa    ..       ..               53         12.3         31.8           2.7           2.6              

Usgala Suyambalan

 Gamuwa     ..       ..               71         41.7         98.7         15.0         20.8       1,500

Rajangana    ..       ..             622       103.4       245.6         35.9         76.6      17,000

Angamuwa  ..       ..               50         33.0         85.7           6.3         10.4              

 

Area IH

Nachchaduwa       ..                ..                                                                     44.0

Nuwara Wewa     ..             275       180.3       468.9         32.4         31.2      10,000

Basawakkulama    ..                                                                          1.9

Tissawewa  ..       ..                                                                          2.9

                                                       562.2     1391.2       154.6       315.0      45,500      71,000

 


                                                                                                                 Stage I   Stage II

Area D & G

Elahera        ..       ..                           8.42         28.5           0.8              -       4,800

Giritale         ..       ..              9.0         5.14         17.2           0.5         17.5       4,400

Minneriya    ..       ..            93.0       50.04       169.5           4.6       110.0      14,325

Kaudulla      ..       ..            32.0       32.52       110.1           6.4       104.0      10,230      12,000

Kantalai       ..       ..            77.0       95.51       299.7           7.8       110.0      22,230       8,000

Parakrama Samudra                 .         28.0         33.0       103.5           2.7         81.0      18,200

                                                     224.63       728.5         22.8       422.5      74,185      20,000

 

…    About 400 of this area will be used lowland paddy and the other 600 for upland crops including paddy

                    

 

The UNDP/FAO/Irrigation Dept. studies for 1964-68 which resulted in the Master Plan for the development of the Mahaweli provided for the development of 122,200 existing acres and 84,500 acres of new land under the Polgolla diversion project. The UNDP proposals provided for a tunnel of 2,000 cusecs capacity at PoIgolIa, and a tunnel of 700 cusecs capacity at Bowatenna. When the Project was taken up for implementation in 1969 the existing acreages under Nachchaduwa and the Anuradhapura city tanks amounting to 10,000 acres was also included in the Project I. Fresh water studies were carried out on the basis of five-day river flows and the computer studies indicated that while the Polgolla tunnel capacity could remain at 2,000 cusecs the Bowatenna tunnel capacity had to be increased to 1,000 cusecs. The original proposals for the Polgolla Diversion Project were