Friday, April 12, 2024

Botswana grapples with drying up limited water resources

In 1991, the United Nations Environment programme (UNEP) reckoned that water is a scarce resource in Botswana that undoubtedly needs good planning which should take into consideration both the short-term and long-term effects of its use.

The United Nations agency also acknowledged that Botswana, Namibia, South Africa and Zimbabwe are the four countries that in Southern Africa already experiencing so-called “water stress”, in other words, the countries have fresh water resources between 1 000 and 1 700 cubic meters per person.

One of the factors related to the scarcity of water in Botswana is the rapidly increasing population associated with a sharp increase in the demand for water. This may lead to water resource depletion if the rate of replenishment is lower than the rate of use.

According to a research publication titled; “Water Resources in Botswana with Particular Reference to the Savanna Regions”, apart from perennial rivers and wetlands in the north and the over-utilized Limpopo and its tributaries in the east, Botswana suffers from a lack of surface water and therefore development relies heavily on groundwater.

“Ground water resources can be found everywhere in the region and is the main source for most of Botswana’s towns and smaller settlements, the livestock industry, its power stations and many mining developments. Rural and remote towns are often entirely dependent upon groundwater except in such cases such as Kasane on the lower Chobe/Zambezi River and Mohembo and Shakawe on the Okavango River,” states the research paper.

The study is quick to point out that other factors influencing water availability and distribution in Botswana are the low and variable rainfall, high rates of evaporation and high costs of the exploitation of the existing surface water resources.

The paper notes that water supply management requires the development of affordable self-financing facilities for bulk water supplies, programmed to meet expected increases in requirements with an appropriate degree of assurance.

With this in mind, it is essential that water supplies should be managed in terms of the relation between the amount of water required in various sectors of an economy, and the contribution of the respective sectors to the Gross Domestic Product (GDP). Management-related problems of supply systems usually include factors such as lack of reliable information, policies and programmes to maintain and expand existing systems.

The semi-arid climatic conditions of the Southern African region have also been found to underpin the management strategies for both the groundwater and surface water resources. Over 90 percent of the rainfall in Botswana occurs during the summer from November to March, mainly in the form of scattered connective thunderstorms. Hailstorms are common at the beginning and end of the rainy season.

The variability of the rainfall, in terms of the amount and timing, as well as the length of the wet season, lead to higher risks in, for example, the cultivation of crops. The temporal distribution of rainfall in Botswana is extremely variable but tends to be more reliable in the higher rainfall areas in the north of the country.

According to the research paper, drought is a phenomenon that seriously influences the availability of water in the environment. Botswana is a country that is particularly drought prone compared to the rest of the Southern African countries in terms of the frequency and duration of drought events.

The study further reports that water resources in Botswana are generated within the basins of four major rivers: the Limpopo; Okavango; Orange and Zambezi Rivers. Apart from the Okavango river, all shared river systems flow away from Botswana and only a small area of these basins lie within the country.

As for surface water, the resources are mostly located in the sparsely populated districts of Ngamiland and north-western Botswana where the perennial Chobe, Okavango and Zambezi rivers are found. In the eastern part of the country, where more than 80 percent of the population lives, all the rivers are ephemeral. Concentration of the population in towns and urban villages results in an increase in the local demand for water and, therefore, development in these areas relies heavily on groundwater.

The report says the development of surface water in Botswana is constrained by a number of factors such as its low and erratic run-off, lack of available sites, and high rates of evaporation. Approximately 35 percent of the total water supply is from surface water, whereas the remainder (65 percent) is from groundwater.

According to the report, it is evident that Botswana suffers from a lack of internal renewable resources and therefore relies heavily on surface water generated outside the country. Water transfers (as part of the potential renewable sources available to Botswana) are likely to make an increasing contribution to the country’s water supply.

Botswana’s water resources must therefore be assessed in the context of the total resources available in the shared river basins. On particular attention to groundwater that contributes 65 percent of the total water available in Botswana, the quantity of groundwater resources has been found to be limited. Evidence suggests that groundwater is used at a rate higher than the rate of replenishment in many parts of the country.

Recharge of aquifers ranges from over 40mm/year in the extreme north to virtually zero in the central and western parts of the country. The average recharge is only 3mm/year.

The study also found that groundwater resources have potential to sustain more extensive human habitation in the Kgalagadi as the demand is geographically spread according to the study which further advises that “careful monitoring as well as hydro-geological knowledge is needed to secure the sustainability of this valuable resource”.

On the downside, it is reported that pollution of underground water poses serious threat to users, especially those in rural areas where groundwater is the main source for domestic use and livestock watering. A possible cause of nitrate pollution in Botswana could be the organic waste from pit latrines and septic tanks, mostly in rural areas.

The study also observes that the total demand for water may further be increased if the outputs of agriculture, industry and commerce are expanded in line with the development strategy of the government.

“It is evident, therefore, that a carefully worked out water management strategy in Botswana is urgently needed as environmental demands for water are bound to come into direct competition with the agriculture, household, and industrial projects”, states the study.

Yet another study titled: Water Demand Management in Botswana: Reflections on the latest review of Botswana National Water Master Plan” concurs that Botswana is a water scarce country with limited water resources and yet it is estimated that as much as half of it is wasted through leakage, lack of effective water demand management programmes and inefficient management practices.

The research study also acknowledges that with the population becoming more affluent, water demand is escalating. The limited water resources are drying up with the problem compounded by the large distances between the major demand centres and the sites of potential water sources which translates into large portions of money being devoted to development and bringing the water resources closer to the demand centres.

With this precarious situation, water demand management is seen as critical in securing the future as opposed to supply management, where the primary strategy to meet the demand is by increasing the supply. The primary objective of demand management is to rationalize and control water use, reduce waste and increase use efficiency and equity in view of the limited supplies.

“Water is scarce in the country, so to manage a scarce commodity amidst the growing water demand resulting mainly from increased population is a formidable task in itself”, states the study which acknowledges that the population of Botswana “is increasingly becoming more affluent and urbanization in Botswana is ranked among the fastest in Africa”.

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