Projected climate change over the next century is expected to increase the frequency and severity of floods. This, coupled with the pressure of population growth, is likely to result in increasing pressure on flood risk management in order to maintain current levels of protection.
In recognition of this pressure, there has been increasing interest in more sustainable approaches to flood risk management that can complement our existing defences and increase their resilience and adaptability to climate change.
Manage the sources and pathways of floodwaters
One such approach is natural flood management (or NFM) – a catchment scale technique that involves working with natural features and processes to manage the sources and pathways of floodwaters.
Natural flood management typically involves restoring the natural capacity of a catchment to slow or store floodwater and covers a spectrum of measures from full-scale restoration of the course of a river or inter-tidal habitat to smaller-scale land management measures such as upland drain blocking.
In addition to benefits to flooding, these techniques can also often easily incorporate, and contribute to, improvements in biodiversity, water quality, and carbon storage which, in turn, can improve access to wildlife, recreation, and jobs and ultimately our overall health and wellbeing.
Where the cost of traditional flood defences cannot be justified, such as where the number of properties at risk is very small, natural flood management might also be a cost-effective way for local communities to help address flooding.
Encourage communities and land managers to come together
This will be increasingly relevant as the pressures on funding become greater. Managing flood risk in this way can encourage communities and land managers to come together and seek out solutions that they themselves can deliver.
In Scotland, identifying opportunities for NFM is a statutory requirement set out in the Flood Risk Management (Scotland) Act 2009. In preparing Scotland’s Flood Risk Management Strategies, SEPA in conjunction with other flooding responsible authorities, carried out analysis and identified more than 100 areas where NFM could potentially make a contribution to flood risk reduction. Local authorities are now tasked with assessing these opportunities in greater detail.
NFM delivery is not without its challenges, however. Most evidence suggests NFM is effective for more frequent local flooding, but there is little empirical data on the effects of NFM at the larger catchment scale. Justifying and appraising NFM alongside other FRM actions is therefore often challenging.
Buy-in from multiple individuals and organisations
It is also a new approach for many that therefore requires guidance and support together with collaboration and buy-in from multiple individuals and organisations, including communities at risk. Incentivising landowners to progress NFM can also be difficult, especially if they are being asked to utilise productive land.
In anticipation of some of these challenges, SEPA has been working with Scottish government and other partners on a variety of activities to support delivery of NFM. These include the development of opportunity maps for NFM for Scotland and flood modelling guidance, as well as advice on the compensation mechanisms that might be used to support the land managers that undertake NFM works.
In 2016, SEPA produced a Natural Flood Management Handbook - the first comprehensive manual on NFM covering all aspects of this approach from assessment tools and scoping to funding and monitoring. Scottish government has also revised its agri-environment payments so that they better accommodate NFM delivery by farmers.
However, clearly the evidence base is the area where most progress is required. To this end, Tweed Forum, an experienced and active NGO in the field of NFM, has led on Scotland’s flagship NFM research project located on the Eddleston Water in the English/Scottish cross-border catchment of Tweed.
Funded by multiple private and public partners, including Scottish government and SEPA, about £400,000 has been spent on multiple measures across 12 farms, including river restoration, riparian planting and woody debris dams.
Data from a hydrological and ecological monitoring network
Data from an extensive hydrological and ecological monitoring network in this catchment will be used to assess the flooding and wider benefits of these measures to local communities.
Of course, Eddleston Water is just one of many projects examining the effects of NFM features. Coastal NFM, such as sand dune restoration and beach recharge, has been the subject of considerable research, particularly in the Netherlands and neighbouring countries.
As a result, Rijkswaterstaat, an agency of the Dutch Ministry of Infrastructure and the Environment, leads on an INTERREG Building with Nature project aimed at funding monitoring and collaboration on NFM research internationally, including on the Eddleston Water. The Environment Agency has also contributed to the evidence base by collating the first comprehensive evidence directory on NFM.
Clearly establishing a robust evidence base on NFM will take time and quantifying the benefits to flooding will remain challenging. However, when considered together with the many additional benefits it can provide, NFM can compare favourably against other traditional flood risk management measures and assist in delivering many other statutory targets and requirements.
Author: Heather is a senior policy officer in SEPA’s Flood Risk Management team. She leads on natural flood management and works closely with Scottish Government and other partners to facilitate and identify opportunities for natural flood management in Scotland, including the development of assessment tools, financial instruments, guidance and research as well as the delivery of projects on the ground. She was lead author of SEPA’s Natural Flood Management Handbook.