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Biodiversity Net Gain – An Opportunity for River Restoration through Development. Dr Sarah Scott National Biodiversity Advisor Agriculture, Fisheries and Natural Environment Environment Agency


What is Biodiversity Net Gain? Biodiversity Net Gain is development that leaves biodiversity in a better state than before.

Net Gain and NPPF 2018 (updated 2019) 118 - Planning policies and decisions should: a) encourage multiple benefits from both urban and rural land, including through mixed use schemes and taking opportunities to achieve net environmental gains – such as developments that would enable new habitat creation or improve public access to the countryside… 170 - Planning policies and decisions should contribute to and enhance the natural and local environment by:….. d) minimising impacts on and providing net gains for biodiversity, including by establishing coherent ecological networks that are more resilient to current and future pressures

171 - Plans should:…. take a strategic approach to maintaining and enhancing networks of habitats and green infrastructure; and plan for the enhancement of natural capital at a catchment or landscape scale across local authority boundaries. 174 - To protect and enhance biodiversity and geodiversity, plans should:

b) promote the conservation, restoration and enhancement of priority habitats, ecological networks and the protection and recovery of priority species; and identify and pursue opportunities for securing measurable net gains for biodiversity.

CIEEM, CIRIA, IEMA Biodiversity Net Gain – Good Practice Principles & Guidance • Principle 1. Apply the Mitigation Hierarchy • Principle 2. Avoid losing biodiversity that cannot be offset by gains elsewhere • Principle 3. Be inclusive and equitable • Principle 4. Address risks • Principle 5. Make a measurable Net Gain contribution • Principle 6. Achieve the best outcomes for biodiversity

• Principle 7. Be additional • Principle 8. Create a Net Gain legacy

• Principle 9. Optimise sustainability • Principle 10. Be transparent

What is a Biodiversity Metric?

The Importance of a Metric Metric is a fundamental part. The metric drives: • Baseline + forecast outcome confidence • Consistency of approach Needs to be: • Simple yet sound July 2019 Biodiversity Metric 2.0 was published by Natural England (beta version). • • • • •

Calculation tool Area Metric (update) Hedgerows (new) Rivers and Streams (new) Intertidal (to come)

Biodiversity Metric 2.0 – Rivers and Streams


Elements considered within the approach 1.

Habitat Distinctiveness – a collective measure of biodiversity that

accounts for parameters such as species richness, diversity, rarity and habitats ability to support species rarely found in other habitats

. Habitat Condition – the condition of a habitat is based on its structure,


species diversity and species abundance. In an area heavily influenced by human activity land management (or lack of) can often drive habitat condition 3.

Spatial risk – these reflect ecological risks derived from the change in

location of a habitat or resource. 4.

Temporal risk – the loss of biodiversity and the delivery of an offset can

be mismatched (i.e. created habitats may take a number of years to become established and reach target condition). 5.

Delivery risk – there are practical risks associated with any proposed

habitat creation or restoration project.


Example Calculation Revised Metric PRE-intervention biodiversity calculation Size of habitat parcel






Strategic location




Biodiversity units

Revised Metric Post -intervention biodiversity calculation

Size of habitat parcel



Habitat parcel Measure of biodiversity quality




Strategic location



Risk Factor Value in biodiversity units




Time to target condition


Spatial Risk


Biodiversity units

Riverine Distinctiveness Priority River Habitat and River Naturalness Assessment. Priority River Habitat based on WFD criteria. River Naturalness Assessment based on citizen science approach. Three scores – Moderate, High, Very High. Led by Natural England. 1. Assess Priority Habitat classification using available data sets (http://publications.naturalengland.o ). 12

2. Assess naturalness classes using available web based mapping (

3. Conduct survey if naturalness class and/or Priority River Class unknown ( -content/uploads/River-naturalnessassessment-guidance-documentFebruary-2019.pdf .)

Riverine condition Needs to consider River type (13 river types). Needs to assess: riparian, channel, bank face and marginal habitat. Needs to capture processes. River Metric Survey (based on citizen science approach) https://modularriversurve 13

River Metric Survey Citizen Science approach - fits simplicity principal ‘what you see, not what you know’ (Based on Modular River Survey – MoRPh) Surveys 15 channel features including: channel, channel margin, riparian, marginal toe. Physical character recorded. Morph units are defined by river size.


Layout of a MoRPh survey, Modular River Survey, 2018.

River Metric Suvey Reach

Sub reach

• Looks at the Reach scale. • Classifies River Type. • Desk based exercise.

• Assesses river processes at the SubReach • Consists of 5 MoRPh units • Defines the hydrogeomorphological character.


Condition Classification • Based on quality parameters expected for river type and degree of human modification.

Case Study- Improving condition Tokynton Park, River Brent, River Restoration Project.


Habitat description

Condition Score


Canalised section of river with no/limited in channel habitat diversity, hard revetment and low habitat diversity riparian zone.

Fairly Poor (2)


Re meandered channel reinstating varied flow types and in channel features, such as riffles and pools. Hard revetment removed and banks re - profiled.

Fairly Good (4)* *the presence of invasive species and some sections of hard revetment limit this section achieving Good (5).

Riparian Zone Difficult to account for within the calculator not a defined habitat type measured in different units to linear features double counting

Assess riparian habitat quality within the condition assessment. Calculate any impact/reduction of riparian habitat within river ‘units lost’. Reason – loss in functionality of the river corridor. To ensure no net loss / net gain, riparian improvements and in-channel enhancements can be considered. 17

Quality Elements and Risk Multipliers Strategic significance: reflects work in priority areas and accounts for distance of offsets. Description of multiplier

Strategic multiplier 1 1.15

Low potential/ action not identified in any plan. Delivery of River restoration actions within: • Local Plans • River Basin Management Plan • Catchment Plans • Catchment Planning System

Spatial multiplier: accounts for distance of offsets Description of multiplier Spatial multiplier 0.75 0.5

Outside Waterbody Outside Catchment

Time to target condition: enhancement and creation 18

Biodiversity Metric 2.0


Changing condition Site Baseline

Site Enhancement


Headline results


What would an offset be? Actions within the River Basin Plan/Catchment Planning System/Catchment Plans can be used as offsets. To be agreed with Local Authority and Environment Agency?

Mitigation for WFD compliance can be used to account for ‘No Net Loss’ but not ‘Net Gain’ (needs to be additional to count as Net Gain, and not part of a statutory requirement). Future proofing? Need to consider what was planned for the river if the development hadn’t occurred. 22

Why will this make development easier? Transparency, efficiency, understanding.

Hang on, what about our duties under the Environment Act and NERC?

We have a commitment to create Priority Habitat 23

This is a nice to do. No, a bat box won’t do – we’ve lost 3 hectares of lowland meadow. We’ve already compensated ?

It’s too much money

It’s not proportionate to the impact

Key messages The Biodiversity Metric, 2.0 will make the requirement to enhance more transparent. Opportunities for river restoration and deliver objectives under Water Framework Directive and Catchment Plans. Part of Nature Recovery Network. For further information: 24

Profile for Suffolk Naturalists' Society

Biodiversity Net Gain River Metric Sarah Scott  

Biodiversity Net Gain River Metric Sarah Scott  

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