The Gwayi catchment consists of five sub-catchments, with total area of 87 960km2. Gwayi catchment largely comprises the Northern Matabeleland area of hydrological zone A, excluding sub-zones AZ3 and AZ4 that are now part of the Sanyati Catchment
There are twelve Rural District Councils (RDC’s) which fall either wholly or partially within the Gwayi catchment. The catchment water management structures are to work closely with district water development planning processes to ensure that they are coordinated in various sub-catchments.
The altitude of the Gwayi catchment varies from the lowest 600m to as high as 1500m. The high altitude zone forms the source of most rivers as the catchments. Nkayi, Bubi and Mguza areas range from 900—1500m above sea level, Hwange ranges from 940 to 1000m, Lupane area ranges from 950m—1120m and Binga ranges from 600m—1200 m above sea level.
The mean annual temperatures for the Gwayi catchment vary from 8.5 to 32 Degrees Celsius. The temperatures rise in September to reach a peak of about 38 Degrees Celsius during the summer months of October, November and December and then steadily decline to lowest temperatures of around 2.5 oC during the winter months of June and July before they begin to rise again.
In Tsholotsho, temperature ranges between 8.6oC and 38oC with a mean of 19 oC. The annual mean minimum temperature in Bubi is about 13 oC and the mean maximum temperature is around 26 oC. In Lupane area, mean daily temperatures rise in September to reach a peak of 25 oC during the summer months and steadily decline to a minimum of 15 oC during the winter months of June and July. Mguza has a mean minimum temperature of about 13 oC and the mean maximum temperature of 26 oC. The lowest temperatures occur in June/July and are usually below 10 oC while the maximum occurs during summer and are occasionally above 28 oC.
Temperatures of up to 45 oC are recorded in low-lying areas of Hwange. The average winter maximum temperature for Hwange town is 2.7 oC (June/July) and the average summer maximum temperatures ranges from 39.4 oC to 43.3 oC (October—December). The annual mean minimum temperature for Nkayi area is 13 oC and the annual mean maximum temperature is around 26 oC. The minimum temperature is recorded in June/July and is usually below 10 oC.
All the runoff is derived from rainfall, and therefore temporal and spatial variations of rainfall greatly influence runoff patterns within Zimbabwe. Rainfall that is transferred into runoff is received during the November to march period while the rest of the year is dry. Within the Gwayi catchment the highest rainfall occurs during the December to February months that have mean monthly rainfall from 120mm 180mm/month. Consequently peak flows are experienced during this period within the Gwayi catchment.
The highest rainfall is experienced on the headwaters of Shangani River (620-640mm/year), and also in sub-zones AZ2 (Binga and Kariangwe area) and AR, (Siabuwa) area with 620-706mm/year. Sub-zone AK, which covers mostly parts of Hwange National park has the lowest rainfall, 550mm/year. Table below presents mean annual rainfall for selected stations within the Gwayi catchment.
The catchment is covered by Natural Region 1V and V with region 111 covering only very a small area, hence the catchment receives below average annual rainfall. The rainfall has however, become unreliable and unpredictable as evidenced by persistently recurrent droughts over the last 20 years. The rainfall period commences and ends in October/November and March/April respectively. The dry season with low or no rainfall covers the rest of the months. The highest rainfall figures are recorded in the months of December to February and the lowest in August and are usually less than 1mm on average.
The mean annual rainfall for the catchment is 650mm for Hwange area, 700mm for Tsholotsho, 674mm for Nkayi 560mm for Mguza area, 620mm for Lupane, 600mm for Bubi, and about 650mm around Binga area.
The main socio-economic activities in the catchment are game ranching, fisheries and boating. Prominent Safaris in the catchment where game viewing and hunting activities takes place is Hwange National parks and other private Safaris like Ngamo Safaris Touch the Wild, Matetsi Ranch etc.
Most fishing and boating activities take place along the Zambezi river. The likes of these activities and Vic Falls have attracted significant number of foreign visitors in the catchment.