In the last two decades, the impacts of natural disasters have been devastating, affecting over 4 billion people, including killing more than 1 million, and causing around $2.9 trillion in economic losses. Watershed degradation has impacted drinking water for over 700 million people, costing global cities alone $5.4 billion in treatment and droughts affect an average of 35 million people each year.
Traditionally, "grey" or "hard" infrastructural solutions — engineering projects that use concrete and steel — have dominated efforts to reduce and manage impacts from natural disasters and to manage water resources. However, internationally the focus is shifting towards nature-based solutions for water resource management, disaster risk reduction, and climate change adaptation.
Natural systems have long provided many of the services communities seek from grey infrastructure — protection from natural hazards and provision of key resources such as water and energy. Natural systems also provide additional benefits. For example, mangroves provide coastal protection, but can also support fisheries and food security, timber, non-timber forest products, tourism, and act as a significant carbon sink.
Nature-based solutions (NBS), or "nature-based infrastructure" is an approach that uses natural systems to provide critical services, such as wetlands for flood mitigation or mangroves to reduce the impact of waves, storm surge, and coastal erosion. These solutions can also synergize with grey infrastructure, forming so-called "hybrid" solution.
NBS can provide a cost-effective and flexible approach for disaster risk and water resource management.