IV PHASING
OF THE MASTER PLAN
4.1
Criteria
for phasing
It is estimated that
period of construction required to complete all the work included in the
Master Plan will be about 30 years. As this is a relatively long period.
The Master Plan is split up into three phase consists of a number of projects.
Each project included in the first phase of development is cultivated on
the basis of the following criteria.
a)
It should be capable of development as a separate unit, without
financial commitment to other projects within the phase or in the subsequent
phases.
b)
It should not prejudice subsequent developments.
c)
Its size and nature should be consistent with the ability
of the government to develop the reclaimed land: accordingly priority should
be given for areas where settlement, infra-structure and management do not
present great problems.
d)
It should meet the anticipated expansion in demand for power.
e)
It should be economically viable.
4.2
Project of First Phase of Development
Project No 1: Polgolla
Diversion
(Period of
construction 1969-73)
The head structure
of polgolla with a hydro-electric station of 35.8
megawatts of installed capacity would convey water from the Mahaweli Ganga
to the Sudu Ganga (a
tributary of the Amban Ganga)
though a tunnel. From the upper reaches of the
Amban Ganga part
of the flow would be diverted along the polgolla,
Kala Oya (abbreviated as PK) Canal
to the Kala Oya basin
to irrigate all the existing and 70 percent of the new land in system H.
The last portion of the PK Canal would be in a tunnel. At the end of which
a Hydro-electric station of 3.7 megawatts would be installed. The reminder
of the water would be conveyed to the existing Elahera
Canal
to irrigate the entire area in systems D-1 and G.
The total irrigated
area would be 186 thousand acres of which 84 thousand acres would be newly
irrigated, and the irrigated land would enable valuable experience to be
gained in modern methods of irrigation and crop cultivation. The total installed
capacity at the hydro-electric power stations would be 40 megawatts with
an annual energy production of 200 million kWh. The total cost of Project
I is estimated to reach Rs 576 million.
Project No 2: Victoria
– Minipe Diversion
(Period of
construction 1973-77)
The head structure
(Victoria Dam) on the Mahaweli Ganga with the
hydro-electric station of 120 megawatts of installed capacity. Would feed,
to the new right-bank (RB) canal and the existing Minipe
canal (both of which start at the existing diversion structure at Minipe) a total irrigated area of 88,000 acres of which 74,000
acres are new lands and 14,000 acres come under in proved irrigation.
Firm energy productivity would be approximately 470 million kWh per
year. The commissioning Victoria
hydro-electric station would meet the electric power demand expected
by 1976 in addition. The free storage water in the Victoria reservoir would
compensate for the decline in power generation at he Polgolla
station during the dry season and would also allow the irrigation of 116thousand
acres of new land in the second phase of the scheme (When Maduru Oya and Taldena unit are commissioned). It total cost of Project 2
is estimated at Rs. 676 million.
Project No.3: Moragahakanda
Multi Purpose Reservoir
(Period of
Construction 1977-80)
The
regulated discharge of the Moragahakanda head
structure on the Amban Ganga
with a hydro-electrics station of 40 megawatts of installed capacity.
Would provide sufficient water supply for a total of 54,000 acres.
(26,000 newly irrigated and 28,000 under improved irrigation). Firm energy production would be 150 million
k W h per year. The total cost of project 3 is estimated at Rs.
298 million. And it shows the highest unit cost per acre of the projects.
However, a part of the benefits from the project would spill in to the second
phase. Thus, it should be considered as the transitional step between the
first and the second phase of the scheme.
Summary of the First Phase
It is proposed to
irrigate a total of 328,000 acres in the first phase development. Of these,
184,000 acres would come under new irrigation and 140,000 acres of the existing
irrigation systems would be improved. The hydro-electric stations proposed
for construction would have a total installed capacity of about 200 megawatts
and would produce about 820 million k W h of firm energy per year. The total
cost of the first phase projects is estimated at Rs
1,550 million of which Rs. 537 would be required
I foreign exchange and Rs. 1,013 in local currency.
4.3
Subsequent Phases of Development
(a) It is estimated that the second phase
of development will take six years to complete. On the
basis of “free" storage available at Victoria and Moragahakanda,
and with the water release at the newly constructed small hydropower units
of Maduru Oya and Taldena. Having met the water requirements
of the lands of systems A and
B.
The Total irrigated
area would be 230,000 acres (209,000 acres of new irrigation and 21,000
acres of improvement to existing irrigation systems) A small hydro-electric
station at Taldena with in installed capacity
of 15 megawatts would generate 48 million kWh of firm energy for year. The
total cost of the second phase is estimated at Rs.
920 million.
(b) The proposed third phase of development
provides for irrigation of land in the north central part of the Island
and completion of the hydropower development
of the Mahaweli Ganga and its tributaries. Realization
of this phase is planned to take ten years. The Total irrigated area would
be 432,000 acres (261 new and 81,000 improvements to existing system). The
proposed hydro-electric station would have a total installed capacity of
293 megawatts and would produce 1,169 million kWh of farm energy per year.
In the third phase,
the irrigation systems which were previously fed from Moragahakanda
and Victoria would be supplied with water regulated at Randenigala
and Heen Ganga through
the LB (Left Bank
) canal. Certain irrigation systems would be transferred to the regulated
yield from Rotalawela and partly from Randenigala, and others would be supplied mainly from reservoirs
on the Right Bank
tributaries. The Moragahakanda reservoir
augmented with water from the Kotmale reservoir
would be able to supply water through the NCP (North Central Part) Trans
basin canal to system I, J, K, L and M. These transfers would make the operation
of the projects of the first two phases substantially more economical although
the cost of the third phase considered separately appears to be quit high.
The cost of the third
phase is estimated at Rs. 3,113 million. The cost
of development per irrigated acre in the third phase is higher than the
average cost per acre for the scheme as a whole. However with more intensive
land use in the north central part it would be possible to obtain high level
of output per acre.