New analysis using the World Resources Institute’s water risk tool has identified eighteen of the world’s most water-stressed rivers.
Ahead of World Water Day on 22nd March, WRI analyzed the top 100 river basins by population and found 18 river basins that face the highest water stress, including the Colorado and Rio Grande (United States), Yellow River (China), and the Indus (Pakistan, China and India). These river basins withdraw over 80 percent of their available water annually.
The analysis follows Aqueduct’s country water-stress rankings (released December 2013) that identified the top water risk hotspots worldwide. Both rankings were developed using WRI’s global water risk mapping platform, Aqueduct.
The world’s 100 most-populated river basins are indispensable resources for billions of people, companies, farms, and ecosystems – but many of them are also increasingly at risk.
As water demand from irrigated agriculture, industrialization, and domestic users explodes, major rivers on several continents are becoming so depleted that they sometimes fail to reach their ocean destinations.
According to WRI's Andrew Maddocks and Paul Reig, when climate change, nutrient and chemical pollution, and physical alterations like dams and other infrastructure development are added to the mix, many communities which rely on water resources are facing an increasingly risky future.
WRI’s Aqueduct project recently evaluated, mapped, and scored stresses on water supplies in the 100 river basins with the highest populations, 100 largest river basins, and 180 nations.
The analysis found that 18 river basins— flowing through countries with a collective $US 27 trillion in GDP —face “extremely high” levels of baseline water stress. This means that more than 80 percent of the water naturally available to agricultural, domestic, and industrial users is withdrawn annually—leaving businesses, farms, and communities vulnerable to scarcity.
River basin management plans deliver mixed results
According to WRI, decision-makers in many of world’s water-stressed basins have attempted to put management plans in place—with mixed results. The United States’ Colorado River is cited as a prime example of a plan that, while well-intentioned, may ultimately be unsustainable.
Starting in Colorado and running 1,400 miles to the Gulf of California, the Colorado River is the 14th most stressed among the world’s most populated river basins, and the sixth most stressed if ranked by size.
The Colorado has become one of the most physically and legally managed rivers in the world. The imbalance between supply and demand means that the river often runs dry before it reaches the Pacific Ocean—posing significant problems for wildlife, ecosystems, and communities that depend on it.
WRI said the complex web of infrastructure and governance structures around the river was, in a sense, created to ensure predictable, steady water supplies in a stressed region. However, that same development has driven increasing demands for limited supplies.
Aqueduct’s country and river basin rankings deliberately do not include the effects of such extensive management, instead focusing on objective measures of underlying hydrological conditions. Maddocks and Reig say the overall picture is clear: Even the most-established, iron-clad management systems start to crumble under increasing scarcity and stress.
Global river basin data set to play increasingly role in managing water risks
Aqueduct’s stress scores and rankings provide a valuable common foundation for stakeholders to manage water-related risks.
Standardized scores help all stakeholders—from governments to development banks to civil society organizations—understand the nature of water security challenges and their potential social, economic, and environmental effects. The information is vital for making better, high-level decisions about where and how to begin to respond to river basin-level risks.
For companies, standardized scores inform better decisions about responding to basin-level hazards. Sustainability managers or operations supervisors know they are comparing each of their facilities in different basins around the world to the same standard. WRI said investors likewise benefit by the ability to more accurately compare water risks among their portfolio companies.
Shareholders, governments, civil society groups, and others also stand to gain when companies report river basin stress rankings. CDP’s water questionnaire – the leading corporate water risk disclosure platform –asks companies to disclose their water-risk exposure at the river-basin level.
As the world seeks to become more knowledgeable about water security threats, river basin-level water risk data looks set to play an increasingly key role in moving toward a water-secure future.