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Water Risks are Growing; Here’s a Tool to Help Us Prepare

January 29, 2016

Map of seasonal and dry-year depletion for 15,091 watersheds worldwide. The inclusion of season and dry-year depletion estimates increases by 15-fold the number of watersheds experiencing depletion of 75% or more. Source: Kate A. Brauman et al., in Elementa, January 20, 2016.

This map shows annual, seasonal and dry-year depletion for 15,091 watersheds worldwide. The inclusion of seasonal and dry-year depletion estimates increases by 15-fold the number of watersheds experiencing depletion of 75% or more. Source: Kate A. Brauman et al., in Elementa, January 20, 2016.

Earlier this month, the World Economic Forum in Davos, Switzerland, released its annual risk assessment, which looks across the spectrum of threats to society and ranks them. This year, it declared water crises to be the top global risk to society over the next decade.

Just behind water crises were the failure to adapt to climate change, extreme weather events, food crises and profound social instability. Together, these five threats constitute an interwoven risk landscape that has water shortages, in one way or another, at its core.

The Forum is not predisposed to emphasize environmental concerns. Terrorism, fiscal crises and the spread of infectious diseases are among the risks it considers and ranks. The Forum’s members include heads of state, chief executive officers and civic leaders.

Water topped one of the risk categories in the 2015 assessment, as well.

If an alarm bell was needed to focus global attention on water security, it has rung.

Last week, a team of colleagues and I released a new tool to help planners and policy-makers better understand the geography and nature of water risks around the globe. Our work was published in the journal Elementa: Science of the Anthropocene.

Our tool, though developed with some complex modeling, is represented by a very straightforward global map that depicts the depletion of water at a high degree of spatial resolution. (By “depletion,” we mean the fraction of renewable surface water and groundwater available in a watershed that is consumed by human activities.) This tool differs from most others available in two important ways.

Whereas most scarcity maps examine trends at the scale of large watersheds – sometimes even as big as the entire Mississippi River basin, which drains 40 percent of the continental United States – our tool breaks the picture down to much smaller sub-watersheds. This enables users to get a more detailed and accurate picture of where problems of shortage are likely to arise.

Second, instead of depicting water scarcity only as an annual average problem, it sketches out where seasonal and dry-year shortages can be expected. The inclusion of these periodic episodes of depletion increases by a factor of 15 the number of watersheds experiencing 75 percent depletion or more.

We found that in two-thirds of the world’s river basins, water consumption remains within sustainable limits. But in the other third, water extractions are heavily depleting available supplies. In those areas, freshwater ecosystems and the species they support are likely in trouble, and shortages impacting farms, cities and businesses are more likely to occur.

Because growing crops requires a great deal of water, watersheds with extensive irrigated agriculture tend to be at higher than normal risk for shortages. Some 40 percent of the world’s food comes from the 18 percent of cropland that is irrigated, so threats to irrigated agriculture can quickly translate into threats to global food security.

Our study characterizes 71% of world-irrigated area and 47% of large cities as experiencing at least periodic water shortage.

While no tool can serve as a crystal ball, this one helps remove some uncertainties by pinpointing areas at risk. This can help farmers, city planners, conservationists and businesses take steps to build more resilience and security in the face of prospective shortages.

It can highlight, for example, where it could make sense to institute “dry-year options,” whereby a city might pay irrigators to improve irrigation efficiency in return for the water saved. Or it might help conservation groups target where water banks might be needed to secure flows for rivers and wetlands.

Kate Brauman, lead scientist of the Global Water Initiative at the University of Minnesota’s Institute on the Environment, led our study team. Martina Flörke and Marcus Malsy from the Center for Environmental Systems Research at the University of Kassel in Germany anchored the heavy-duty modeling work, using the WaterGAP 3 global water resources model. Brian Richter, chief scientist at the global freshwater program of The Nature Conservancy and I completed the team of analysts and co-authors.

The map and water depletion data for all 15,091 watersheds are freely available at www.earthstat.org.

Originally published at National Geographic Newswatch.

  • timedonkey

    The Water Crisis, A Practical Solution
    The Water crisis is the most serious problem humanity has ever faced. Water pollution has infused the entire
    food chain with neurotoxins, poisons and pharmaceuticals, all of which damage the health and survivability of man and planet.
    The cause is our modern, water based sewer system. We flush all of our disposables down the drain, into the sewer system where more chemicals are added and then finally pumped back into our water system. Water based sewer systems are the prime polluters and our use of them has proved to be full of unintended and
    unanticipated horrors. The use of water based sewer system wastes and contaminates the entire water supply with pollutants and nutrients that if captured and recycled, could provide sufficient agricultural nutrients to ensure a sustainable food supply.
    One practical solution to the water shortage is to replace our centralized water based sewer system with
    on site, waterless toilets and to recycle grey water. Grey water is the water from the kitchen and shower and can be recycled, on site and reused for landscaping. This will reduce our demand on the water source by 80 percent while simultaneously creating a sustainable, renewable, agricultural resource, namely, organic nitrogen.
    No Mix toilets collect urine and feces in separate places, the toilet bowl has two drains, one, in the front
    for the urine and one in the back for the feces. The feces are dry composted and the urine is processed for agricultural purposes. Separating toilets protect the water supply and provide a renewable, safe, low cost source of nitrogen, enough to greatly reduce our dependence on foreign natural gas and oil. The
    important key is to separate the valuable, nitrogen rich urine, human urine is 18% organic nitrogen, at the source, before it is mixed with feces and before it is flushed into the water supply.

    The economic potential of capturing human urine is stunning. Human urine is 18% organic nitrogen and has
    been used in agriculture for thousands of years. Sweden, Germany, Holland and many other countries have been using and processing human urine for agricultural purposes and to protect the environment from water based sewer systems. Human urine is the only renewable, sustainable and economically feasible
    source of nitrogen available to humanity and it is free.

    What is the economic value of human urine? Here is how it works, the value of comparative petroleum
    derived fertilizer with the same 18% nitrogen content is approximately $10.00 a gallon and requires a massive polluting industry that is not renewable. The average person produces 2 liters of urine a day or roughly $5.00 worth of organic nitrogen. A city like Miami flushes down the drain 10 to 20 million dollars worth of nitrogen a day and spends another fortune to do it. Integrated Recycling is the future of our economy and could replace taxation in funding community services.The cities will become fertilizer factories and urban and suburban farming and food production could provide a sustainable, local food supply. Schools and churches could be nurseries and local gardening centers, hubs of city and urban agriculture and recycling. This could be a sustainable, local system that is a renewable doable foundation for local economies. Local food production is the basis of all economies and the missing component in modern cities.

    This kind of integrated recycling is highly profitable and turns three life threatening problems, water shortage, water pollution and imported oil into one sustainable, environmentally positive and economically beneficial solution.
    Water based sewer systems unnecessarily wastes and pollutes our most valuable resource, clean water. There is only one water supply for the entire earth. We share this single resource with 6.5 billion other humans and with all living organisms. Water should be regarded as our most important natural resource and shared birthright. Water is the first thing mankind must agree to share according to the highest collective principle. Water is the tie that binds us together, for better or for worse. Water is the blood of the earth and a true sacrament, something we all share, something that is absolutely necessary for life. We should not pollute the water supply with chemicals, insecticides or human disposables that can and should be recycled to
    insure a healthy and sustainable future.

    Modern, water based sewer
    systems could be the worst idea mankind has ever adopted. Common sense informs us not to defecate in the drinking water but that is exactly what we currently do in every city of the land. We do it without thinking. That is the problem. We are not thinking right. It is possible, conceivable, that the water crisis could be THE reason people begin to think of ourselves as truly united with everyone else on the planet, known and unknown, united in our fears, hopes and desires. 6.5 billion Separate destinies have become one destiny for us all. Universal Birthright ….

  • timedonkey

    what happened to my comment?

  • postcarbon

    All comments must be approved by moderators (only spam and abusive comments are not approved) – this is usually within a 24-hour turnaround but sometimes the lag time is longer if it’s a weekend or we are out of the office. Your comment has been posted.