Going underground for water

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first_imgThe total volume of water in aquifers is more than 100 times the amount found on the surface and 20 times the fresh water stored in African lakes.The World Economic Forum in Africa has already flagged water security as one of the fastest-growing social, political and economic challenges today. (Image: Flickr)Wilma Den HartighMany African countries have always been considered water scarce, but new research findings suggest that the continent isn’t as dry as previously thought. Scientists have for the first time produced the most detailed maps yet which show that Africa has vast reserves of groundwater, hidden in aquifers under the surface.This incredible discovery by researchers from the British Geological Survey (BGS) and University College London is good news for a continent that is considered one of the most vulnerable regions in the world to global warming and climate variability.The new report, Quantitative maps of groundwater resources in Africa, published in the environmental research letters journal on IOP science online, comes at a time when water security in Africa has become a talking point.According to the paper, the maps indicate that the total volume of water in aquifers is more than 100 times the amount found on the surface and 20 times the fresh water stored in African lakes.This is a considerable water reserve – but what does it mean for people who live in water-scarce regions in Africa?A greater focus on water security for AfricaThe report helps us to understand more about nature’s way of storing water in aquifers – these are underground layers of porous rock that act like large sponges, allowing water to infiltrate the soil through pores and cracks. The water held in aquifers is known as groundwater.The new maps offer an accurate assessment of groundwater reserves, which are an important buffer to climate variability and change on the continent.Dr Anthony Turton, a South African scientist specialising in water resource management, agrees that there is an emerging trend in the global water sector to focus on groundwater resources.“The aquifers are a remarkable discovery and it is good news for South Africa,” Turton says. “If we can get the water out, it could substantially increase water availability on the continent,” he says.But Turton also has another idea – he thinks that the aquifers present great opportunities not only for water extraction, but also storage.“It is a good water security solution,” he says. “Instead of only seeing aquifers as a resource to pump water out of, we should pump water into them,” he says.Whether the problem is one of too little water over long periods of time, or too much water at once, the World Economic Forum on Africa has already flagged water security as one of the fastest-growing social, political and economic challenges today.Analysts predict that the demand for water in all sectors will increase. It is up to decision makers and water experts to find solutions to deal with the 40% global shortfall between expected demand and available supply by 2030.More than 300-million people in Africa don’t have access to safe drinking water and greater access to improved water supplies has become an international priority.Increasing the number of hectares under irrigation is another pressing issue. According to the report, only 5% of arable land is irrigated. There is a need to increase this figure to help meet the rising demands for food production to combat growing food insecurity.Where are the aquifers?The origin of the maps is an interesting story involving earth- penetrating radar, satellite cameras and the search for oil reserves.“Satellites have the capacity to map the earth to identify oil reserves,” Turton explains. “As the satellites detect oil in underground reservoirs, over the years they also pick up the presence of fresh water aquifers.”Drawing up the new maps was a major feat as areas of North, Central and West Africa didn’t have good quality maps. Where available, the new aquifer maps are based on an extensive review of available hydro-geological maps, but scientists also had to consult many individual studies.According to Helen Bonsor from the BGS, one of the authors of the paper, the greatest groundwater volumes are in large sedimentary aquifers in North African countries such as Libya, Algeria, Chad, Egypt and Sudan.Turton says South Africa and the SADC region also have large hidden underground water reserves. “There are about 12 to 15 aquifer systems, of which three are considered very important for the future.”“In South Africa a very substantial resource lies in a massive dolomite aquifer system east of Johannesburg in Gauteng,” he says.This aquifer covers a vast area, extending from Springs and Brakpan east of Johannesburg; to Lenasia south of the city; Zuurbekom, Carltonville and Magaliesberg on the West Rand; Kuruman in the Northern Cape and even as far as parts of Botswana.“To give you an idea of the size, the Witwatersrand mining basin’s aquifer storage capacity is about the size of Lake Kariba,” he says.Other countries such as Mozambique, Zambia, Zimbabwe, Namibia, Botswana and Ghana also have hidden aquifers.Getting the water outAlthough there is a lot of water underground the next big question is how to get it out, and if it is economically viable to extract it.The BGS paper points out that in certain areas, appropriately sited and developed boreholes for low-yielding rural water supply and hand pumps could be successful. However, the paper also warns that the potential for higher-yielding boreholes might not be possible.Extracting the water could also be very costly. “In many cases the water will have to be pulled up from a fairly great depth,” Turton says.Dr Alan MacDonald, lead author of the study, told BBC News that high-yielding boreholes should not be developed without a good understanding of local groundwater conditions.Large parts of Africa don’t receive rain very often and this means that many aquifers are not filled regularly. Scientists are concerned that aquifer water resources might be depleted if large-scale development of boreholes goes ahead.Turton points out that the logistics of mass extraction of water from aquifers is a big challenge. “So much cabling, piping and drilling will be needed, which will increase the cost of getting the water out.”However, he says large-scale drilling becomes more viable if the rock is very porous and has good transmissivity, a measure of the quantity of water that an aquifer can transmit horizontally.Transmissivity is also used to determine the water that an aquifer can deliver to a pumping well.“Highly transmissive systems are very suitable for exploitation,” he says.Aquifers for water storageTurton believes that extracting the water for use in hand pumps might not be the best option. “The true value of aquifers lie in their use for future storage of water,” he says.Underground storage is an efficient way to store water. The resource won’t be vulnerable to evaporation losses and it is fairly safe from contamination. Water found in aquifers is often cleaner than surface reserves because the permeable rock layers act as natural filters that purify water by removing impurities.Turton says in Africa the conversion ratio of rainfall to runoff is very low and a large amount of water is lost to evaporation.At continental level, the conversion rate is only 20% and in South Africa, the figure is even lower, between eight and 10%. In two of South Africa’s most important river basins, the Limpopo and Orange, the ratio is only 5%.“This has to be improved and aquifers are an excellent opportunity for this,” he says.The challenge from an engineering perspective is to find new ways to use ground water aquifers as underground storage dams.“Instead of storing water in dams above ground, water can be treated and stored underground to prevent large-scale evaporation. Building dams isn’t the only way to go,” he says.“It is possible to store water 200 to 300 metres underground for 25 years or even longer.”The idea presents many engineering challenges, but it is not impossible.A few years ago, the Department of Water Affairs in cooperation with the Water Research Commission, the Council for Scientific and Industrial Research, and Groundwater Africa, released a document about the possibility of developing a national artificial recharge strategy as part of the country’s water management planning.Artificial recharge (AR) is the process whereby surface water is transferred underground via boreholes and infiltration basis to be stored in an aquifer.When needed, the water can be pumped from the aquifers via boreholes to users. Locally, AR is an ideal way to promote water conservation.Turton says that South Africa can learn from Botswana’s example. The ministry of water in that country built many smaller dams on a river system to capture water in peak periods. The dams are designed to leak, allowing the water to seep naturally into the ground.“This type of development could attract investment into the country and we need more investment in the water sector to attract the technology we need to do this,” he explains.Source: Department of Water and SanitationWould you like to use this article in your publication or on your website? See Using Brand South Africa material.last_img read more


Tag: 成都桑拿网

first_imgA five-year-old girl, daughter of a migrant labourer, was brutally raped by unidentified men in Dasuya town in Hoshiarpur district, police said on Tuesday.The girl was admitted to the Civil Hospital, Dasuya from where she was referred to PGIMER, Chandigarh, in a critical condition after the incident on Monday night, they said.Police said the girl went missing from her house last night at about 10:30 p.m. when there was a power shutdown in the area. The family members lodged a missing report with the Dasuya police station late on Monday night. On Tuesday, a passer-by noticed the girl lying in an unconscious state near a railway track. Some blood stained clothes were also found there.The father of the girl is a migrant labourer, police said. Dr. Rajesh Bagga, Senior Medical Officer at Dasuya Civil Hospital, confirmed gang rape and said the victim suffered external as well as internal wounds. A case was registered at the Dasuya police station under relevant provisions of the POCSO Act and the IPC, police said.last_img read more


Tag: 成都桑拿网

first_imgOver 12 months after the gang rape of a minor girl near Kunduli in Koraput district and her subsequent death by hanging, no leader of any political party or social organisation has come forward to file an affidavit or testify before the Judicial Commission set up by the Odisha government to probe the case.The 15-year-old victim had alleged that on October 10, 2017, she was gang-raped by four men dressed as jawans of paramilitary forces near Kunduli. She had killed herself by hanging at her home in Musaguda on January 22 this year.On November 8, 2017, the government had ordered a judicial inquiry into the incident by a sitting district judge. A parallel enquiry by the State Crime Branch was also ordered. But to date the culprits have not been identified.Speaking to The Hindu, special counsel of the Judicial Commission, Prabhakar Patnaik, said the time period of the Commission ended on September 25 this year and, as per his knowledge, it has already furnished its report to the State government. Mr. Patnaik said no leader of any political party or social organisation came out to testify or provide evidence before the Commission.According to Mr. Patnaik, advertisements were published in two Odia and one English newspapers inviting documents and evidence from any stakeholder to be furnished before the Commission. Family members of the victim were witnesses of the Commission. Fifteen others, including police officers involved in the investigation of the case, doctors who treated the victim and the Koraput District Child Protection Officer testified before the Commission.last_img read more


Tag: 成都桑拿网

first_imgOTTAWA – Prime Minister Justin Trudeau heads to Washington Tuesday to further strengthen the ties between Canada and the U.S. just as a new poll suggests Canadians don’t want this country heading down the same path as its southern neighbour.But the results of the Ekos-Canadian Press survey don’t necessarily mean Canadians’ points of view are completely at odds with those who voted U.S. President Donald Trump into office, said Ekos president Frank Graves.Ekos and the Canadian Press surveyed 4,839 Canadians via telephone between Sept. 15 and Oct. 1 as part of an ongoing effort to understand whether the same drivers exist in Canada as those behind populist movements supporting a more isolationist viewpoint around the world.The results suggest Canada favours a more open approach — 60 per cent of those asked don’t want a “Canada First” foreign policy that mirrors the “America First” rallying cry that put Trump in office. Eighty per cent of those surveyed also disapprove of the way Trump is handling his job, and 52 per cent want to see Canada become less like the U.S.“Canada is clearly pivoting open, you can make the case with some of the data on that,” said Graves.“But if you look at more of the data, I’m not so sure. It’s not that clear.”The data also suggests 22 per cent of those surveyed think Canada ought to become more isolated, a marked increase after years of the number remaining relatively flat.Also, among those surveyed 37 per cent think Canada’s immigration policy admits too many visible minorities. Twenty-nine per cent said they’ve experienced an incident of racism in the last month, and 33 per cent said they believe racism is becoming more common.Ekos conducted the survey between Sept. 15 and Oct. 1, and the survey of the entire sample has a margin of error of plus or minus 1.4 percentage points 19 times out of 20.Different sample sizes were polled for each question to increase the number of questions researchers were able to ask.Ekos has been tracking attitudes towards visible minority immigration for 25 years because it serves as a way to test levels of racial intolerance in Canada, said Graves.The question of whether it is too high was put to 1,154 people during the recent survey, and the margin of error for those findings was 2.9 percentage points, 19 times out of 20.Forty-two per cent believe the right amount are being let in and 15 per cent say too few.Graves said the incidence of those believing it’s too high peaked before the last federal election and seems to be on the decline. It’s still lower than it was in the 1990s, he said.The survey also probed for people’s perceptions of their economic future, and the results suggest Canadians are pretty pessimistic about the way things are going, despite economic indicators to the contrary.That, coupled with the responses on how open this country ought to be, suggests the door can’t be closed on the argument that the same economic and social frustration that’s fuelled populism elsewhere doesn’t exist here, Graves said.“There’s clearly a significant portion of Canada that’s not going to be convinced by the whole notion that an open welcoming Canada is the right answer to the problems that they see in their lives and the country.”What that might mean for Canada’s political landscape remains to be seen. Sixty-four per cent of those who say Canada is letting in too many visible minorities identify as Conservative supporters; 62 per cent of those who think the number is just right are Liberal.But Graves noted that studies done in the U.S. before and after that election revealed that people who were exhibiting racial intolerance and who voted for Trump said they would have voted Democrat if that party had put forward a more progressive platform.Maintaining support for immigration ranks high on the Liberals’ list of priorities; in the coming weeks, they’re poised to unveil how many newcomers Canada will admit in 2018.The Liberals are keen on immigration to foster economic growth, but complicating the issue is the ongoing arrival of asylum seekers at the border prompting criticism the government has lost control of the system.In Britain, a survey after the surprising yes vote in a referendum on leaving the EU found that nearly 73 per cent of those who voted to leave were worried about immigration levels being too high.The Ekos survey found 41 per cent feel too many immigrants are currently being let in overall.last_img read more