Modern water infrastructure is a lot of concrete: dams, canals, reservoirs. But as the world warms and population grows, those old approaches won’t be enough to stave off drinking-water catastrophe, according to a 100-page United Nations report released this week. Humanity will have to start embracing techniques that mimic natural processes.
“For too long, the world has turned first to human-built, or ‘grey,’ infrastructure to improve water management. In so doing, it has often brushed aside traditional and Indigenous knowledge that embraces greener approaches,” Gilbert Houngbo, the chair of UN Water, wrote in the preface to the report.
Global demand for water is expected to increase by nearly one-third by 2050, according to the UN. Meanwhile, climate change is making wetter regions wetter, leading to more flooding which in turn hobbles water infrastructure, and dry regions are getting drier, imperiling water supplies. Two-thirds of forests and wetlands have been lost or reduced since 1900, according to the UN, and since the 1990s, water pollution has worsened in almost all rivers in Africa, Asia and Latin America; both of these trends mean even less of the precious little freshwater on the planet is available for use.
Already, an estimated 3.6 billion people live in places where access to water isn’t guaranteed for at least one month every year, according to the UN. By 2050, that number could grow to as much as 5.7 billion.
“Nature-based solutions” include things like protecting and installing wetlands to soak up flood waters, rehabilitating degraded soils so they can retain more water, recharging groundwater aquifers, and the widespread adoption of farming practices that manage soil so it retains as much rain water as possible.
Many of these methods align closely with the ways indigenous people have historically managed watersheds, but which have also been ignored in favor of industrial-scale interventions, like dams. The UN report urges countries to recognize the efficacy of indigenous approaches.
Indigenous people currently “care for an estimated 22% of the Earth’s surface, and protect nearly 80% of the remaining biodiversity on the planet, while representing only close to 5% of the world’s population,” according to the report. Biodiversity is vital to nature-based solutions to the water crisis; it “underpins ecosystem processes,” the UN writes. A loss of biodiversity of trees and plants make forests less stable and less resilient to storms and disease, which could ultimately threaten the contribution of forests to distributing the water supply and preventing runoff. The same is true when it comes to agriculture; a loss of biodiversity in the fields leads to depleted soils that can no longer hold water.
But indigenous voices have long been shut out from urban and rural planning, and from basic social services. To truly incorporate their knowledge into solving water challenges, that will have to change. As the UN report notes, “For [nature-based solutions] to adequately benefit from contributions of indigenous and tribal peoples, and other sources of knowledge, it is imperative that their socio-economic and environmental vulnerabilities are addressed, and their rights are respected.”
In the world of water management, “nature-based solutions” currently only account for 1% of investment globally, according to the report. But they’re picking up steam. For example, China is investing billions into turning 12 urban areas into “sponge cities” by 2020, which would be equipped with permeable pavement, green roofs, and restored wetlands. The goal is to conserve excess rainwater, which typically floods streets and overwhelms water treatment facilities with contaminated runoff. In a “sponge city,” the rain instead would seep through a system of living buffers, which naturally remove pollutants. Beneath these would be a system of basins to capture the water for reuse.
The UN also pointed to the case of the Puebla Tlaxcala Valley in Mexico, which used to have an unreliable groundwater supply. Volkswagen, which has a factory in the area, worked for six years with the Mexican environmental protection agency to plant trees, dig pits, and build earthen banks. By 2015, the project succeeded in enabling “more than 1.3 million cubic meters per year of additional water for aquifer recharge—more water than the Volkswagen Group in Mexico consumes annually,” according to the UN report.
It isn’t about choosing nature-based or “green” approaches instead of “grey” infrastructure like canals and pipes. That’s a “false dichotomy,” the UN report writes. What we need is the right combination of both for each situation.
Already, all forms of water management blends “green” and “grey” technology; After all, water will always come from a source in nature first. What the UN is proposing is just adding “green” solutions to the mix more often, an approach “that works with natural systems rather than against them.”