ABSTRACT
Figure 2.1 Location of Matabeleland South Province, the Insiza District and Ward 1
Figure 2.2 The Mzingwane catchment
2.3 The agro-ecological setting Zimbabwe’s rainfall is strongly related to the seasonal movements of the Inter-Tropical Convergence Zone (ITCZ). The country receives summer rains, occurring from the end of October to early March. This is when the ITCZ is above Zimbabwe (De Groen, 2002). Winter, which occurs between May and August, is dry. The northern parts of the country tend to receive more rains than the southern parts, although local relief plays a role in influencing rainfall type and pattern. This rainfall gradient explains why the Mzingwane catchment, which is located in the southern part of the country, is one of the driest catchments in the country. The north-south rainfall gradient is also consistent within the Mzingwane catchment itself with the northern-most subcatchment, the Upper Mzingwane, being wetter than the southern-most subcatchment, the Lower Mzingwane. To illustrate this, annual rainfall at Esigodini (Upper Mzingwane) ranges from 200-1200 mm/a over the last 70 years, while at Beitbridge (Lower Mzingwane) it ranges from 50500 mm/a (Moyce et al., 2006). In the Zhulube catchment, which is in the Upper Mzingwane subcatchment, mean annual rainfall is about 550mm/a (Love et al., 2010). Although this rainfall pattern to an extent explains some of the challenges relating to agricultural production, the region also suffers from periodic extreme weather events which affect Zimbabwe in particular and the southern Africa region in general. One such event was the 1992 drought, which is described in Box 2.1. Box 2.1 The impact of the drought of 1992 In 1992 Zimbabwe experienced its worst drought in living memory (Maphosa, 1994). The drought was not restricted to Zimbabwe but it also affected a number of countries in southern Africa. Within the region received rainfall was below normal by as much as 80%, and this had a huge impact on agricultural productivity (Zinyowera and Unganai, 1993). Zimbabwe was transformed from a food surplus position to being a net food importer (Maphosa, 1994). The Grain Marketing Board (GMB), which is a grain buying parastatal, received only 13 000 tonnes of maize during the year, which was just about enough to feed the country for two days (Maphosa, 2004). More than a million cattle, about a quarter of the national herd, died (Eldridge, 2002). The most devastating impact of the drought was at the household level. Most households only harvested food enough for just about 2-3 months. Apart from impacting on household food security, the drought also affected the Gross Domestic Product (GDP), this being a result of the strong relationship between agriculture and the economy. Most of the rivers in the Mzingwane catchment are ephemeral, flowing only for a few months or even less during the rainy season. This severely limits the importance of rivers and streams as sources of water for both domestic and productive uses. However, dams have been constructed across the major rivers in the catchment such as the Umzingwane, Mwenezi and the Insiza Rivers. These dams are mainly used for irrigation and to supply urban settlements with water. Through inter-basin transfers, for example, the city of Bulawayo which is in the neighbouring Gwayi catchment gets water from the Mzingwane catchment. However, a sad reality in the catchment is that a sizeable proportion of smallholder farmers are unable to utilise water stored in dams simply because there is no infrastructure to convey water from the dams to the farmers’ fields. Box 2.2 describes a condition referred to as a wet drought, which is common in smallholder farming areas in the Mzingwane catchment. Although surface water is scarce in the catchment,
groundwater is an important resource in the catchment. Throughout the catchment boreholes are an important source of water for domestic uses and at the peak of the dry season can be the only source of water available to households. In some parts of the catchment, such as the Lower Mzingwane subcatchment, households make use of water trapped in riverbeds for both domestic and productive uses. Box 2.2 Wet drought in the Mwenezi subcatchment area One of the most critical factors limiting human socio-economic development in the Mzingwane catchment is the shortage of water. As has been mentioned earlier, this is due to prevailing climate in the catchment. However, human factors have also contributed towards limited socioeconomic development in the catchment. The situation in the Mzingwane is an example of what is commonly referred to as a ‘wet drought.’ A wet drought can be considered as being caused by a combination of socio-economically and natural factors. It occurs when, because of insufficiently developed water infrastructure, water users are unable to make use of available water resources and therefore are unable to deal with natural conditions such as low rainfall (see, for example, Mehta, 2001). In the Mzingwane catchment this is illustrated very well in the Mwenezana subcatchment. Within the subcatchment is a large dam, the Manyuchi Dam, which is across the Mwenezi River. The agreement between the state and the private company which developed the dam is that 13.33% of the dam’s water yield should be allocated to surrounding communities. However, to date there has been very little infrastructural development to enable communities within the vicinity of the dam to make use of the water set aside for them. Some of the communities which could make use of the Manyuchi Dam include Maranda, Neshuro, Matibi 1 and 2, Furidzi, Mberengwa, Makuwerere, Mataga, and Gwatemba. This absence of infrastructure to enable the communities to tap the water of the dam results in the communities bearing the brunt of low rainfall totals which could be mitigated by utilising water from the dam. Source: Love et al. 2009. In Ward 1 soil types vary from clays and loams in the north to sandy soils in the south with stony high ground (Tunhuma et al., 2007). Generally the soils are infertile and shallow, which contributes towards low crop productivity in the catchment. Farmers try to improve soil fertility by applying livestock manure. Use of crop residues as manure is done on a very small scale because low crop yields mean little crop residue is available. Furthermore, smallholder farmers prefer to use crop residues as livestock feed. Use of synthetic fertilizers is also very low because factors related to availability, pricing, and access to the market. One can argue that the challenges of crop productivity in the catchment are self-reinforcing and the smallholder farmers are caught in a poverty-trap. The most common type of vegetation in the semi-arid areas of southern Zimbabwe is sweet veld, with comparatively high nutritional value of browse and annual grass species. However, significant proportions of the rangelands are degraded, resulting in low biomass and thus limited feed resources of poor quality particularly during the dry season. Having looked at the agro-ecological setting, which has a strong bearing on the availability of water as a physical resource, the following section analyses Zimbabwe’s political-economic environment, which has an important bearing on water resources management.
