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Riparian Margins and Fenced Buffer Strips to Improve Water Quality

Eimear Connery ASSAP Advisor Cork East

Watercourses are an important natural resource. They require ongoing protection from pollution and degradation. From an agricultural perspective, we need to look at ways of reducing the loss of nutrients (phosphorus & nitrogen) and sediment from land and farmyards bearing in mind soil type, topography, rainfall etc. We must aim to identify critical source areas and their flow pathways to identify areas where riparian margins and buffer strips could be located to intercept nutrients from overland flow thereby ‘breaking the pathway’ and putting ‘the right measure in the right place’.

What is a Riparian Margin?
A Riparian Margin is the land that lies adjacent to rivers & streams and other bodies of surface water. The objective of riparian margins is to protect the river by creating linear buffer zones where little or no agricultural activity takes place thereby helping to intercept nutrients transported via overland flow and stabilises the riverbank. These areas also provide suitable habitats for biodiversity and help to take carbon out of the atmosphere providing essential ecosystem services to the general public.

Figure 1: Processes that occur in the Riparian Margin to improve water quality

Riparian margin areas can reduce diffuse pollution by distancing agricultural activity from the riparian area thus reducing the risk of direct pollution from applied fertilisers and by intercepting overland flow to watercourses and acting as a sediment trap to reduce sediment from adjacent fields and nutrient losses to watercourses. They can range in width from 2m to 30m and beyond. If your land is lies within an Area for Action, and you select to fence off an area as a riparian margin to improve water quality this can be claimed as an ASSAP feature in your BPS application and the area will remain eligible for entitlements. 

Riparian Margin Design & Management
Research into the specific management and robust targeting of riparian buffer zones is being conducted by Teagasc, the EPA & the James Hutton Institute through the SMARTER BUFFER Project. This project looks to ensure optimal targeting and management of riparian buffers for the effective management of Irish rivers. The approach used in this research is to locate the riparian buffer/margin in the right place and to optimise the right buffer for pollution pathways and wider multiple benefits.

Figure 2: Image showing flow pathways and potential siting of mitigation measures

Ideally, each river catchment can be characterised and pollution pathways, flow paths and delivery points identified. Then targeted application of riparian margins can be implemented to have a significant impact on improving water quality.  A lot of work in this area is also being undertaken as part of the EPA funded Diffuse Tools Project by UCD and Teagasc among others.  The project aims to develop diffuse pollution models to improve our understanding of how to manage catchments and enhance the evaluation of water quality that are most applicable to Irish conditions and management challenges. This will help to inform catchment managers about potential sources of pollution within a catchment, including identifying critical source areas relating in particular to sediment, phosphorus, and pesticides.