Today, more than 700 million people around the world drink water from unsafe or untreated sources, 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 have access to safe drinking water.
Climate change is likely to worsen the situation 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 to measure water scarcity by using satellites hundreds of miles in space.
How to measure water scarcity
To estimate water scarcity, hydrologists, the people who study the science of water, build what they call a “water budget.”
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., the average person uses between 300 and 400 liters of water per day 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 less than 500,000 liters of water 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 population of 2.4 billion by 2050, 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. Read more…