3 key ways ecologists or River Condition Assessment surveyors can contribute to biodiversity net gain

Many ecologists have skill sets developers need to meet BNG application planning requirements, but fewer have credentials relevant to one key area: River Condition Assessment (RCA).

Separate RCA credentials are required to qualify as a competent assessor of most watercourses on or near the developer’s property. Ecologists who do not have these credentials can earn them by completing the Modular River Physical Survey (MoRPh) technique training to assess watercourse physical structure and habitats. Another alternative is for the ecologist or developer to engage with an individual who does hold the RCA credentials.

If you are an ecologist or an RCA consultant who is familiar with using tools like Cartographer for river assessments, it’s also essential that you understand how River Condition Assessments work with BNG.

On the surface, Defra’s Statutory Biodiversity Metric includes assessment criteria for most land-based habitats. It also describes the questions that must be answered with data gained in river assessments, which include both desk-based and field-based undertakings.

Read on to gain an understanding of 3 key ways RCA assessors can deliver river assessments and provide crucial contributions to BNG planning.

Address encroachment in the river and riparian zone

You will need to calculate encroachment in order to determine the BNG value of a watercourse. While aspects of encroachment are measured during the RCA assessment, an additional assessment of the percentage cover of encroaching features and their distance to the watercourse must be conducted.

Encroachment includes any human-made structures or human activities within the river and the riparian zone that hinder wildlife access or degrade habitat quality.

To evaluate watercourse encroachment:

• Identify encroachment within the watercourse where river functioning is impacted by manmade objects, such as weirs, dam, jetty, or a concrete bank on the side of the river.
• Assess the percentage of watercourse impacted by encroaching features.
• Classify encroachment levels (minor, moderate, major) based on the coverage percentage.

For riparian zone encroachment, it is essential to:

• Identify encroaching features within the riparian zone (that is, 10 metres beyond the top of the riverbank or 5m beyond a ditch bank).
• Assess any structures or interventions within the riparian zone that affect habitat quality.
• Use the BNG metric to classify encroachment severity.
• Document and photograph encroachment features for accurate reporting.

Encroachment evaluation should be part of your RCA to provide a comprehensive assessment of the river’s health. Understanding and mitigating these impacts will improve both the river condition and overall biodiversity.

Plan Corrective Measures

As a credentialed RCA consultant, you can suggest corrective measures to mitigate encroachment and enhance river condition. Examples include:

• Removing non-natural structures or barriers.
• Restoring natural vegetation along the riverbanks.
• Improving water quality by managing agricultural runoff or urban discharge.

Your expertise can guide landowners in implementing these measures, contributing to better river health and increased biodiversity.

Integrate RCA and BNG for Holistic Assessments

Combining RCA and BNG assessments provides a holistic view of river health. While RCA focuses on the physical and ecological condition of rivers, BNG emphasizes enhancing biodiversity. Together, they provide a comprehensive framework for river management. Ecologists can:

• Conduct RCA to establish the baseline condition.
• Combine field survey with a desk-based survey that classifies the characteristics of the river.
• Evaluate encroachment according to the Statutory BNG Metric and suggest mitigation strategies.
• Apply BNG metrics to measure biodiversity improvements in the riparian zone over time.

This integrated approach ensures that all aspects of river health are addressed, leading to sustainable and resilient river ecosystems.

Create the full BNG application to champion biodiversity

Certified RCA consultants, whether ecologists or independent RCA surveyors, play a vital role in promoting biodiversity through careful assessment and management of river conditions. By understanding and applying BNG principles, addressing encroachment, and suggesting corrective measures, you can significantly enhance the positive impact on biodiversity and natural habitats.

Click here for more information on AiDash BNGAI and its ability to include BNG benchmarking and planning as well as River Condition Assessments in BNG planning applications.

Justin Byrne, PhD MCIEEM 
AiDash Senior Ecologist – EMEA, R&D

Justin is an RCA trained ecologist, with particular expertise in BNG, remote sensing, and woodland ecology. Justin’s work and research has primarily focused on how we use modern technology to revolutionize how we do ecology; including the use of eDNA, satellites, and drones to study biodiversity and ecosystems in partnerships with The Woodland Trust, Forest Research, The Wildlife Conservation Society, Grown In Britain, and other organizations.