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Nature-based Catchment Management – working with nature to benefit biodiversity, water and the climate

Nature-based Catchment Management means working with nature and using natural processes where possible to protect and improve water quality in our catchments. New frameworks are being developed to help identify the right measure for the right place, with a focus on multiple benefits for water, climate and biodiversity.

Nature-based Catchment Management (NbCM) measures are multi-functional measures that aim to protect water resources and address water-related challenges by restoring or maintaining ecosystems as well as natural features and characteristics of water bodies using natural means and processes (EU, 2014).

The main functions of these measures are to reduce flood risk, improve water quality, and create habitats. In carrying out these functions these measures can also provide multiple co-benefits such as climate regulation, climate change adaptation, improved soil management, and the creation of amenities. It must be noted that the concept of NbCM is not a new one and many of these measures already exist and are being actively implemented within different sectors plans and policies in Ireland. NbCM are ideally used as part of the overall Integrated Catchment Management (ICM) approach. Many measures are ineffective when deployed in isolation without other supporting measures. The ideal solution will be at the catchment scale usually taking the form of a suite of measures designed to complement each other across the landscape. The key benefit of these measures lies in the multiple benefits that they bring.

Multiple benefits include:

improving water quality
regulating water storage and delivery
flood risk reduction
sequestering carbon
supporting and enhancing biodiversity
improving amenity value (e.g. angling and walking)
health benefits (e.g. mental health benefits/improved air quality)
aesthetic quality (e.g. visually desirable features such as ponds)
cultural benefits (i.e. tourism and recreational value of rivers)
climate change resilience (e.g. increased buffering to extreme rainfall events)

Figure 1: Engineered ditch as part of a study at Newcastle University.

How does this fit in with the Water Framework Directive?

The objective of the WFD is to prevent any further deterioration in status of surface waters, groundwater and water dependent ecosystems, and to restore polluted water bodies to at least good status. The EPA is responsible for assisting with the preparation of the River Basin Management Plan (RBMP), including undertaking initial characterisation which involves an assessment of pressures and impacts of all water bodies in the country.

During the 2nd Cycle Characterisation process, hydromorphological pressures were identified as the second most prevalent significant pressure type for “At Risk” river water bodies. This pressure relates to damage to habitat and natural river, lake or transitional/coastal (TraC) water body processes through physical modifications. Physical modification includes channelisation, land drainage, dams, weirs, barriers and locks, overgrazing, embankments and culverts.

The EPA leads the national hydromorphology work programme under the aegis of the WFD National Technical Implementation Group. This was supported by a Natural Water Retention Measures (NWRM) Working Group. The NWRM group was co-chaired by EPA and OPW and was tasked with assessing the potential for implementing Natural Water Retention Measures in Ireland, as part of a suite of measures to address water quality, reduce flooding and achieve other environmental outcomes.

The group produced a report for the WFD National Technical Implementation Group (NTIG) and the output of their work will feed into the development of the Programme of Measures for the 3rd Cycle RBMP. It was recommended as part of this work to refer to these measures as Nature-based Catchment Management (NbCM) as a significant proportion of the measures identified during the review are not primarily focused at flood prevention or mitigation.

What do these Nature-based Catchment Management measures look like?

There are a significant number of measures which fall under this heading and are capable of achieving multiple benefits. Measures vary in scale, cost and applicability from very small-scale measures such as permeable pavements in urban settings to large scale river restoration projects spanning tens of kilometres of river channel.

An example of a NbCM measure identified as having high potential for implementation in Ireland is engineered ditches. This measure is designed to reduce flow velocities in networks of traditional agricultural or forestry drainage ditches. The principle is to re-engineer existing ditch cross-sectional areas to incorporate flow control structures and, where practical, widen and flatten the ditch to further reduce flow velocities (Environment Agency, 2012). Engineered ditches will have a limited lifespan before maintenance is required as sediment will eventually accumulate upstream of the flow barriers. Many of these methods have been trialled at the Nafferton Farm study led by researchers from Newcastle University and have shown this measure to be very effective at removal of sediment, nutrients and in dampening the peak discharge to watercourses (Quinn et. al., 2007). Given the vast network of drainage ditches present across the country, this measure has the potential to provide enormous benefit if rolled out nationally in a targeted manner. These measures can also have multiple benefits for climate and biodiversity as well as water quality.

How can these measures be implemented nationally?

The EPA are currently overseeing a national project which is developing a draft framework for prioritising measures for both river restoration and NbCM. This will allow targeting to suit the position with the catchment and the specific setting in which measures are to be implemented. This work is steered by NWRM working group members in consultation with key stakeholders. It is anticipated that this project will be completed by the end of 2021.

The availability of a national implementation framework and associated decision support tools will allow policy makers, state agencies and local community groups to target the right Nature-based Catchment Management measures in the right place and help achieve maximum multiple benefits from targeted investments.

Patrick Morrisey, EPA Catchments Unit

Learn more:

Terms of reference for the Natural Water Retention Measures Working Group and a report prepared by that group on Nature-based Catchment Management can be downloaded here: https://stg.catchments.ie/download/wfd-natural-water-retention-measures/

About author

EPA Catchments Unit

Administrator

The EPA Catchments Unit is based in Dublin, and the team is involved with catchment science, chemistry, ecology, hydromorphology, modelling, Geographic Information Systems and planning. We work with the wider EPA, all of our local authorities, the Local Authority Waters and Communities Office, the Department of Housing, Planning and Local Government, and other public bodies and Departments to ensure we have the best available data and information about our catchments.

Who is involved?
Quite simply, everyone in Ireland has a role to play. This can be from something as simple as making sure you don’t pollute your local stream, or a local community working together to establish a Rivers Trust to enhance the rivers and lakes in their area, to a Government Department or Agency helping a Minister implement a new policy to help protect and enhance all our water bodies.

This website has been developed and is maintained by the Environmental Protection Agency, and is a collaboration between the Department of Housing, Planning and Local Government, the Environmental Protection Agency, and the Local Authority Waters Programme.

Local Authority Waters Programme

The Local Authority Waters Programme coordinates the efforts of local authorities and other public bodies in the implementation of the River Basin Management Plan, and supports local community and stakeholder involvement in managing our natural waters, for everyone’s benefit.

Environmental Protection Agency

The EPA is responsible for coordinating the monitoring, assessment and reporting on the status of our 4,842 water bodies, looking at trends and changes, determining which waterbodies are at risk and what could be causing this, and drafting environmental objectives for each.

Department of Housing, Local Government and Heritage

The Department is responsible for making sure that the right policies, regulations and resources are in place to implement the Water Framework Directive, and developing a River Basin Management Plan and Programme of Measures to protect and restore our waters.