Why we need clarity and ambition for Nature-Based Solutions

May 24, 2024

In March 2024, Natural England released guidance on different nature-based solutions (NbS) for nutrient mitigation. Having just completed the draft of a supplement to this guidance on a novel approach to drainage ditch management, I have now had time to really get my head around the existing NbS evidence-based and deployment framework reports. This might sound like an odd statement, seeing as I am listed as an author on these documents, but I was only involved in the early stages of the project prior to leaving Ricardo.

It's great to see a wider range of nature-based solutions being recognised as having a potential role in delivering nutrient mitigation. Since I founded Greenshank, we have focussed in on the mitigation methods that have the most potential for nutrient mitigation to support nutrient neutrality and are now months aways from deploying novel nutrient mitigation solutions. Some of my key reflections on the guidance, based on my experience of the challenges of working towards deploying these solutions, are:

1. Parsimony, Occam’s razor – hang on a sec, I’m overcomplicating this! Simple is best. Guidance should be written so that project proposals that follow the guidance provide the required confidence without unnecessary detail.

2. Very few NbS have an evidence-base with 10s to 100s of studies that can be used to easily arrive at that mythical kg/year of nutrients reduced number. However, certain solutions do have an evidence-base that allows for that mythical number to be estimated with confidence using a cogent argument stemming from first principles. These principles can be backed up by at least a few 10s of studies that may not all report results in precisely the *right way*.

3. While progress is being made to meet nutrient mitigation demand across the affected catchments, it is still hampered by reliance on wetlands and land use change schemes. We need cheaper and faster approaches to meet mitigation demand in a manner that does not cause viability problems for developers. Riparian buffers are only going to deliver a small amount of mitigation quickly, so we need other solutions.  

Over the past year, I have been in the weeds, pushing forward our ideas and thinking on low-tech innovation using NbS. Our thinking has developed beyond the recent published guidance, and it is being incorporated into the upcoming framework on drainage ditch management schemes for nutrient neutrality.

We are also pressing on with our approach to beaver dam analogue (BDA) deployments for nutrient mitigation. This combines a rigorous analysis of the evidence on beavers and BDAs as ecosystem engineers, combined with specific design recommendations, to support the use of BDAs for nutrient neutrality.

With these two approaches combined, we have identified opportunities that could deliver:

- Over 9000 kg N/year and 470 kg P/year in the Stodmarsh catchment.

- Over 46,000 kg N/year and 1000 kg P/year in the Broads catchment.

- Over 5900 kg N/year in the Tees catchment.

And this amount of mitigation could be delivered for less than cost of a single large wetland in each catchment.

One of the key criticisms of nutrient neutrality is the additional cost burden it places on developers. This impacts viability assessments and when viability is put at risk, affordable housing tends to be sacrificed for developments to be built and bring forward much needed housing stock. I have spent countless hours assessing mitigation opportunities. This has shown me that with drainage ditch management solutions and BDAs, as well as existing mitigation methods that NE already supports, we can make nutrient neutrality deliverable across all affected catchments. But to make this happen, we need clear and robust guidance for high yielding and quick to deploy mitigation solutions. With this, we can accelerate mitigation deployment, increase mitigation supply, and reduce the costs and delays associated with this new requirement to build sustainably.    

If you are landowner or land agent, or you are friendly with people who own land in an NN catchment, drop me a line as you may be sitting on a great opportunity that we can help you realise.


Dr Gabriel Connor Streich

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