Integrating ‘Green’ and ‘Grey’ solutions to protect and secure water resources

The View overhand the river on green forest plain.

An estimated 40,000 people are expected to gather in Brasilia, the Brazilian capital, this week to attend the World Water Forum, a global gathering of water professionals. One of the key issues for discussion is how can we continue to share and sustain water supplies especially with the growing pressures of urbanization, population growth, climate change and land degradation – challenges being faced by countries and communities across the world.

Unprecedented demographic shifts in recent decades mean that for the first time in human history more than half of the total global population now lives in urban areas, up from 34% in 1960. This trend will only continue to grow. In countries, such as China, urbanisation has reached 60% this year. As the demand for food and energy puts additional pressure on land and water resources, the growth of urban areas on the Earth’s land surface is having considerable impacts, not only within cities but also beyond.

Part of the solution is being emphasized through the 2018 theme for World Water Day ‘Nature for Water, exploring nature-based solutions to the water challenges we face in the 21st century. Using nature-based solutions can help meet the water needs of a growing population, while helping to protect the natural environment and reducing pollution.

Cities need to have water management plans in place to navigate increasingly frequent risks such as water scarcity, pollution or flooding. Otherwise the devastating situation currently being experienced by Cape Town, which is on the verge of running out of water, may become the new normal for cities.

Green versus Grey, or Green and Grey?

Traditionally, planning for water security has relied on “grey infrastructure”, such as reservoirs, aqueducts and treatment plants. But research and experience has demonstrated that integrating natural infrastructure – the healthy forests, wetlands and river ecosystems from which water supplies are sourced – can provide sustainable, cost-effective solutions. TNC has shown that by restoring forests and improving land management practices, water quality can be improved, and water treatment costs reduced for four out of five of more than 4,000 downstream cities that were studied.

Investing in nature within and beyond cities can be a cost effective part of securing water supply, to reduce sediment and nutrient pollution, as well as managing flooding risks. For example, source watersheds collect, store and filter water, which can provide sufficient flow and water quality for sustaining water to cities downstream. Approximately a third of the world’s one hundred largest cities rely on protected forest areas to supply a substantial amount of their drinking water.

Action can also be taken within cities to integrate nature into their infrastructure. Greening buildings, permeable paving, urban parks and safe flooding spaces for waterways can reconnect people to rainwater as an opportunity rather than a nuisance. Natural systems such as wetlands and lagoons can play a cost-effective role in treating our wastewater before returning it to our rivers, streams, lakes and aquifers.

Solutions to protect and secure water resources

Water and wastewater utilities are looking for solutions to protect and secure water resources within cities and their surrounding environments. This can be through restoration of watersheds, reforestation, reducing erosion from arable land, groundwater recharge or protecting riverine riparian zones, which can all contribute to improved water quality and flows. To deliver on this requires new thinking, new partnerships, and for individuals and organisations to champion nature-based solutions.

The IWA and TNC have developed a partnership that aims to promote and prioritise natured-based solutions in water and sanitation infrastructure planning and spending. This will leverage IWA’s unrivalled access to urban and utility sectors, and the expertise within its membership to develop and practically apply nature-based solutions, for TNC to generate interest and demand in incorporating nature as a solution.

Nature based solutions are an essential component of solving our world’s growing water problems, and can be applied across scales in basins, cities and water and sanitation services. Connecting water utilities and cities with their basins by exploring how they can actively play a role in watershed management, is a critical step towards success.



Science for Nature and People Partnership

Members of IWA are part of a working group on Sanitation for and by Nature which is being supported by the Science for Nature and People Partnership. The working group is looking at how nature based solutions such as wetlands can be part of wastewater treatment in a way that benefits both human and ecosystem health. The working group is developing evidence based guidance which assesses both the technical feasibility and practicality of placing effective nature-based sanitation solutions such as wetlands in diverse local and cultural contexts.


What can you do for World Water Day?

  1. Find out more what IWA partners and members are doing to apply NBS through the IWA Nature Based Solutions Webinar Series.
  1. Join workshops on nature based solutions engineering and financing at the IWA World Water Congress, 16-21st September, 2018 in Tokyo, Japan

Katharine Cross

Strategy and Partnerships Lead, Australian Water Partnership
Katharine has extensive experience in the water sector from global to local scale with a focus on climate resilience and adaptation, nature-based solutions, water-energy-food nexus,  water governance and the digitalisation of the water sector. She h... Read full biography