This chapter sought to assess sector-based current water use levels in Sanyati catchment, assess a possibility of new ways of managing the catchment water using inter-basin transfer systems, and assess future water demands projection using WEAP model. The study was both quantitative and qualitative in nature. Interviews and observations were the main primary data collection instruments. Findings showed that the main sectors and institutions that utilised water in the catchment were mining, agriculture, manufacturing industry, and local authorities. Local authorities and farming sectors were the major users of water. WEAP model results showed a steady increase in demand for water as a result of both population growth and agricultural activities water demand. The study mapped possible inter-basin transfer routes and recommends water harvesting as part of development and management in Sanyati catchment to address the problem of water shortage.
TopIntroduction
Global consumption of water is doubling every 20 years, more than twice the rate of human population growth (United Nations 2011). If the current trend persists, by 2025 the demand for fresh water is expected to rise by 56 percent more than is currently available. Water as a natural resource is scarce and requires integrated approaches in its management. The supply of water is limited but the demand for water is increasing rapidly on a global scale. The imbalance between water supply and demand is expected to greatly expand as water demand inevitably increases. With respect to total water demand, agricultural demand is the largest globally whereas demand in the municipal and industrial sectors is increasing significantly (Shiklomanov, 2000). Almost 70% of the extracted fresh water is utilized for crop-raising activities globally (FAO, 2013), and more water is required in order to produce more food in the future. It is believed that if water is utilized effectively in agriculture, it will not be a bottleneck for future food production (De Fraiture and Wichelns, 2010). The demand for municipal and industrial uses is expected to increase rapidly in the near future due to burgeoning urbanization and industrialization. More specifically, the increases between 2000 and 2050 will mainly come from manufacturing (400%), electricity (144%), and domestic uses (127%) (Leflaive et al., 2012),
Water scarcity has been a critical issue for many regions and has caused numerous water conflicts. In Southern Africa, water is key to winning the battle against poverty and its scarcity could be a limiting factor to growth. Southern Africa’s water sector is already being affected by unsustainable water and land use practices, over pumping, flooding, watershed degradation, wetland loss, and proliferation of aquatic weeds, sedimentation, and climate variability. No socio- economic development can take place without water. Zimbabwe's water resources are indeed limited and scarce. The situation is worsened by the occurrence of droughts and the increasing demand associated with population growth and a developing economy. Zimbabwe is an atypical sub-tropical country with one rainy season (November to March). The country’s average rainfall is 657 mm/annum and varies spatially from the eastern highlands (1,000mm) to low lying areas such as valleys (400 mm) in the southern part of the country. Specifically, agriculture normally requires a sizable amount of water during the crop growing season, and much less water during the other months of the year. The improvement in water use efficiency and productivity is widely considered as the best solution to ensure that future water demand does not exceed water availability, and this requires special attention on the demand side.
Kjeldsen etal (2009) argue that in the last 20 years Zimbabwe has experienced periods of severe droughts, increasing the pressure on available freshwater resources and enhanced the occurrence of conflicts between water users. Unreliability of precipitation for the past decades in Zimbabwe has seen many problems arising in water supply for both rural and urban users (Chigumira and Mujere 2015). The Sanyati catchment runs through four different natural regions (1-4) with varying average rainfall amounts and hence the water demand levels are different and must be managed accordingly. The Sanyati catchment receives its rainfall in the upper reaches of the catchment, rainfall decreasing gradually towards the west. Surface water availability follows the same trend with the upper catchment having almost perennial flow. Rivers such as Munyati and Mupfure in Sanyati Catchment are perennial but in dry years these rivers dry up during August to November (Kjeldsen etal 2009).