Kamuzu Dam 1 Raising and Rehabilitation

The Lilongwe Water Board (LWB) abstracts its water from the Lilongwe River, which feeds into Kamuzu Dam I (KD I) and Kamuzu Dam II (KD II) reservoirs. KD I and KD II are situated on the Lilongwe River in the Central Region of Malawi, approximately 25 km southwest of the capital city of Lilongwe. KD1 is located at latitude 14° 105′ S and longitude 33° 38.5′ E (UTM: 569 250E, 8432 912N Zone: 36L), immediately upstream of the Malingunde bridge. KD2 is approximately 5 km downstream of KD1, with the KD2 reservoir extending back to the toe of KD1. The two dams, with a combined live storage capacity of 23.4 million m3 operate in series to store and release raw water, which is abstracted from the river by LWB at a point downstream for treatment and distribution to Lilongwe City.

The catchment of the Lilongwe River is the Dzalanyama Hills. It is augmented by the Lisungwi and Likuni Rivers only in the rainy season. The two dams upstream of the intake works act as storage for the dry season, during which the flow from the Lilongwe River cannot sustain production. 

Construction of Kamuzu Dam I started in 1963 and was completed in 1966. The catchment area is 767 km2. The dam was raised by 1.2m in 1987 to a storage capacity at Full Supply Level (FSL) of 5.1 million cubic meters.

Construction of Kamuzu Dam II started in 1989 and was completed in 1992 with a raw water storage capacity of 9.2 million m3. The dam was raised by 5 meters in 1998 using concrete fusgates,es thereby increasing the raw water storage capacity from 9.2 to 19.8 million m3.

In order to manage water supply limitations and deficits arising from the growing water demand in Lilongwe City, LWB conceptualized the project for the raising and rehabilitation of Kamuzu Dam 1 to increase the storage capacity of Kamuzu Dam I. This would be achieved by raising the full supply level of Kamuzu Dam I by 7.0m and increasing the storage capacity from 5.1 million m3 to 25 million m3.

Project Scope

The project scope included the following main features:

  • Raising of the Left Embankment by 3.3m from El. 1105.70m to El. 1109.0m and a parapet wall to El. 1110.20 m The length increased from 220m to 290m. The upstream slope is protected with rip-rap against erosion and grassing for downstream slope protection.
  • Raising of the non-overflow section by 4.5m from elevation 1104.5m to 1109.0 m  Vertical post-tensioned anchors installed in the existing concrete.
  • Raising the existing spillway by 5m from El 1100.0m to El 1105.0m and increasing the length from 96m to 165 m
  • Construction of the new Right Embankment. The crest elevation is 1110.2m and the width is 4m. The upstream slope is protected with rip-rap against erosion and grassing for downstream slope protection.
  • Construction of new left and right retaining walls to support and protect the left and right embankments.
  • Construction of a new bottom outlet in the existing intake structure.
  • Installation of a 2.0-meter-high rubber dam on the spillway crest, including the installation of hydro-electrical and mechanical works in the control building

Construction Details

LWB signed a Works Contract for Raising and Rehabilitation of Kamuzu Dam I with Mota-Engil Engenharia e Construcao Africa, SA, on July 27, 2018. The contract commencement date was November 5, 2018, with an original completion date of November 6, 2020. The accepted contract amount was US$16,241,428.17, revised to US$22,708,664.16 due to changes to the design, especially the spillway and bottom outlet works.

The design and construction supervision of the works were done by Studio Ing. G. Pietrangeli S.r.l. (SP). The service contract was signed on May 24, 2018, with an original contract amount of EUR 1,228,025.00 revised to EUR 2,734733.00 to cover the extended period for construction supervision.

Implementation of works was adversely impacted by COVID-19 lockdowns and travel restrictions, which disrupted supply chains for imported materials and equipment as well as the mobilization of skilled personnel for specialized activities such as grouting, electro-mechanical works, and instrumentation. Additionally, the implementation of works was also adversely affected by abnormal floods caused by three cyclones (Anna, Gombe, and Dumako) experienced during the 2021–2022 wet season.

Financing

The project was financed by the European Investment Bank (EIB) under the Lilongwe Water Resource Efficiency Programme. Furthermore, the Lilongwe Water Board and the Government of Malawi contributed MK1,900,000,000.00 towards resettlement costs for project-affected persons and relocation of affected structures.

Expected Benefit

With the raising of Kamuzu Dam 1, the combined storage capacity for both Kamuzu Dam I and Kamuzu Dam II increased from 23.4 million cubic meters to 43.4 million cubic meters. This has enhanced the water resource security for Lilongwe City and surrounding areas in the short to medium term.

Other complimentary Projects

Lilongwe Water Board Treatment Works III

An additional production of 50,000 cubic meters will be realized from the increased water resource. This additional capacity will provide sufficient water to supply an extra 500,000 people in Lilongwe City and surrounding areas, meeting the current demand for the city up to the year 2027. The project will be made possible with €15 million support from EIB and Co-financing of 2.5 million from the World Bank through the Lilongwe Water and Sanitation Project (LWSP)