Abstract
Nature-based solutions (NBS) are solutions that can protect, sustainably manage, and restore natural or modified ecosystems in urban and rural areas, while providing many benefits and co-benefits including stormwater mitigation, biodiversity enhancement, and human well-being. As such, NBS have the potential to alleviate many of the environmental, social, and economic issues that we face today. Grey infrastructure, such as lined trenches and catch basins, pipes, and concrete dikes are frequently used for stormwater management and flood protection, but they do not provide many of the co-benefits that are common with NBS. Grey infrastructure is designed to quickly collect and remove rainwater, whereas NBS keep rainwater where it falls, and where it can be used by the environment. Many stakeholders lack knowledge of the capabilities and benefits of NBS, and as a result, they continue to rely on grey infrastructure in their projects. When information is made available on the benefits and how they can be quantitatively measured, it is hoped that NBS will be promoted to a mainstream infrastructure choice. A valuable way to quantify and highlight the benefits of NBS is by using an evaluation framework. There are several evaluation frameworks that qualitatively assess the potential benefits of possible NBS, however there is a need for quantitative frameworks that can assess the actual benefits (or performance) of implemented (or existing) NBS. This article presents an evaluation framework that aims to quantify the benefits and co-benefits of implemented NBS. The framework involves five main steps: (1) selection of NBS benefit categories, (2) selection of NBS indicators, (3) calculation of indicator values, (4) calculation of NBS grade, and (5) recommendations. The outcome of the framework is a single numerical grade that reflects the benefit functioning for an NBS site and values for each performance indicator. This information may be used by decision makers to determine their budget allocations to expand or construct a new NBS site, to update maintenance plans that will improve the benefits of that site, to set up programs to monitor the NBS benefits and co-benefits over time, and to schedule labour and resources for other NBS projects. The framework was tested and validated on a case study of NBS in Thailand. Through conversations with stakeholders and knowledge of the case study area, relevant categories and indicators were chosen. Using data and information obtained through various means, values for each indicator and the overall NBS grade were calculated. The values revealed which benefits were pronounced, those that were weak, and where improvements were required.
Highlights
Extreme weather events affected 60 million people worldwide in 2018; floods were responsible for 35.4 million deaths, storms traumatized 12.8 million people, wildfires caused billions of dollars in damage and were responsible for many deaths, landslides had detrimental impacts on 54,908 people, and droughts affected 9.3 million people [1]
There are many examples of Nature-based solutions (NBS) around the world that have proven their potential in providing benefits to water management, nature, and people
There are several frameworks that are proposed to date, but none of them can be used to assess the full potential of implemented NBS
Summary
Extreme weather events affected 60 million people worldwide in 2018; floods were responsible for 35.4 million deaths, storms traumatized 12.8 million people, wildfires caused billions of dollars in damage and were responsible for many deaths, landslides had detrimental impacts on 54,908 people, and droughts affected 9.3 million people [1]. NBS can be used in combination with grey infrastructure, which are often referred to as hybrid measures [4,5] Such measures can provide a wealth of benefits for people, the environment, and the economy. The benefits and co-benefits of implemented NBS can be observed in different domains and contexts, but systematic evaluation frameworks that can assess their full potential (as well as their possible side effects) are still lacking [15]. Others focus on hydro-meteorological benefits [16]; there are a few frameworks that address the evaluation of implemented NBS, but these provide only qualitative assessments [17]. The framework can be applied 3toofu25rban and rural, large and small scale, hybrid, and catchment scale NBS, and it proposes a combination of severaMl amneythstoadksehtoldasesressasreboutnhceqrutaailnitabtiovuetathnedpqeurafonrtmitatnicveeabnednerefiltiasbwilihtyileofinNteBgSr[a1t8in],gthsetapkreehsoenldt er’s ppraepfeerrefinlclses.ome of these gaps in the NBS knowledge base.
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