Resulting from altering local weather & rising inhabitants, lots of Africa’s floor water sources like dams & rivers are overused & slowly depleted
Discoveries of aquifers — underground earth formations that maintain water — typically create pleasure round their capability to ease water shortage in a area.
For example, about 10 years in the past a big aquifer was discovered in Kenya’s Turkana area. This is likely one of the hottest, driest elements of Kenya and it continuously suffers from drought. The federal government claimed that the aquifer might provide the whole nation with water for 70 years. Extra just lately, the US introduced the discovery of 5 aquifers in Niger, considered one of Africa’s most water scarce international locations, containing over 600 billion cubic metres of water. To place it into perspective, Egypt’s present water demand is 114 billion cubic metres of water per yr.
These are welcome bulletins. Resulting from a altering local weather and the rising calls for of a rising inhabitants, many of Africa’s surface water resources — comparable to dams and rivers — are below pressure. They’re being overused and slowly depleted.
Different water sources, like aquifers, have to be explored. Based mostly on Africa’s geology we all know aquifers are highly prevalent throughout the continent. However, as a groundwater and aquifer skilled, I need to spotlight that they’re not at all times going to assist handle water shortage. For example, early analysis findings deemed Kenya’s Turkana aquifer water unfit to be used as a result of excessive salinity.
It’s necessary to bear these challenges in thoughts in order that expectations could be managed. Additionally it is helpful for planners and governments, as they want to think about different methods across the water shortage downside.
The amount of groundwater that’s held in African aquifers is estimated to be 0.66 million km³. That is greater than 100 occasions the annual renewable freshwater sources saved in dams and rivers, and 20 occasions the freshwater saved in Africa’s lakes.
The scale and form of an aquifer is based on the physique of rock beneath the Earth’s floor. Some could be within the type of caves and maintain water on a big scale. Some can vary from a couple of metres thick to tons of of metres with a number of layers. Aquifers also can prolong for a lot of kilometres or be localised in sure areas.
Water will get into these aquifers in several methods. Some are crammed by new rainfall, others maintain previous, or historic, rainfall. In Africa, most are discovered lower than 50 metres under the bottom’s floor.
Lots of Africa’s aquifers are spread across country borders, that means international locations must share the water useful resource. The most important volumes of groundwater in Africa are found in giant aquifers in Libya, Algeria, Egypt and Sudan.
There are numerous methods to faucet into aquifers, together with hand-dug wells, drilled wells and boreholes, and natural springs.
Tapping into the groundwater
Some international locations have already taken steps to faucet into aquifers.
South Africa has two huge aquifers. The most important stretches from Cape City to Gqeberha, a metropolis 750km away. This geological formation covers a floor space of 37,000km² and ranges in thickness from 900 metres to 4,000 metres. The opposite large one is the Cape Flats aquifer. It’s estimated that by 2036, nearly R5 billion (about US$274 million) may have been invested to faucet these aquifers. They may yield about half of the quantity of water within the Berg River dam, which supplies almost 20 per cent of the Metropolis of Cape City’s provide.
One other giant aquifer on the continent, containing solely historic trapped water, is the Nubian Sandstone in North Africa. It covers about 2 million km², and spans Libya, Egypt, Sudan and Chad. It incorporates greater than 150,000km³ of groundwater — extra water than the Nile River discharges in 500 years. The international locations it spans are tapping into the aquifer and have agreed on its honest use.
Libya has undertaken the Great Man-Made River project to pipe water tons of of kilometres from the Nubian sandstone to the coast by way of gravity movement.
Challenges in utilizing aquifers
However aquifers aren’t a silver bullet. There are various components to think about when utilizing them as a water supply.
The gap between the aquifer and the place the water is required could be an impediment. In some locations in Africa, this distance is roofed by girls carrying buckets and strolling for a lot of kilometres. The development of pipelines and infrastructure could be pricey.
A associated problem is the depth required to drill for groundwater, which might incur nice prices. A kind of X-ray is finished of the floor to substantiate whether or not there are groundwater sources value exploiting, after which there’s the expense of a drilling rig.
Water high quality
Water high quality in an aquifer isn’t at all times good. Generally it’s polluted by human exercise; generally the water takes on traits of the encompassing materials within the floor.
An instance is exterior Gqeberha, which has one of many largest drilled wells within the Southern Hemisphere. It yields about 100 litres per second. Sadly the iron content material of the water is above the required standards. It needs to be handled earlier than it’s drinkable.
Unsustainable groundwater use
Overpumping is turning into frequent in sure areas, particularly cities. Cape Town and Nairobi are reporting tons of of nicely factors being drilled for residents to make use of. Instances of wells drying up and water ranges dropping quickly have been reported in locations.
Industrial exercise, agriculture and chemical leaks also can have an effect on groundwater high quality.
Overpumping also can trigger seawater to get into groundwater. The extra dense seawater migrates to switch the freshwater faraway from an aquifer. This has devastating implications for the storage capability of the aquifers in addition to the general groundwater high quality. It has been seen in certain coastal aquifers. Saline intrusions are very tough to handle.
Assembly water wants
Regardless of these issues, aquifers have the capability to offer some water in nearly all elements of Africa. Groundwater is a part of the answer to water shortage, however not the whole answer. It must be utilized in a manner that retains it out there lengthy into the long run.
Gaathier Mahed, Senior lecturer, Nelson Mandela University
This text is republished from The Conversation below a Artistic Commons license. Learn the original article.
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