Five billion people could be left with poor access to water by 2050 if nothing is done to enhance its supply and quality, a report has revealed.
The stark warning was made in the 2018 edition of the United Nations World Water Development Report.
The study’s publication, which coincides with World Water Day on March 22, argues reservoirs, irrigation canals and water treatment plants are not the only water management instruments at our disposal.
Nature-based solutions (NBS), such as water harvesting structures and regenerating soils and forests, need to be embraced to “avoid water-related conflicts”, the report states.
“If we do nothing, some five billion people will be living in areas with poor access to water by 2050,” said Audrey Azoulay, Director-General of UNESCO, during a joint presentation of the report with Gilbert Houngbo, Chair of UN-Water, at the 8th World Water Forum in Brasilia (Brazil).
Azoulay said:
“We need new solutions in managing water resources so as to meet emerging challenges to water security caused by population growth and climate change.
“This report proposes solutions that are based on nature to manage water better.”
NBS measures have already been practised to stunning success.
In 1986, the Indian State of Rajasthan had experienced one of the worst droughts in its history. Over the following years, an NGO worked alongside local communities to set up water harvesting structures and regenerate soils and forests in the region.
This led to a 30% increase in forest cover, groundwater levels rose by several metres and cropland productivity improved.
These measures, said the latest edition of the report, Nature-based Solutions for Water, are good examples of NBS. It recognizes water not as an isolated element, but as an integral part of a complex natural process that involves evaporation, precipitation and the absorption of water through the soil.
The presence and extent of vegetation cover across grasslands, wetlands and forests influences the water cycle and can be the focus for actions to improve the quantity and quality of available water.
“For too long, the world has turned first to human-built, or “grey”, infrastructure to improve water management,” writes Houngbo in the report’s foreword.
“In so doing, it has often brushed aside traditional and Indigenous knowledge that embraces greener approaches.
“Three years into the 2030 Agenda for Sustainable Development, it is time for us to re-examine nature-based solutions (NBS) to help achieve water management objectives.”
Focusing on ‘environmental engineering’
So-called ‘green’ infrastructure, as opposed to traditional ‘grey’ infrastructure, focuses on preserving the functions of ecosystems, both natural and built, and environmental engineering rather than civil engineering to improve the management of water resources.
This has multiple applications in agriculture, the greatest consumer of water by far. Green infrastructure can reduce pressures on land use while limiting pollution, soil erosion and water requirements by contributing to the development of more effective and economic irrigation systems, for example.
A System of Rice Intensification, originally introduced in Madagascar, helps restore the hydrological and ecological functioning of soils rather than using new crop varieties or chemical products.
It enables savings of 25-50% in water requirements and 80-90% in seeds while raising paddy output by 25-50%, depending on the region in which it is implemented.
It is estimated that agricultural production could be increased by about 20% worldwide if greener water management practices were used.
One study cited by the Report reviewed agricultural development projects in 57 low-income countries and found that using water more efficiently combined with reductions in the use of pesticides and improvements in soil cover, increased average crop yields by 79%.
Green solutions have also shown great potential in urban areas. While vegetated walls and roof gardens are perhaps the most recognizable examples, others include measures to recycle and harvest water, water retention hollows to recharge groundwater and the protection of watersheds that supply urban areas.
New York City has been protecting its three largest watersheds since the late 1990s. Disposing of the largest unfiltered water supply in the USA, the city now saves more than $300 million yearly on water treatment and maintenance costs.
China recently initiated a project entitled “Sponge City” to improve water availability in urban settlements. By 2020, it will build 16 pilot Sponge Cities across the country with the goal to recycle 70% of rainwater through greater soil permeation, retention and storage, water purification and the restoration of adjacent wetlands.
Wetlands only cover about 2.6 % of the planet but play a disproportionately large role in hydrology. They directly impact water quality by filtering toxic substances from pesticides, industrial and mining discharges.
There is evidence that wetlands alone can remove 20-60% of metals in water and trap 80-90% of sediment from runoff.
However, ecosystems have limits and cannot filter out all types of toxic substances discharged into the water.
There are tipping points beyond which the negative impacts of contaminant loading on an ecosystem becomes irreversible, hence the need to recognize thresholds and manage ecosystems.
Wetlands also act as natural barriers that soak up and capture rainwater limiting soil erosion and the impacts of certain natural disasters such as floods.
With climate change, experts predict there will be an increase in the frequency and intensity of natural disasters.
Some countries have started taking precautions. For example, Chile announced measures to protect its coastal wetlands after the 2010 tsunami. The US State of Louisiana created the Coastal Protection and Restoration Authority following Hurricane Katrina (2005), whose devastating impact was magnified by the degradation of wetlands in the Mississippi Delta.
Nevertheless, the use of nature-based solutions remains marginal and almost all investments are still channelled to grey infrastructure projects, the report said.
Yet, to satisfy the ever-growing demand for water, green infrastructure appears to be a promising solution complementing traditional approaches.
The report’s authors call for greater balance between the two, especially given that nature-based solutions are best aligned with the Sustainable Development Goals adopted by the United Nations in 2015.
