Runde catchment lies in the south-eastern semi arid to arid region of Zimbabwe (Figure 2.1). Its catchment area is 41 056km2. The main river systems in the catchment are Chiredzi, Mutirikwi, Shashe, Tokwe, Runde, and Ngezi Rivers. The catchment is divided into 5 sub-catchments according to the main river systems namely Upper Runde, Lower Runde, Tokwe, Mutirikwi and Chiredzi. There are 21 hydrological sub-zones with areas varying from about 607 to 5802 km2.
The mean annual rainfall for sub-zones varies from 530 mm/year to 819 mm/year, while station rainfall varies from 439 mm/year at Makonese Irrigation to 1024 mm/year at Morgenster Mission. About 90% of the precipitation occurs during the period of mid-November to early April (Met Dept). The winter season is from April to August, and the hottest and driest period is from September to mid-November.
Chivake dam was built with a full supply capacity of 5,320 ML and a 10% yield of 1,800ML/annum while Banga dam was built with a full supply capacity of 1,300ML and a 10% yield of 600ML/annum. The two dams though 5km apart, they augment each other by pumping water from Chivake to Banga dam. Both dams augment the Ngundu water supply and the existing Banga irrigation scheme. About 55.6 hectares were earmarked for irrigation purposes while Banga dam was overloaded by about 25.5hectares so Chivake dam will augment this while ensuring that Ngundu water supply gets water throughout the year.
This dam is located in subzone EL2 on the Chedozvo stream in Mwenezi district under Lower Runde sub-catchment. It’s estimated full supply capacity is 2,865ML and a 10% yield of 400Ml/annum. It supplies water to Sarahuru Rural service centre hence it cannot be allocated to any irrigation scheme because of the 21-month rule that applies to all water supply sources. The only alternative is to optimize water usage from this source is to increase the clear water consumer base.
This dam was built with a full supply capacity of 2,488ML and a 10% yield of 427ML. This dam located in EL2 was meant to supply water to Lundi Rural service center, Lundi mission, Rhino Park Motel and the surrounding villages and schools. This dam is still underutilized however due to the 21-month cushion meant for water supply dams it was deemed safe to retain the water for future water supply expansions, environmental, domestic and livestock purposes.
Tokwe Mukosi, Muzhwi, Bindamombe, Tokwane dams. Of these only 2 dams are underutilized. These are Bindamombe and Muzhwi dams. There are quite a number of small dams that can be used for irrigation though at a smaller scale.
This dam was built with a full supply capacity of 22,583ML and a 10% yield of 6,044ML. This dam located in ET2 under Chivi district. This area the area is prone to drought hence a potential of irrigable land of 400 hectares were earmarked for irrigation to benefit the local community downstream. At the time of writing this outline plan works on the scheme had begun. Hopefully the scheme will become a reality since the dam has been lying idle for 10years due to lack of funding.
This dam was built with a full supply capacity of 106,961ML and a 10% yield of 60,000ML. This dam located on the northern part of Mashava area of Chivi District This dam was built to augment the Tokwane dam, which could not supply the lowveld with enough water. About 55,000ML was allocated to the lowveld consumers while the remainder can be used for irrigation. However it should be noted that according to present consumption lots of water remains underutilized. About 4,433hectares can be irrigated by the water from Muzhwi dam. Once the Tokwe-Mukorsi dam is complete this dam should benefit those closer to it as compared to distant water users downstream.
Most of the dams in this catchment are over utilised. The combined yield for Lake Mutirikwi, Bangala and Nyajena is about 519,000ML yet the recorded commitment is 437,000ML. Though it might look like the dam is under utilized it should be noted that not all water users are registered. There are quite a number of small dams that can be used for irrigation though at a smaller scale.
This dam is located in subzone EUT3/4/5 on the confluence of Mutirikwi, Popoteke, Bevume and Mushagashe Rivers in Masvingo district in Mutirikwi sub-catchment. It has a proposed capacity of 1,378,082Ml and a 10% yield of 383,958Ml/annum. About 362,000ML is committed.
This dam was built with a full supply capacity of 126,588ML and a 10% yield of 130,000ML. This dam located in Masvingo district under chief Nyajena. This dam is the main one for the Mutirikwi system as can be seen on the yield, which is more than the full supply capacity. Its water is fully committed to the lowveld irrigation. The bulk of this allocation belongs to Hippo Valley estates while the remainder belongs to Triangle estates.
This dam was built with a full supply capacity of 6,148ML and a 10% yield of 4,900ML/annum. This dam acts as a weir or the gateway for the Mutirikwi system. Its main advantage is that it uses gravity to divert water that sustains thousands of hectares under sugarcane. It has since silted up to an extent that it’s now an abstraction or diversion weir. The lowveld estates rely on this weir more than it does on river flow.
This sub-catchment is the smallest in Runde catchment. However its storage far exceeds its MAR. It relies on water from Save catchment under the inter basin transfer. Extensive irrigation schemes in the Mkwasine area consume 90% of its water. There are several small dams that are under irrigation while some supply water to rural service centers. There are only two dams considered to be major in this sub-catchment. There are quite a number of small dams that can be used for irrigation though at a smaller scale.
This dam was built with a full supply capacity of 274,179ML and a 10% yield of 105,000ML. This dam located in Zaka district under EC2. Its commitment is as high as 165,000ML. It gets augmentation from Siya dam that supplies 60,000ML/annum to meet the demand. No further developments are expected from this source.
This dam was built with a full supply capacity of 2,597ML and a 10% yield of 1,929ML. This dam located in Zaka district under EC2. Nyatare dam irrigates about 25 hectares at the moment while some water is used to supply water to Zaka and Jerera. This dam may seem to be underutilized however due to the 21-month rule that cushions water supply dams. It was deemed safe to retain such water for future water supply expansions, environmental, domestic and livestock purposes.
UPPER RUNDE SUB-CATCHMENT
This sub-catchment has 4 major dams and many small ones. This sub-catchment encompasses Masvingo, Midlands and Matebeleland South province. Most of the detail concerning water and irrigation schemes is not up to date. There are quite a number of small dams that can be used for irrigation though at a smaller scale.
This dam was built with a full supply capacity of 72,320ML and a 10% yield of 33,290ML. This dam is located in Zvishavane district under EN2 along the Ngezi River. Its commitment is 5,160ML catering for Zvishavane Town and Mimosa Mine. This dam is underutilized to an extent that 1,600 hectares of land can be opened for irrigation.
Gwenhoro and Amapongokwe dams
The 2 dams were constructed for supplying water to Gweru city council. The dams have a combined yield of about 32,000ML while the current abstraction per year is about 18,000MLThe present remaining water after Gweru has abstracted its water is about 14,000ML. Though it seems that these dams are still underutilized, the 21-month rule cushion meant for water supply dams. It is safe to retain the water for future water supply expansions, environmental, domestic and livestock purposes.
The mean annual runoff (MAR) shows a greater variation than rainfall ranging from 4mm recorded during the 1992 drought period to around 900 mm recorded in 1973. Spatially the MAR varies between 23 mm in the southwest of the lowveld to about 113 mm in the Shurugwi area.