Professor Chris J Spray MBE, FCIEEM, FRSA – Written evidence (NSD0004)



I am a recently retired (now emeritus) Professor of Water Science and Policy at the UNESCO Centre for Water Law, Policy & Science at the University of Dundee, Scotland. My research interests focus on freshwater ecosystems, their governance, integrated water resource management and river restoration, including the use of nature-based solutions to reduce flood risk and combat climate change.


My reasons for submitting evidence to the House of Lords Science and Technology Select Committee reflect my research interests and practical experience and, in particular my role as the Scientific Project Manager for the Eddleston Water project, Scottish Government’s long-running study on Natural Flood Management (NFM) and Habitat Restoration in the Tweed valley. I was also the lead author of the Chapter on Freshwater Systems in the report by the British Ecological Society in 2021 on Nature-based Solutions for Climate Change in the UK, ( And thirdly, as a Trustee and past Chairman of the internationally recognised participatory catchment NGO, Tweed Forum (, I have extensive experience of working with farmers and other land managers to deliver nature-based solutions on the ground, including piloting the Scottish Land Use Strategy using an Ecosystems Approach.


I only wish to submit evidence on a restricted number of topics and with reference mainly to freshwater ecosystems and catchment land use in the UK. In doing so, I cover some topics that might fall more easily in to the category of adaptation rather than mitigation, but I feel that there are still key learning points to be made in these instances.



1. What is the potential scale of the contribution that nature-based solutions can make to decarbonisation in the UK? and

2. What major scientific uncertainties persist in understanding the effects of nature-based solutions and affect their inclusion in carbon accounting, and how can these uncertainties be addressed?


Evidence that we gathered for the 2021 BES Report on Nature-based Solutions for Climate Change in the UK shows that freshwater habitats play a critical role in the carbon cycle through high rates of respiration and sequestration. However, this is a complex area as whilst rivers, lakes and ponds can be significant sinks, they can also be important sources of carbon, and there are many uncertainties as to the exact conditions under which they can and do deliver positive mitigation outcomes. Further research is required to determine how the mitigation potential can be optimised through the use of nature-based solutions.


One area which seems promising in a UK context is ponds which, with the correct management have been demonstrated to be effective carbon sinks. As we note in the BES Report, carbon burial rates in typical lowland ponds (over 18-20 years) may be in the region of 5 tonnes of carbon dioxide per hectare per year (range 3-9) once the pond is over 2-3 years old and vegetated. However, uncertainties persist as to how long such rates may be sustained, particularly with shallow ponds subject to a range of pressures, but more mature ponds with higher rates of vegetation are more effective at sequestering carbon. Given that they are widespread and occur in all habitats, including urban environments, they could be seen as an investment priority, not least as pond creation and management can easily be implemented by small groups and individuals across a wide scale.


3. What frameworks already exist for the regulation and financing of nature-based solutions?

Evidence from our work across the Scottish Borders, and in focussed projects such as the Eddleston Water Natural Flood Management (NFM) study ( demonstrates that within existing regulations, the financing of nature-based solutions relies on local initiatives and, in particular the work of a ‘Trusted Intermediary’ (Tweed Forum) being able to develop hybrid funding mechanisms.


Since 2010, this long-term empirically-based project has worked closely with farmers and communities across the 69km2 catchment of the Eddleston Water to deliver a range of nature-based solutions to reduce flood risk, including re-meandering 3km of river channel, planting over 330,000 native trees, installing 136 low-flow woody dams and the creation of 37 flood storage ponds, at a combined cost (excluding major in-kind resources from partners and landowners) of some £2.6 million (scoping, set up and baseline monitoring - £355k; design & capital works - £1.3m; monitoring, evaluation & modelling - £925k). Funding has come from a variety of public, private and other sources, including Scottish Government, Scottish Environment Protection Agency, Scottish Borders Council, Scottish Forestry, Scottish Natural Heritage, Tweed Forum, Forest Carbon, CEMEX, Woodland Trust, British Geological Survey and University of Dundee.


I would highlight the following aspects as requirements to apply a similar approach elsewhere:

              An underpinning legal framework such as the Flood Risk (Scotland) Act 2009 that requires consideration of Natural Flood Management as nature-based solutions (Section 20) alongside other infrastructure options for any and all flood schemes promoted in Scotland;

              A funding mechanism that enables landowners to maintain the long-term profitability of their farm businesses alongside the introduction of NFM measures across the catchment landscape. This may involve public payment for the delivery of a range of public goods and wider benefits (flood risk reduction, carbon management, habitat improvement, water quality protection, etc.) as part of agri-environment schemes, as well as agricultural production;

              The development of a hybrid funding package utilising government, commercial, charitable and other sources, that can be utilised both at the catchment scale and in discussion with individual land managers;

              A mechanism for true engagement with the landowners, via a trusted intermediary such as the Tweed Forum; and

              The assessment and valuation of the multiple benefits that nature-based solutions provide - Appraisal of NFM measures already implemented in the Eddleston show a positive net present value (NPV) of £950k from flood damages avoided, and a potential £2.85million NPV from flood damages avoided for an enhanced NFM scenario that delivers greater flood risk reduction. Crucially however, the net present value of other co-benefits delivered by the same NFM measures is much higher. Existing benefits from water quality improvements, carbon management, recreation, biodiversity and fisheries amount to £4.2million NPV on top of the £950k from flood damages avoided, and £17.7million NPV for the scenario proposed.


4. Who are the key stakeholders for the implementation of nature-based solutions in the UK? How can stakeholders’ expertise and concerns inform the incentives and requirements for implementing nature-based solutions?

Trusted Intermediary - Our work on the Eddleston Water and more widely across Tweed these past 30 years shows that having a ‘Trusted Intermediary’ that sits and works between the national (top-down) policy agendas of government and regulators on the one hand and, on the other the (bottom-up) individual and community desires and business challenges at a local level is key. Working in this ‘space’ Tweed Forum are able to understand and translate policy and practice to the different stakeholder audiences, as well as seeing the potential for multiple benefits and matching potential multiple finance sources.


Stakeholder strategy - Using a stakeholder strategy developed for promotion of natural flood management initiatives, we recognise diverse stakeholders. For each, an assessment can be made as to a) their potential interest in nature-based solutions and b) their influence on the potential implementation of such nature-based solutions. From this comes the identification of key stakeholders, and an assessment for each as to the key messages and the key means of communication that will be necessary for two-way dialogue.


Key elements required to support farmers include:

              Close engagement with the landowners is central to successful implementation of nature-based solutions. On Tweed, this works well because it is carried out by Tweed Forum, who are trusted by the farmers as a neutral non-government party. They understand the farmers’ business, and the type of areas and options that can work both as nature-based solutions (e.g. to reduce flood risk) and for the farmers (at least economically neutral). Tweed Forum has learned that it is essential to use the right language and find the right trade-offs: not necessarily the ideal solutions from a climate change flood risk perspective, but solutions that are manageable within individual farm business plans, balancing effectiveness with the impact on farming. This includes obvious considerations of land productivity and access, but also impact on subsidies.

              Simplicity of ‘paperwork’ – in promoting and implementing nature-based solutions, Tweed Forum routinely undertake all necessary ‘paperwork’ for application for grants, planning, contractors, etc. Without this, many farmers would not get involved, so simple, rapid administration and prompt (re)payments (even up-front) are essential.

              Long-term financing arrangements – interviews with farmers reveal that an essential pre-requisite is to have long-term financial support, not five year ‘packages’ if nature-based solutions are to be seen as attractive.

              Long-term control of their land - whatever nature-based solutions are promoted, it appears very important to farmers to retain some form of long-term control of their land, so as to retain future land management options.

              Examples – we find that it helps convince farmers if they can see that a solution is working well in other places and for other farmers. Clever modelling and excel spreadsheets alone are not going to convince them.

              Public Engagement: meaningful bottom-up engagement with relevant stakeholders may require re-thinking current methods of public consultation and stakeholder engagement at regional and local level – not ‘business as usual’ consultation processes

              Community stakeholder engagement - The project has made considerable effort to engage with the downstream communities and the wider public, through stakeholder meetings, organising project visits, conferences and wider publicity.


5. How should implementation of nature-based solutions be integrated with other government policies for landscapes and seascapes, for example, agricultural, forestry, and land-use planning policies?

Our experience of working in the Scottish Borders shows that the four key aspects to be considered in promoting and delivering nature-based solutions are:

1.              A legal framework such as the Flood Risk (Scotland) Act that demands consideration of nature-based solutions – felt to be fundamental to successful delivery. As well as providing a clear focus and direction (see for example the Welsh approach to Sustainable Management

of Natural Resources, backed by the three Acts - The Well-being of Future Generations (Wales) Act, the Environment (Wales) Act and the Planning (Wales) Act), policies of government, their agencies and local government need to align. This needs to direct the actions of all land management (and water) based Agencies.


2.              Partnerships and new ways of working - need to adapt existing forms of statutory and partnership working to recognise and value different Statutory, Community and Land management perspectives when taking a nature-based approach. As noted, using a ‘Trusted Intermediary’ can help get the key messages out and provide access to networks and enhance buy-in from external stakeholders. Other governance options need to meet this challenge, but adding new layers of administration is not welcomed and should be avoided.


3.              A mechanism that enables the landowners to still operate financially but delivers nature-based solutions individually and at a landscape scale, by finding a trade-off between wider benefits (flood risk reduction, habitats) and farming economics. This may mean that instead of small agri-environment scheme ‘offers’ we need to think more about whole landscapes and how to ‘join up’ nature-based solutions spatially and temporally. Seeing everything as ‘additional voluntary’ menu options within the small theme of agri-environment support to individual farms as opposed to looking at main stream land use and farming will not deliver with the urgency, scale and impact needed. We see that the best scale for adoption of nature-based solutions appears to be the sub-catchment or local community, rather than at regional or multi-regional levels.


4.              A mechanism for true engagement with the landowners and land managers, such as via a trusted intermediary or other locally based informed organisations. This needs to bridge the individual and the group approach.


18 August 2021