<figure>
 <img decoding="async" src="https://images.theconversation.com/files/308779/original/file-20200107-123377-2bsrfa.jpg?ixlib=rb-1.1.0&#038;q=45&#038;auto=format&#038;w=754&#038;fit=clip" />
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 High resolution satellite image of the Nile River’s delta.
 Shutterstock/TommoT
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<a href="https://theconversation.com/profiles/ethan-d-coffel-389546">Ethan D. Coffel</a>, <a href="http://theconversation.com/institutions/dartmouth-college-1720">Dartmouth College</a> and <a href="https://theconversation.com/profiles/justin-s-mankin-930128">Justin S. Mankin</a>, <a href="http://theconversation.com/institutions/dartmouth-college-1720">Dartmouth College</a>

The Nile – the world’s longest river – runs through <a href="https://ascelibrary.org/doi/pdf/10.1061/9780784481394.026">11 countries</a> in Africa and <a href="https://www.internationalrivers.org/campaigns/nile-basin">has a basin</a> that covers about 3 million sq kms, nearly 10% of the continent’s landmass. About <a href="http://atlas.nilebasin.org/treatise/estimated-and-projected-total-population-in-nile-basin-countries/">250 million people</a> are reliant on the Nile’s waters in Ethiopia, Uganda, South Sudan, Sudan and Egypt. 

Nearly all of the rainfall that feeds the Nile’s two major tributaries – the Blue and White Nile – falls in the upper Nile basin, found in South Sudan, western Ethiopia and Uganda. The lower Nile basin receives very little rainfall and the countries there – Sudan and Egypt – depend heavily on the Nile for water. 

Climate projections suggest that, by the end of the century, the amount of rain in the Upper Nile basin could increase <a href="https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019EF001247">by up to 20%</a>. But our <a href="https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019EF001247">new paper</a> shows that, despite more rainfall, devastating hot and dry spells are projected to become more frequent in the Upper Nile basin. 

These conditions will occur simultaneously with the region’s rapid population growth, <a href="http://atlas.nilebasin.org/treatise/estimated-and-projected-total-population-in-nile-basin-countries/">anticipated</a> to double by the middle of this century. This will increase water stress in the region, irrespective of the modest rainfall increases.

At present, around 10% of the basin’s population faces chronic <a href="https://www.un.org/waterforlifedecade/scarcity.shtml">water scarcity</a> due to the region’s seasonal aridity and the highly unequal distribution of water resources. By 2040, according to our research – in a year with average temperatures and rain – the number of people facing water scarcity could reach 35%. That’s more than 80 million people without enough water to function in their daily lives.

Hot and dry conditions will make this worse. These conditions will kill crops, reduce hydropower, diminish the water available for people and industry and heighten tensions over the distribution of regional water resources. By 2040, a hot and dry year could push over 45% of the people in the Nile Basin – nearly 110 million people – into water scarcity. 

Even without these developments, population growth would drive water scarcity in the Upper Nile. But larger deficits in the amount of water flowing into streams and rivers during future hot and dry years will amplify this effect. This will leave an additional 5% to 15% of the future population in the Upper Nile basin facing water scarcity in hot and dry years.

These climate and population changes will project onto an already complex and tense socioeconomic and political landscape. 

The Nile’s 11 riparian states vie with one another for the river’s water. The downstream states of Egypt and Sudan try to assert control over the Nile flow, while upstream states try to find ways to secure water for their well-being. Coupled with the region’s strong dependence on subsistence agriculture and political instability, the region is at risk of severe food and water shortages. 

<h2>More hot and dry years</h2>

For our research, we wanted to understand how much more frequent hot and dry years could become, despite the slight increase in overall rainfall.

To do this we assessed historical climate trends in the Upper Nile Basin using eight observational data sets. These recorded rainfall and temperature in the Upper Nile basin between 1961 and 2005. We also used climate models to estimate how temperature and precipitation will change over the remaining century.

Our findings show that hot and dry years have become more common over the past four decades in the Upper Nile basin and that this trend is likely to continue. These hot and dry conditions will be similar to those that have resulted in crop failures, food shortages and humanitarian crises in the region over the past decades. 

By the late 21st century, the frequency of these hot and dry years may rise between a factor of 1.5 and 3. In the past, hot and dry years occurred about once every 20 years; but this increase in frequency means that in the future a hot and dry year could occur once every six to 10 years, making them a common experience for people in the region. 

In addition to becoming more frequent, they will also become more severe. Temperatures during heat waves in the region could rise between 2°C and 6°C, putting far more stress on people, animals and crops than occurs today.

We estimated the number of people facing water scarcity by comparing the total runoff – the amount of water flowing into streams and rivers – which is available for human consumption with the amount of water every person needs to meet their basic needs. When we make this comparison, we find that despite the small projected increase in rainfall, as the population rises and hot and dry years become more frequent, the total water supply will be far less than needed to meet the region’s needs.

<h2>Causes</h2>

What’s causing all this?

Like the rest of the world, the <a href="https://www.usaid.gov/sites/default/files/documents/1860/A%20Climate%20Trend%20Analysis%20of%20Ethiopia.pdf">Nile Basin region has been warming</a> due to rising global greenhouse gas concentrations. Because rainfall is projected to slightly increase in the region, the frequency of dry years won’t change significantly. However, the rise in temperature means that when dry years happen, they will be hot. 

Compounding this drying is a projected increase in the <a href="https://www.nature.com/articles/nclimate3273">year-to-year variations</a> in rainfall, which may be due to projected intensification of El Niño and La Niña cycles. This creates a <a href="https://www.nature.com/articles/s41558-018-0140-y">precipitation “whiplash”</a> in the region, where severe <a href="https://reliefweb.int/report/sudan/islamic-relief-responds-flash-floods-devastate-white-nile-sudan">wet</a> and <a href="https://www.hydrol-earth-syst-sci.net/18/1239/2014/">dry</a> years occur in quick succession. 

<h2>What can be done</h2>

One critical priority is to ensure that food and water are more equally available to all. Despite there being enough food and water on average, many people <a href="https://www.usaid.gov/sites/default/files/documents/1866/09.30.19_-_USAID-DCHA_Ethiopia_Complex_Emergency_Fact_Sheet_3.pdf">cannot afford or access it</a>. This will get worse.

A critical first step is for basin states to create an equitable water allocation scheme among them that not only addresses “historical rights” – such as Egypt’s long-held claims to <a href="https://www.tandfonline.com/doi/full/10.1080/03932729.2017.1333272">two-thirds of Nile flow</a> – but also to the needs of upstream countries like South Sudan and Ethiopia, which require water to build their economies. 

Cooperative water-sharing institutions within the basin could help avert contentious situations. For instance, Ethiopia is currently constructing the <a href="https://www.reuters.com/article/us-ethiopia-dam-factbox/factbox-key-facts-about-ethiopias-giant-nile-dam-idUSKBN1XG21L">Grand Ethiopian Renaissance Dam</a> on the Blue Nile River. Without strong regional institutions to provide political and legal assurances of fair Nile water use, the dam’s construction is provoking worries in Egypt, as it would likely reduce irrigation water availability for the country’s agriculture.

Water may be often pointed to as a source of conflict, but as with the case of <a href="http://www.columbia.edu/%7Etmd2118/situstudio/why_cooperation.pdf">Israel and Jordan</a>, it can also be a means to cooperation, getting nations to the negotiating table. In a future world with more people and less water, countries in the Nile Basin will need to work together to ensure the best use of the region’s resources to catch and store rainfall in the wet, flood risk years, and equally distribute that water in dry years. 

If the region’s governments fail to work together to prepare, the consequences for their people could be catastrophic.<img loading="lazy" decoding="async" src="https://counter.theconversation.com/content/129360/count.gif?distributor=republish-lightbox-basic" alt="The Conversation" width="1" height="1" style="border: none !important; box-shadow: none !important; margin: 0 !important; max-height: 1px !important; max-width: 1px !important; min-height: 1px !important; min-width: 1px !important; opacity: 0 !important; outline: none !important; padding: 0 !important; text-shadow: none !important" />

<a href="https://theconversation.com/profiles/ethan-d-coffel-389546">Ethan D. Coffel</a>, Neukom Institute Postdoctoral Fellow, <a href="http://theconversation.com/institutions/dartmouth-college-1720">Dartmouth College</a> and <a href="https://theconversation.com/profiles/justin-s-mankin-930128">Justin S. Mankin</a>, Assistant Professor, Department of Geography, <a href="http://theconversation.com/institutions/dartmouth-college-1720">Dartmouth College</a>

This article is republished from <a href="http://theconversation.com">The Conversation</a> under a Creative Commons license. Read the <a href="https://theconversation.com/in-the-future-there-will-be-more-rain-but-less-water-in-the-nile-basin-129360">original article</a>.

Nile_River_Shutterstock_TommoT

In the future there will be more rain but less water in the Nile Basin, what can be done?

By Lincoln
Wilcox and Efosa Ojomo



The United
Nations defines access to safe drinking water as a basic human right, but
according to their newest report, three out of ten—or 2.1 billion people—still
lack access to it. Water may be life, but unfortunately it’s not free.&nbsp;



Governments
and development organizations have spent billions of dollars over the past
several decades in an attempt to address this inequity in low- and
middle-income countries, but the unfortunate reality is that many of these
efforts have fallen flat. The United States, for example, has spent more than <a href="https://www.theguardian.com/society/katineblog/2009/mar/26/water-projects-wasted-money">$360
million</a> on rural water supply schemes in Africa and other regions that have
broken down and no longer work. When outside actors provide communities with
resources like wells and water treatment infrastructure, too often no
sustainable mechanism exists to maintain them. And even if they don’t break
down, donated solutions are inherently unscalable.&nbsp;



So how do
you create a solution that sticks? In our research, we&#8217;ve found that it starts
with innovators and entrepreneurs who create robust markets that serve people
who are currently unable to access water. These new markets provide the
necessary resources to make safe water not only affordable and accessible, but
also financially sustainable since they generate revenue that can then be used
to maintain and grow the market. Consider how these two organizations, each
with different business models, have created viable, lasting solutions that
address the access to water challenge in the regions where they operate.



Drinkwell:
Developing technology for safe water



In the
densely populated nation of Bangladesh, the country’s clean water <a href="https://www.who.int/bulletin/archives/78%289%291093.pdf">crisis</a> reached
an all-time high when it was discovered that arsenic had contaminated the
nation’s groundwater. It was this crisis that inspired Minhaj Chowdhury to form
<a href="http://drinkwellsystems.com/">Drinkwell</a>, a social enterprise that
sells low-cost, high-efficiency water filtration systems to local entrepreneurs
who build a business around providing safe water.



Empowering
entrepreneurs who can leverage their social capital to reach customers is a key
component of the company’s model, which Chowdhury credits with its
sustainability. But the company also ensures the long-term viability of its
“Water ATMs” by providing entrepreneurs with maintenance support and financial
management assistance.&nbsp;



Drinkwell
started selling its solution in 2013, but unlike to thousands of donated wells
that have provided water for limited periods before breaking down, the
organization’s financially sustainable model shows no signs of decay. To date,
more than 200,000 people now load “water credits” onto their DrinkWell cards
and use them at designated DrinkWell sites in India, Bangladesh, Laos, and
Cambodia, and the organization aims to expand its network to serve more than
5,000 communities in the next year. Drinkwell’s success offers a blueprint for
closing the gap on access to clean, affordable water.&nbsp;



Manila
Water: A public-private partnership that works



25 years
ago, as many as ten million people in the Philippines didn’t have access to
safe water. In the eastern region of Manila, the capital city, barely a quarter
of people had access to potable water. The situation got so bad that the
government was compelled to enact a National Water Crisis Act, which paved the
way for innovators to work with the government to solve this problem. This gave
birth to <a href="https://www.manilawater.com/corporate/about-us/our-story">Manila
Water</a>, a public-private partnership between the government and the
Philippines&#8217; oldest conglomerate, Ayala Corporation.&nbsp;



As a
private company, Manila Water had a strong incentive to distribute water to as
many customers as possible. To do this, its executives invested in new systems
for production, treatment, and distribution of water; trained an entirely new
workforce; and reshuffled the existing organization structure to focus on
increasing access. At the same time, the government retained its ability to
regulate the industry to best serve the people of Manila. This hybrid
public-private relationship between Ayala and the government has paid off
immensely as more than 99% of people in the region now have access to
affordable, clean water. In addition, Ayala is exporting its expertise to
neighboring countries, including Vietnam, Thailand, Myanmar, and Indonesia.
Sometimes the government has the will, but the private sector might just have
the way.



In a world
where water, the most basic resource we need to survive, is still out of reach
for more than two billion people, a fundamental rethinking of how we address
the challenge of providing this critical resource is necessary. No one
organization can solve the global water challenge, but organizations like
Drinkwell and Manila Water have shown a way to develop innovative
models—through leveraging entrepreneurship, new technologies, and government
partnerships —to tackle this seemingly intractable issue. And unlike more
conventional answers to the problem, these solutions are fundamentally
sustainable and scalable. That’s why they remain our best hope for making water
accessible to all.



Lincoln
Wilcox is a
research associate on the global prosperity team at the Clayton Christensen
Institute.



Efosa Ojomo is a senior research fellow at the
Clayton Christensen Institute where he leads its Global Prosperity research.

Op-Ed: The best hope for solving the global water crisis

By <a href="https://theconversation.com/profiles/meron-teferi-taye-804226">Meron Teferi Taye</a>, <a href="http://theconversation.com/institutions/addis-ababa-university-2161">Addis Ababa University</a> and <a href="https://theconversation.com/profiles/ellen-dyer-804257">Ellen Dyer</a>, <a href="http://theconversation.com/institutions/university-of-oxford-1260">University of Oxford</a>

In July Ethiopians <a href="http://www.unenvironment.org/news-and-stories/story/ethiopia-plants-over-350-million-trees-day-setting-new-world-record">planted</a> 350 million trees in a single day. This was part of the country’s national <a href="https://pmo.gov.et/greenlegacy/">green legacy initiative</a> to counter environmental degradation and climate change. The initiative ultimately aims to grow 4 billion trees across the country.

Ethiopia has long struggled with land degradation problems in part caused by <a href="https://www.thegef.org/topics/land-degradation">unsustainable agricultural practices</a> – like <a href="https://link.springer.com/chapter/10.1007/978-3-319-19168-3_14">vegetation clearance and overgrazing</a>, among others. These pressures are increasing as the population grows.

Where water becomes scarcer due to climate change, <a href="https://www.longdom.org/open-access/climate-change-and-its-impact-on-land-degradation-imperative-need-to-focus-2332-2594.1000108.pdf">land degradation could worsen</a>. But what does the science tell us about the effects of climate change on water resources, and so on people and the economy, in Ethiopia?

Since 2015, the <a href="https://reachwater.org.uk/">REACH programme</a> – a global research programme to improve water security for the poor and in which we are involved – has attempted to answer this question. We focused on Ethiopia’s Awash River basin, one of the country’s most economically and socially important basins.

The basin represents about <a href="https://www.researchgate.net/publication/265483628_The_Water_of_the_Awash_River_Basin_a_Future_Challenge_to_Ethiopia">10% of the country’s land area</a>, and 17% of its total population. It is home to the capital city, Addis Ababa, and also plays a critical role for Ethiopia’s economy.

In Ethiopia, most studies on the effects of climate change on water resources focus on the Nile basin. Future projections also often lack consistency because of the differences in the models that are used. <a href="https://reachwater.org.uk/resource/climate-change-impact-on-water-resources-in-the-awash-basin-ethiopia/">Our research</a> aimed to develop better estimates of the effects of climate change on water availability in the Awash basin. We did this by using climate models that best represented the region’s characteristics. 

We found that, in the future, the basin will be hotter, drier and more water stressed. This could have severe consequences on human and economic development, highlighting the need for climate resilient policies to minimise impacts.

<h2>Water is crucial for people and the economy</h2>

In Ethiopia, rainfall and water availability are highly variable. The lack of water often impacts communities, industry and agriculture. Almost all food crops, and most industrial crops in Ethiopia, are <a href="http://www.fao.org/nr/water/aquastat/countries_regions/eth/ETH-CP_eng.pdf">produced by rain-fed agriculture</a>. Industrial crops alone contribute to <a href="https://www.undp.org/content/dam/ethiopia/docs/UNDP%20Ethiopia%20Fact%20Sheet%20-%20Agriculture%20Growth%20and%20Transformation%20-%20August%202014.pdf">85% of export earnings</a>.

In addition water is vital to electricity generation. Hydropower accounts for about <a href="https://www.hydropower.org/country-profiles/ethiopia">90% of Ethiopia’s electricity</a>. 

This high reliance on water means that Ethiopia is very vulnerable to water-related climate shocks – like water scarcity, drought and floods. <a href="https://reachwater.org.uk/resource/water-resources-extreme-events-awash-basin-economic-effects-policy-implications/">A modest 5% decrease in rainfall</a> could cause a 10% decrease in agricultural productivity and reduce the GDP derived from the basin by 5%.

The basin is already vulnerable. It often experiences floods and droughts. Besides, access to water is very geographically uneven, with rainfall and surface water being scarce downstream and relatively abundant in the highlands. To what extent would adding climate change to the mix worsen the situation?

<h2>Hotter and drier future</h2>

Using models that best characterise the basin, we projected future changes in temperature and precipitation. We then compared those to the historical average. Our climate projections suggest water stress will generally intensify in the future – although there are some spatial differences. Water availability will continue to decrease progressively until at least the end of the century.

These findings are particularly critical for the key irrigation period of April to June. During these months we find decreasing precipitation and increasing temperature will lead to lower water availability. 

These months are the peak irrigation period for both small-scale farmers and large-scale irrigators. Additionally, water allocation between hydropower and irrigators could be a source of conflict in the face of decreased water availability.

Finally, this will make water access more challenging for human needs such as drinking, sanitation and hygiene. This will be particularly true for poor and vulnerable communities, and those downstream.

<figure>
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<h2>Climate resilient policies</h2>

Developing climate resilient policies for allocating water, and planning for a reduced water availability, is ever more pressing. But incorporating climate information within management decisions is a complex task. This requires access to scientific information and a good understanding of the current and future hydroclimatic situation.

To support better water management and allocation policies, our research points to the need to:

<ul>
<li>Improve the accessibility of climate information and develop the capacity of staff in government and related institutions to be able to understand and use it for water management; </li>
<li>Sustainably develop additional water sources, such as groundwater, which could act as a buffer and supplement surface water supply;</li>
<li>Consider the needs of the poorest in the basin who are the most vulnerable to climate change.</li>
</ul>

Of course, decisions about how much water to allocate and to whom in a drier future will be politically challenging. They require effective management strategies, political will and investments and better stakeholder dialogue forums. Scientists will also need to work more closely with policy makers.

Ethiopia’s green legacy is a promising contribution towards tackling global climate change: trees can play an important role in removing atmospheric carbon dioxide. But can trees contribute to local climate adaptation and mitigate land degradation? 

This is a complex question and our view is that, for a country that will likely be hotter, drier, and more water stressed, climate resilient policies need to be grounded in robust science.

Alice Chautard, REACH Communications and Knowledge Exchange Manager, University of Oxford, contributed to the writing of this article.<img loading="lazy" decoding="async" src="https://counter.theconversation.com/content/121844/count.gif?distributor=republish-lightbox-basic" alt="The Conversation" width="1" height="1" style="border: none !important; box-shadow: none !important; margin: 0 !important; max-height: 1px !important; max-width: 1px !important; min-height: 1px !important; min-width: 1px !important; opacity: 0 !important; outline: none !important; padding: 0 !important; text-shadow: none !important" />

<a href="https://theconversation.com/profiles/meron-teferi-taye-804226">Meron Teferi Taye</a>, Country Programme Manager, REACH: Improving Water Security for the Poor, <a href="http://theconversation.com/institutions/addis-ababa-university-2161">Addis Ababa University</a> and <a href="https://theconversation.com/profiles/ellen-dyer-804257">Ellen Dyer</a>, Postdoctoral researcher in African Climate Science, School of Geography and the Environment, <a href="http://theconversation.com/institutions/university-of-oxford-1260">University of Oxford</a>

This article is republished from <a href="http://theconversation.com">The Conversation</a> under a Creative Commons license. Read the <a href="https://theconversation.com/ethiopias-future-is-tied-to-water-a-vital-yet-threatened-resource-in-a-changing-climate-121844">original article</a>.

This East African country’s future is tied to water – a vital yet threatened resource in a changing climate

By <a href="https://theconversation.com/profiles/emad-hasan-773516">Emad Hasan</a>, <a href="http://theconversation.com/institutions/binghamton-university-state-university-of-new-york-2252">Binghamton University, State University of New York</a> and <a href="https://theconversation.com/profiles/aondover-tarhule-773518">Aondover Tarhule</a>, <a href="http://theconversation.com/institutions/binghamton-university-state-university-of-new-york-2252">Binghamton University, State University of New York</a>

Today, more than 700 million people around the world <a href="https://www.who.int/news-room/fact-sheets/detail/drinking-water">drink water from unsafe or untreated sources</a>, such as wells, springs and surface water. 

About half of these people live in sub-Saharan Africa. In fact, in more than 30 African countries, fewer than 20% of the people <a href="https://thewaterproject.org/water-scarcity">have access to safe drinking water</a>. 

<a href="https://www.ipcc.ch/site/assets/uploads/2018/03/climate-change-water-en.pdf">Climate change is likely to worsen the situation</a> by making water less available in some locations and by changing the amounts and timing when water is available. 

Determining whether a region has sufficient water to satisfy the needs of people who live there is a complicated and imperfect process. Our research team has developed a new approach <a href="https://doi.org/10.3390/rs11080904">to measure water scarcity</a> by using satellites hundreds of miles in space. 

<h2>How to measure water scarcity</h2>

To estimate water scarcity, hydrologists, the people who study the science of water, build what they call a <a href="https://naturalsciences.ch/topics/water/water_balance">“water budget.”</a> 

They estimate all of the water entering the country – from rivers, rainfall, groundwater and man-made sources – and then subtract all of the water exiting the country. This produces an estimate of the available water in the country or region. 

By dividing the available water by the population in the region, hydrologists can tell whether there is sufficient water to meet people’s needs. 

Generally, in the U.S., <a href="https://water.usgs.gov/edu/qa-home-percapita.html">the average person uses between 300 and 400 liters of water per day</a> for basic needs – like drinking, sanitation, bathing and food preparation. 

Globally, a country is said to experience a serious water scarcity problem if it has <a href="http://www.fao.org/nr/water/aquastat/maps/TRWR.Cap_eng.pdf">less than 500,000 liters of water</a> per person per year, to meet both their daily needs and agricultural needs.

This water budget process works if accurate data are available for each source of water. However, in many developing regions, such as Africa, the data required to calculate water budgets are not available. 

Yet Africa critically needs accurate information on its water scarcity status. As the second most populated continent, Africa is projected to have <a href="https://www.prb.org/2013-world-population-data-sheet/">a population of 2.4 billion by 2050</a>, approximately double the current estimated population. Such rapid population growth will exert considerable stress on the continent’s available water resources, worsening the already acute water scarcity situation. 

So, assessing the potentially available water resources is essential for the future.

<h2>Look to the skies</h2>

<a href="https://doi.org/10.3390/rs11080904">Our study</a> takes a new approach to assessing water scarcity. 

We used data from two satellite systems. The first is called the Tropical Rainfall Measuring Mission, operated since 1997 by the U.S. and Japan. The Tropical Rainfall Measuring Mission uses several instruments – including a precipitation radar, microwave imager, visible and infrared scanner – to estimate rainfall. Getting the rainfall estimate right is critical, because this is the most important source of water for human use. 

The second type of satellite data is from the Gravity Recovery and Climate Experiment, a joint mission between the U.S. and Germany. First launched in 2002, the Gravity Recovery and Climate Experiment is a twin satellite mission that uses the changes in the Earth’s gravitational fields to infer changes in the global water resources, from the Earth’s surface to the deepest groundwater aquifers. 

We combined data from these two satellite systems to calculate the monthly potential available water from all sources of water for each country in Africa from 2002 to 2016. By dividing this value by the population in each country, we obtained a new measurement of available water storage per capita. 

Because the Gravity Recovery and Climate Experiment satellite data also estimates water in deep groundwater aquifers, which may not be accessible due to technical or economic limitations, we refer to this new estimate as potential available water storage.

<figure class="align-center zoomable">
 <a href="https://images.theconversation.com/files/283755/original/file-20190711-173347-18a9z4h.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=1000&amp;fit=clip"><img decoding="async" alt="" src="https://images.theconversation.com/files/283755/original/file-20190711-173347-18a9z4h.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" srcset="https://images.theconversation.com/files/283755/original/file-20190711-173347-18a9z4h.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=600&amp;h=241&amp;fit=crop&amp;dpr=1 600w, https://images.theconversation.com/files/283755/original/file-20190711-173347-18a9z4h.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=600&amp;h=241&amp;fit=crop&amp;dpr=2 1200w, https://images.theconversation.com/files/283755/original/file-20190711-173347-18a9z4h.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=600&amp;h=241&amp;fit=crop&amp;dpr=3 1800w, https://images.theconversation.com/files/283755/original/file-20190711-173347-18a9z4h.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;h=303&amp;fit=crop&amp;dpr=1 754w, https://images.theconversation.com/files/283755/original/file-20190711-173347-18a9z4h.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=754&amp;h=303&amp;fit=crop&amp;dpr=2 1508w, https://images.theconversation.com/files/283755/original/file-20190711-173347-18a9z4h.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=754&amp;h=303&amp;fit=crop&amp;dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
 <figcaption>
 Potentially available water per capita, for present-day (A) and future estimates for the year 2025 (B) and 2050 (C).
 <a class="source" href="https://doi.org/10.3390/rs11080904">Remote Sensing (2019)</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a>
 </figcaption>
 </figure>

<h2>Measuring water, faster</h2>

We compared our results with the data currently used by the <a href="http://www.fao.org/nr/water/aquastat/data/query/index.html?lang=en">United Nations Food and Agricultural Organization</a>. Their method relies on conventional water budget accounting to estimate the total renewable water resources in a country. It then classifies each country into one of four categories: water-sufficient, vulnerable, water-stressed or water-scarce. 

Of the 48 African countries studied, our method classified 26 in the same category as the U.N.‘s method; 12 were classified as having more water than indicated and 10 as less. 

These differences are not surprising. Our estimate includes also water in aquifers deep underground that the U.N.’s method does not account for. Their method likely underestimates the total available water for countries that have substantial groundwater reserves. 

On the other hand, the accuracy of our method can be affected by the size of a country. Countries smaller than the Gravity Recovery and Climate Experiment footprint – the approximately 200,000 square kilometer blocks that the Gravity Recovery and Climate Experiment estimates can be made with confidence – are much more likely to be in error.

By 2050, assuming no change in available water resources, we project that 19 countries in Africa will face water scarcity and another nine countries will be water-stressed. However, if climate change were to cause Africa’s water resources to decrease by 10%, which is <a href="https://www.ipcc.ch/site/assets/uploads/2018/02/WGIIAR5-Chap22_FINAL.pdf">within the range of several climate projections for some African countries</a>, then approximately 85% of Africa’s population will experience a dangerous water scarcity situation. 

In general, we think that our method has several advantages over existing methods. It circumvents many of the limitations related to data unavailability and reliability in Africa. The data are more temporally and spatially continuous, as well as easier for researchers to access. As a result, estimates of water scarcity can be carried out much more rapidly for the entire continent. 

Satellites will gather new data in the coming years. We plan to take advantage of such data improvements as they become available to refine our method in terms of accuracy and water scarcity assessment at the sub-country level, not only in Africa but globally. 

[ Deep knowledge, daily. <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&amp;utm_medium=inline-link&amp;utm_campaign=newsletter-text&amp;utm_content=deepknowledge">Sign up for The Conversation’s newsletter</a>. ]<img loading="lazy" decoding="async" src="https://counter.theconversation.com/content/120055/count.gif?distributor=republish-lightbox-basic" alt="The Conversation" width="1" height="1" style="border: none !important; box-shadow: none !important; margin: 0 !important; max-height: 1px !important; max-width: 1px !important; min-height: 1px !important; min-width: 1px !important; opacity: 0 !important; outline: none !important; padding: 0 !important; text-shadow: none !important" />

<a href="https://theconversation.com/profiles/emad-hasan-773516">Emad Hasan</a>, Postdoctoral Researcher in Geography, <a href="http://theconversation.com/institutions/binghamton-university-state-university-of-new-york-2252">Binghamton University, State University of New York</a> and <a href="https://theconversation.com/profiles/aondover-tarhule-773518">Aondover Tarhule</a>, Vice Provost and Dean of the Graduate School, <a href="http://theconversation.com/institutions/binghamton-university-state-university-of-new-york-2252">Binghamton University, State University of New York</a>

This article is republished from <a href="http://theconversation.com">The Conversation</a> under a Creative Commons license. Read the <a href="https://theconversation.com/we-use-satellites-to-measure-water-scarcity-120055">original article</a>.

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