The Giant Mahaweli Projects Sri Lanka

 



Reservoirs, Weirs Nourishing Mahaweli

The Mahaweli River System is Sri Lanka's main River system. The River is 331 kilometers long. The Mahaweli construction project was Sri Lanka's largest infrastructure project at the time. The Mahaweli River Development Plan proposes to use the River for both hydropower generation and irrigation in Sri Lanka's dry region. However, the majority of people believe it begins with 'Sri Pada', The Mahaweli River, which originates in 'Horton Plains', is Sri Lanka's longest River. There are 14 reservoirs nourishing from Mahaweli River including acrossed weirs by its 335 kilometers of journey.

Kothmale, Polgolla, Victoria, Randenigala, Rantembe, Minipe old and new weirs, Loggaloya, Hippolaoya, Diyabanaoya, Ulhitiya, Rathkinda, Maduruoya and Sorabora wewa are the fourteen reservoirs. The River joins to the sea in 'Koddiyar' beach over 'Gange' area. There are also several sub-Rivers that flow into the Mahaweli River.

  

Sub Rivers maintaining from Mahaweli

Sub River             Point meeting Mahaweli River

Dambagasthala Oya        N/A

Pundalu Oya      N/A

Puna Oya             Kothmale

Hattano River    Mahawillewa

Atabage Oya      N/A

Nilambe Oya      N/A

Hungan Oya       Peradeniya

Pinga Oya            Katugastota

Mailapitiya Oya N/A

Maha Oya           N/A

Belihul Oya         N/A

Kurundu Oya     N/A

Uma Oya             Rantembe

Amban Ganga (Sudu Ganga + Nalanda Oya + Kalu Ganga)             N/A

 

Kothmale Reservoir

Between the mountains of 'Thispane' and 'Kadadora', the Kothmale dam was built. The dam has a length of 600 meters and a height of 87 meters. The construction phase began on February 4, 1979, and ended on August 24, 1985, with the opening ceremony taking place on August 24, 1985. The Mahaweli River nourishes this reservoir, which is the highest from sea level. This reservoir provides several economic and agricultural benefits and purposes. One of the key functions of the reservoir is to serve as a safe haven for the town of 'Gampola'. Because of the Mahaveli River's flood, the 'Gampola' town is flooded. The historical and ancient villages of Maswela, Kadadora, Thispane, Pallegammana, Marape, Mawela, and Urugampelessa were closed to the reservoir in 1979.

After 05 kilometers from the reservoir the Hatton River meets the Mahaweli River in 'Atabage'. And 18 kilometers from the reservoir rejoining the reservoir's water tunnel, which was used to produce electricity at the Kothmale Electricity plant.


Kothmale Electricity Plant

The Kothmale underground electricity plant is located 225 meters below ground level in 'Atabage'. It has a tunnel that runs from the Kothmale reservoir to the entrance. The tunnel has a direct length of 07 kilometers and a diameter of 6.2 meters when it first opens. The tunnel's diameter is steadily decreasing until it reaches 2.8 meters at the end. This generates 201kW of electricity from three turbines, each of which generates 67kW.

The generated electricity is transported by cables from the plant to the transmission station at the summit of the mountain. Two electricity cables go to Colombo and one cable goes to Anuradhapura from the transmission station. The building project was a Swedish government project that lasted from 1979 to 1985 August. The project was expected to cost 11 billion rupees.

This is Sri Lanka's second-highest electricity factory.


Polgolla Dam

The length of the barrage is 144 meters and the height is 14.6 meters. The barrage's aim is to increase the water level towards the tunnel. Therefore, the main goal of this project is to provide water to Rajarata, including Ukuwela, in order to generate electricity and for agricultural purposes. There is a tunnel running from here to the Rajarata region across the mountain called 'Pathadumbara'. In Polgolla, the tunnel starts 20 feet below ground level and has a diameter of 19.5 feet. The tunnel is eight kilometers long. It delivers 12500 square feet of water per second through the Ukuwela power plant in Rajarata region. This tunnel is used to produce 40 megawatts of electricity at the Ukuwela power plant in Ukuwela.

This is the Mahaweli project's very first weir.


 

Victoria Reservoir

The Victoria dam was built between the mountains of 'Deniyagala' and 'Bolagala,' also known as 'Bathalagala'. With a length of 520 meters, a height of 122 meters, and a thickness of 25 meters, this is Sri Lanka's tallest dam. The dam was constructed after a 125-mile journey that began with the Mahaweli River. 'Hulunganga' joins the Mahaweli River in this area before the dam was built. The ancient villages of Theldeniya, Aluthwela, Udaberiya, and Pooragala were forced to close due to the reservoir.

The dam's primary functions are agricultural and electric power generation. The project began on March 3rd, 1980, and ended on April 12th, 1985. Ms.Magrat Thatcher was the chief guest at the opening ceremony. This was a collaborative project involving Sri Lankan Engineering Corporation and British engineering collaboration. Sir Alexander Gibb & Partners, a British firm, was the contractor. The dam's spill level is 88 meters. The Mahaweli River was dammed from Victoria, and after generating electricity at the Victoria power station, the Mahaweli River began flowing again in 'Hakuruthale,' approximately 6 kilometers away from the dam.

 

Randenigala Reservoir

Randenigala dam was constructed between the mountains of 'Weddandamanaya' and 'Randenigala.'. The dam construction project lasted from 1982 to 1986. The dam is located 19 kilometers away from Victoria dam and 2.8 kilometers upstream of Rantembe dam. The dam has a length of 485 meters and a height of 94 meters. It consists of three spillways with a total discharging volume of 8100 square meters per second. Randenigala Power Station is located in left bank of the River downstream from the dam.

It has two separate turbines each carrying 63 MW and generates 126 MW. Water is transported from the reservoir to the power station through a tunnel which has 270 meters of length and 6.2 meters of diameter. The 12 MW of generated electricity, which is then transmitted through cables to the Kothmale Transmission Station.

 

Rantembe Reservoir

The dam has a length of 420 meters and a height of 41.5 meters above ground level. Construction of the dam began in 1987 and finished in 1990. The dam has four spillways with discharge volume as 10235 cubic meters per second. This produces 50 megawatts of electricity.

The area encompassing the three reservoirs of Victoria, Randenigala, and Rantembe is known as Dumbara Mitiyawatha

The 46-mile-long Uma Oya, which originates in the Thotupola and Pidiruthalagala mountains, joins the Mahaweli River before meeting Rantembe dam. From the right Riverbank, Uma Oya joins the Mahaweli River. From the left Riverbank, Ma Oya joins to the Mahaweli River. 

This is the Mahaweli project's final reservoir and the smallest dam.


Minipe Old Weir

This tells a great deal about Sri Lanka's historical and irrigational importance. The oldest weir along the Mahaweli River is Minipe old weir. According to the Mahawansa, King Dhatusena began construction on Minipe weir. However, history claims that king I Agbo (1st Agbo, A.D.540 - A.D.604) created this weir. This is clear by the most accurate evidence found in that region. The Minipe canal runs parallel to the Mahaweli River on the left bank. King 1st Agbo formed another weir in the Minipe canal, near the confluence of the Minipe and Mahaweli Rivers. As a result, the 'Rajarata', 'Hasalaka' and 'Wasgamuwa' areas are fertilized by the Minipe canal.



Minipe New Weir

After the reformation of the Minipe old weir in 1932 by Hon. D.S.Senanayaka, Minipe new weir was built. In 1984, Hon. Gamini Dissanayake began the new project. The new project in Minipe was to build a new weir as well as the right canal project. The project began on 8th of January in 1978, and ended in 1984.

The new dam measures 225 meters in length and nine meters in height. The right canal water fertilizes the 'Ulhitiya' and 'Rathkinda' areas before reaching the 'Maduruoya' Reservoir. The canal is 32 kilometers long and feeds 72000 acres of land in the 'Mahaweli C' area.

 

Loggaloya Reservoir

Loggaloya Reservoir will be reached by going through the right-bank canal starting from the Minipe. Loggaloya used to be directly connected to the Mahaweli River in 'Madaoya' area. After that, in the 'Madaoya' sector, a dam was built across the loggaloya. Loggaloya is 28 miles long, beginning in the Namunukula, Lunugala, and Madolsima areas. That dam is near the Minipe-Aralaganwila main road.

This dam is unlike any other. This dam has a zigzag shape and a total length of 151 feet. The water from this reservoir is flowing into the 'Ulhitiya' and 'Rathkinda' regions. Only the spill water joins the Mahaweli River in the 'Madaoya' region after the reservoir was created.


Maduruoya Reservoir

The dam was built between the Kandegama and Daanagala mountains. This water is delivered to the Ulhitiya and Rathkinda reservoirs from a rightbank canal in Minipe. Following that, water from the Ulhitiya and Rathkinda reservoirs is fed into the Maduruoya reservoir. Maduru oya is also connected to the Maduruoya reservoir

The dam construction project began in 1978 and finished on February 14th, 1982. The contractor was a Canadian company. The dam has a length of 1090 meters and a height of 41 meters.

 

Sorabora Lake

According to the historical articles, Sorabora Lake was built by a stranger named Bulatha. He was the one who provided ‘Betel’ and milk to King Dutugemunu. He created the lake with the help of his wife while on duty. There is a rock in here that is working as a spillway of the lake. The Rightbank canal, started from Minipe, is now supplying water to the Sorabora Lake.

  

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