Ditch BNG Units
Medium
Watercourse
Trusted by Developers and Landowners
What is
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
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?
Upland Hay Meadow
Upland hay meadows are species rich grasslands dominated by a mix of fine grasses and abundant herbaceous wildflowers such as sweet vernal-grass, wood crane’s-bill, great burnet, pignut, and lady’s mantles.
These meadows have developed through long term traditional management that combines light grazing with a late summer hay cut. Rare species including lesser butterfly-orchid and burnt orchid are sometimes found.
This habitat is a dense mix of grasses and a wide variety of wildflowers, with no single grass species dominating the vegetation.
Upland Calcareous Grassland
Upland calcareous grassland is a springy, species-rich habitat occurring above approximately 250–300 metres on lime-rich, or “base-rich,” soils. The habitat develops as a short, species rich sward of calcicolous grasses, herbs and orchids adapted to alkaline conditions and cooler upland climates
The grassland appears patchy and open, with fine grasses, colourful herbs and scattered rock outcrops. Wild thyme, common rock rose and bird’s foot trefoil often grow alongside sheep’s fescue and upright brome, creating a varied mosaic.
Upland Acid Grassland
Upland Acid Grassland is a mix of fine grasses, mosses and small herbaceous plants adapted to low pH and limited nutrients. This habitat appears as an open grassy landscape, often dominated by mat grass or purple moor grass. Texture and color come from all patches of tormentil, heath bedstraw and scattered mosses.
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