Nyamandlovu Aquifer

The Nyamandlovu Aquifer is located in the Forest Sandstone. The thin layers of Kalahari sand in the area are not sufficient to contain large amount of water. Bulawayo, the second largest city in Zimbabwe with a population of about one million people and has been facing water problems since the beginning of the 1990s. A well field was drilled in the Nyamandlovu aquifer in 1996 for immediate water supply for the city due to continued water crisis. However, the aquifer is also heavily exploited by the local farmers in the Nyamandhlovu area. Due to over -exploitation of the aquifer, research has been initiated both for management of the aquifer and to identify alternative aquifers.[1]

Background

The Forest Sandstone is widely developed in the Hwange – Zambezi Basin and constitutes an important regional aquifer, with high groundwater development potential. It is mainly confined, being unconfined only close to outcrop. Boreholes are typically 30 – 100 m deep, with water levels sometimes less than 10 m depth but more commonly greater than 20 m depth. Yields range from 0.1 to 5.9 l/s. Recharge estimates indicate an annual recharge of 105.5 mm with 38.4%, 52.1% and 9.5% accounting respectively for direct recharge, water mains and sewer leakages.

Geology

The Nyamandlovu area lies about 40km NW of Bulawayo on the edge of the Kalahari sedimentary basin. Thin patches of Kalahari aeolian sands cover Karoo basalts in some places. The basalts overlay the Forest Sandstone which rests directly on the granitic gneiss basement complex. The geology information from boreholes suggests that the sedimentary sequences dip NW and thicken towards Sawmills. The basalts have been heavily weathered and fractured in places with thickness varying between 15m to 30m. Only the Upper Karoo formation is identified in Nyamandlovu with a thickness of up to 200m.

Water Challenges in Bulawayo

Bulawayo residents endured more than four days a week without water supplies for most of 2020 after council announced that it had considered reviewing upwards the water shedding schedule. The local authority had some projects they targeted to do that included further development and extension of the Nyamandlovu Aquifer towards Sawmills in Tsholotsho, after which it was envisaged to supply an estimated combined ground water potential yield of 20 megalitres a day. In March 2020, the Nyamandlovu Aquifer scheme supplied on average three to four megalitres a day.[2]

Rehabilitation

In May 2020 the rehabilitation of 15 boreholes at the Nyamandlovu aquifer was started with the Bulawayo City Council (BCC) pinning on the project to ease the water woes in the city. The Government availed ZWL$10,6 million in April 2020 to Zimbabwe National Water Authority (ZINWA) to enable the authority to rehabilitate the boreholes to improve the water situation in the city.[3]

Commissioning of the Aquifer

President Emmerson Mnangagwa commissioned the Nyamandlovu Aquifer water project, a development that is expected to enhance water supply in the second largest city of Bulawayo by providing 20 million liters of water daily.



References

  1. Patience Gwaze, Torleif Dahlin, Richard Owen and Oswald Gwavava, [1], Research Gate, Published: September 2000, Accessed: 26 February, 2021
  2. Vusumuzi Dube, [2], The Sunday News, Published: 29 March, 2020, Accessed: 26 February, 2021
  3. Senzeni Ncube, [3], Centre For Innovation and Technology, Published: 9 May, 2020, Accessed: 26 February, 2021