Ditch BNG Units
Medium
Watercourse
Trusted by Developers and Landowners
What are Ditches?
Ditches are linear watercourses, usually artificial in origin, dug for drainage or water management. Many are simple farmland drains, but others have developed rich communities of aquatic plants, invertebrates, amphibians, birds, and mammals. Their biodiversity value depends on water quality, vegetation, and management.
Why It Matters for BNG
Ditches provide linear aquatic units essential for meeting metric requirements in lowland landscapes. Well managed ditches support aquatic plants, amphibians, and invertebrates.
Routine ditch management, water quality protection and vegetation control enable landowners to produce linear BNG units with limited change to current practice.
Where Do They Occur?
• Across lowland agricultural landscapes, especially in arable and grazing systems
• In lowland floodplains, grazing marshes, and fenland
• Along field boundaries, tracks, and roadsides
• As part of historic drainage systems in wet regions
How New Ditches Are Created
Inputs
• Excavate channels to hold water for much of the year
• Profile banks with gradual slopes to allow marginal plants to establish
• Maintain water supply from groundwater or surface inflow
• Avoid lining or over-engineering which prevents colonisation
Management
• Protect banks from livestock poaching with fencing or buffer strips
• Manage vegetation and silt on a rotational basis, leaving some sections undisturbed
• Avoid excessive dredging or clearance which removes all plant life
Landscape
• Position new ditches where they connect into wider ditch networks or semi-natural wetlands
• Maintain uncultivated margins alongside to buffer against fertilisers and pesticides
• Link ditches to hedgerows or grass strips to provide combined habitat corridors
How Existing Ditches Are Improved
Inputs
• Widen or restore buffer strips to reduce nutrient enrichment
• Repair eroded banks and exclude livestock where necessary
• Control invasive non-native plants and animals
Management
• Switch from annual clearance to rotational management to allow vegetation to persist
• Maintain sufficient water levels through the summer to support aquatic species
• Encourage marginal vegetation by leaving uncut stretches each year
Landscape
• Restore connectivity by linking broken sections into longer networks
• Integrate ditches with hedgerows, grassland, or field margins for added ecological value
• Enhance wetland character by diversifying depth and flow
Target Condition
Ditches in Good condition will show:
• Clear water of good quality, with low turbidity and no signs of pollution
• A range of aquatic plants, ideally more than 10 emergent, floating, or submerged species in a 20m length
• Little or no filamentous algae or duckweed (under 10% cover)
• Marginal vegetation along more than 75% of the length
• Less than 5% physical damage to banks and channel
• Sufficient summer water depth (c. 50 cm in minor ditches, 1 m in main drains)
• Less than 10% heavy shading
• Absence of non-native invasive plants or animals
The BNG Value of Ditches
• Distinctiveness: Medium
• Condition potential: Strong, with scope to support diverse aquatic and marginal flora
• Connectivity: Provide vital linear corridors across farmed landscapes
• Climate services: Store water, slow run-off, and trap sediments, contributing to flood regulation
• Time to target condition: 5–15 years depending on water quality and management
Species Typical of Ditches
🌸 Aquatic and marginal plants
• Water violet (Hottonia palustris)
• Pondweeds (Potamogeton spp.)
• Yellow flag iris (Iris pseudacorus)
• Reed sweet-grass (Glyceria maxima)
• Common reed (Phragmites australis)
🐝 Invertebrates
• Dragonflies (e.g. Aeshna mixta)
• Diving beetles (Dytiscidae)
• Water boatmen (Corixidae)
🐇 Mammals
• Water vole (Arvicola amphibius)
🐦 Birds
• Snipe (Gallinago gallinago)
• Reed bunting (Emberiza schoeniclus)
• Pied wagtail (Motacilla alba)
• Mallard (Anas platyrhynchos)
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Frequently Asked Questions
What are Ditches?
Linear, artificially excavated water channels, often for drainage purposes. They can be important habitats for amphibians and aquatic invertebrates, especially in low-lying areas.
How is BNG measured here?
Measured in linear metres. Condition is assessed by the quality of the aquatic vegetation, the profile of the ditch, and the management regime (e.g., rotational de-silting).
How can I achieve BNG?
Enhancement by managing the clearance cycle to retain some established vegetation (rotational clearing), ensuring varied bank profiles, and reducing nutrient inputs from adjacent land.
What is the BNG target condition?
A Good condition involves clear water, diverse aquatic vegetation, and a soft, shallow bank profile, managed on a long rotation to allow wildlife to persist.
What management is required?
Long-term rotational de-silting and vegetation clearance (ideally one side at a time) to maintain flow while ensuring a continuous habitat for species.
Exploring Other Habitats?
Hazel Scrub
Hazel scrub is a native scrub habitat dominated by hazel, typically forming dense multi-stemmed shrubs or coppice stools usually less than 5 metres in height. It commonly occurs along woodland edges, ride margins, hedgerow networks and as transitional scrub developing on former grassland or farmland.
Hazel scrub provides structural habitat for birds and small mammals and produces nuts, catkins and leaf litter that support invertebrates and woodland food webs. It may also function as a transitional habitat facilitating woodland regeneration.
Lowland Heathland
Lowland heathland is a semi-natural habitat dominated by dwarf shrubs growing on nutrient-poor, acidic soils in the lowland zone, generally below about 300 metres above sea level. The vegetation is typically dominated by ericaceous species such as heather, bell heather, and cross-leaved heath, often with gorse species.
Lowland heathland usually occurs as a mosaic habitat, containing patches of dwarf shrub heath alongside acid grassland, bare ground, scattered scrub or trees, and occasionally wet heath or small bog areas.
Bramble Scrub
Bramble scrub is a dense scrub habitat dominated by bramble , typically forming thick thickets between 2 and 3 metres in height. It commonly occurs along woodland margins, grassland edges, road and rail embankments, brownfield land and other disturbed areas as part of natural vegetation succession. All bramble scrub parcels are also recorded as poor condition in the metric, regardless of their structure or species composition.
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