EVALUATING THE IMPACT OF LIWONDE BARRAGE

 Since 2011, the country of Malawi has been experiencing low water levels in Lake Malawi but the situation started changing when the country received high amount of rains. To prevent the future uncertainties of drop in the level of water again, Malawi Government and National Water Reserve Authority (NWRA) implemented renovation of Liwonde barrage to control level of water in Lake Malawi. A barrage is a type of dam or barrier constructed across a river to control water flow and flooding. It can also be used to generate hydroelectric power and facilitate irrigation. Barrages have gates that can be opened and closed to regulate the water flow. Recently, water levels in Lake Malawi had increased to 475.39 metres above sea level in March 2023 which was 47.5cm higher than same month of the previous year.

The barrage usually has one or two gates opened to let some water pass through downstream and close the rest of the gates to retain some water upstream in the river and Lake Malawi. It is illegal to close all the gates to stop some water going downstream. Liwonde barrage operate by opening the gates when level of water reaches maximum of 477m above sea level and the water is discharged downstream at a rate of 900m3/second. The barrage assists in storing water in Lake Malawi for future use when levels of water starts dropping. By regulating amount of water going downstream, the barrage helps to reduce the risks of flooding which are common in the lower Shire districts of Chikwawa and Nsanje.

The Liwonde barrage

Recently, people around Mangochi mostly Kalonga and Mwanyama villages have complained that they have been experiencing flooding due to the high accumulation of water in the upper course of Shire river before the Liwonde barrage. Despite not receiving rainfall for about 10 days in April, 2023, water levels in Lake Malawi and Shire river were overflowing into residential houses and hotels. Ironically, those in upper Shire are now being affected by floods as compared to people in the lower Shire. The people blamed the authorities which are overseeing the operation of the Liwonde barrage that they are responsible for the floods as they are closing the barrage gates to keep water upstream of Shire river while letting few amounts of water to pass downstream.

National Water Resources Authority (NWRA) regulates the opening and closing of the barrage. NWRA chairperson James Mambulu outlined that NWRA uses 477 metres above sea level as the maximum height of water and once it is reached, the water is expected to be discharged at 900 cubic metres per second. He therefore outlined that all structures constructed below the recommended 477 meters above sea level in the upstream of Shire river are likely to be affected by submerging of the river even if the water level is not exceeding the required amount. The people in the upper course of Shire river as well as those residing in the borders of Lake Malawi are therefore encouraged to build their houses and hotels not very close to the water body and should be on the height greater than 477 metres above the sea level. By doing this, people will not be affected by flooding until the barrage is to be opened when the maximum level of water of 477m is reached and be discharged downstream to the areas in the Shire valley until Mozambique where the Shire drains into Zambezi river.

Flooding observed in Mangochi in March 2023

The Liwonde barrage is beneficial to some organisations as they draw water from the Shire river for various use. The barrage provides the following volumes of water to various corporations

Company

Volume of water demanded (Cubic metres per second)

EGENCO

300

Mpatamanga HydroPower Plant

180

Shire Valley Transformation Project (SVTP)

50

Illovo Sugar Company

18

Blantyre Water Board

2

Southern Region Water Board

2

(source: Ministry of water and sanitation – Malawi)

One of the programmes which benefit from the Liwonde barrage is the Shire Valley Transformation Programme implemented by ministry of agriculture through the department of irrigation. It was a development plan by the colonial government in the 1940s. The plan was aimed at stabilizing the water levels in Lake Malawi through construction of a barrage at Liwonde, a hydro power station at Nkula and an irrigation scheme in the Shire valley. The first two projects succeeded however construction of an irrigation scheme had to undergo some studies until it was launched in 2020. As of 2024, the project is still in construction phase where 133km long irrigation canal is being constructed to carry water from Shire river at Kapichira and pass through villages where there will be irrigation schemes until Bangula back into the Shire river. The irrigation scheme when completed is expected to help in the implementation of megafarms strategy where farmers can grow crops all over the year using water from the Shire river to produce much food for the country which boosts food security and gross-domestic product (GDP).

Construction of the irrigation canal

Overall, the benefits of Liwonde barrage outweigh the disparities. Apart from controlled flooding in the lower Shire valley and assisting in irrigation, the Liwonde barrage also provide a room for electricity generation company (EGENCO) to plant hydro-electric power plant to manufacture electricity. It is advisable for people in Mangochi and upper Shire areas to build buildings at a height grater than 477 metres to reduce the disparities. Those residing in the downstream of Shire river must also build their houses far from Shire river banks.