IN sub-Saharan Africa, water is present but scarce, without the capital to access it.
Besides affordability and ensuring the human right of access to water, ensuring environmental flows, ecosystems services and non-consumptive use of freshwater resources, good water governance is critical and calls for adaptive management at the catchment level to address the needs of all water users.
For service providers to improve and expand access to water, they need the skills to design, operate, maintain and repair essential technologies to optimise the efficiency of water use and systems, such as irrigation, expected to more than double in sub-Saharan Africa by 2050, as their misuse will result in water and yield losses.
Currently, more than 80 percent of cropland in sub-Saharan Africa is low-input rain-fed production, with only three percent irrigated.
In Zimbabwe, irrigation accounted for 80 percent of the developed surface water while the urban, industrial and mining sub-sectors accounted for the remaining 20 percent.
Expanding small-scale irrigation can be profitable and can benefit between 113-369 million rural small-scale farmers across the continent.
For the estimated 171 million hectares (or 62 percent) of the world’s irrigated cropland under high or very high water stress, priority should be given to incentivising practices that increase water productivity.
However, this requires complex collaboration across several stakeholders, locations and entities. Improved co-ordination is needed from sectoral, river-basin and water systems, to consumers and across all sectors, including agriculture, industries, municipalities and households.
And 4,7 cubic km or 55 percent out of a total estimated annual potential surface water yield of 8,5 cubic km has been developed, with only a minor part of the potential groundwater resource utilised.
Threats to water resources include reduced ground cover and expansion of human settlements that increase surface water run-off, leading to soil erosion and siltation of water bodies.
They also decrease the rate of infiltration, which slows the recharging of underground stores. Population growth, demand for water from growing economic activity and increased consumption are widening the gap between water supply and demand.
Pollution of surface and underground water and inappropriate irrigation methods can lead to a damaging build-up of salt in soil (saline soil), reduce the amount of freshwater that can be used and degrade soil quality for agriculture production, which, in turn, can increase pests and diseases.
The total available water in Zimbabwe is presently estimated at around 20 million megalitres (1 mega litre equals 1 million litres or 50 000 x 20-litre chigubus).
This is in the form of surface water such as streams, rivers, dams, underground stores, including wetlands and aquifers as well as water-storing rock.
It is estimated that eight million megalitres of underground water is available through wells and boreholes.
This supports 70 percent of Zimbabwe’s population, mainly in rural areas. Most water demand is agriculture-related, for irrigation and livestock. Shallow wells, which serve most families in rural areas, draw on water stored in the soil.
These tend to dry out with use and when the water table (the level of water in the soil) lowers as the dry season progresses.
However, wells quickly recover their capacity if rainwater is able to flow through the soil to recharge the water table and if the soil in the area is protected (by trees and other vegetation) to reduce compaction and erosion.
Boreholes, on the other hand, tap into aquifers and are a more reliable water source.
Depending on the rock type, some underground aquifers are recharged by rainfall; non-rechargeable aquifers become permanently dry once the water has been extracted.
The recharge and occurrence of groundwater is also highly variable, depending on varying local
catchment conditions.
The recharge estimate of 3,7 cubic km corresponds to an average recharge of 1,5 percent of the rainfall.
Groundwater levels also vary substantially with rainfall.
There has been a steady decline of the levels during periods of low rainfall.
There are indications of groundwater tables in certain parts of the country having been even lower during a period of low rainfall about 25 years ago that recovered.
This, however, may not be possible with the current climate change.
Surface water was developed through a system of more than 8 000 dams — the largest of which is the Kariba Dam on the Zambezi River — with a capacity of 160 368 million megalitres, followed by Tokwe-Mukosi Dam with a capacity of 111 750 million megalitres and Lake Mutirikwi with1 425 million megalitres.
Kariba supplies 80 percent of Zimbabwe’s electricity, and although electricity generation as such does not consume water, it relies on adequate flows and storage.
Climate change will affect the generation of electricity from hydropower since lower rainfall means less water in Lake Kariba, resulting in less generating capacity.
The net evaporation losses from this reservoir are in the region of seven cubic km per year.
Research shows that surface water resources within Zimbabwe will reduce significantly by 2080.
This will place a great number of the population at risk of water shortages. The western and southern parts of Zimbabwe are projected to experience drying up, leaving millions of Zimbabweans at risk of hunger and poverty.
Water stress is also likely to adversely impact public health, water availability, forestry and biodiversity, rangelands, human settlements and tourism.
Already, over the past century, the annual rainfall in Zimbabwe has declined by five percent across the country.
The country also experiences droughts lasting one to three years which occur every five-seven years.
However, drought and water scarcity would be more efficiently counteracted through a long-term programme of optimal resource development and improved water management than through crisis management and crash drought-fighting programmes.
Over a billion people in developing countries lack safe drinking water. Nearly three billion people live without access to adequate sanitation systems necessary for reducing exposure to water-related diseases, hence causing unnecessary and preventable suffering.
An estimated 14-30 thousand people, mostly young children and the elderly, die everyday from water related diseases, while approximately half of the people in the developing world suffer from diseases caused by drinking contaminated water.
Adequate water supply and sanitary facilities are of the utmost importance in reducing diarrhoea and other infectious diseases.
Dr Michelina Andreucci is a Zimbabwean-Italian researcher, industrial design consultant and is a published author in her field. For comments e -mail:linamanucci@gmail.com
