FAQ - Ditch Management

There are c.1200km of field ditches that criss-cross the Levels, which should be being maintained by individual landowners.

This periodic management includes the need to desilt and manage bankside vegetation growth.

The Gwent Levels is made up of a series of SSSIs located between Chepstow and Cardiff. The nature conservation interests are associated with the network of drainage ditches and reens. The variety of management practices and the timing and location of management within the ditches has led to the establishment of a rich variety of plants and associated populations of invertebrates. 

The Gwent Levels are important for both submerged plant species associated with open water, such as the hairlike pondweed (Potamogeton trichoides), and emergent plants such as arrowhead (Sagittaria sagittifolia).  The invertebrate interest is associated with open water, emergent dominated ditches and flowery banks.

The conservation value of these watercourses is vulnerable to neglect. Where management of bankside vegetation has not occurred for some time, the watercourse becomes overgrown and the SSSI aquatic plant assemblages, especially those that are floating and submerged, are lost. Bramble is a problem on the Gwent Levels as it is fast growing, creating a tunnel of scrub that shades out water vegetation.

The Gwent Levels is now failing in optimal management for its SSSI features as shown by the recent NRW monitoring surveys carried out (NRW 2010-18), which show much of the Levels ditch network double hedged, threatening the aquatic plant and invertebrate interest that the Levels is so important for and that SSSIs are designated for.  The NRW Survey shows that at least 63% of the field ditches across the 7 SSSI’s are heavily shaded.

Overgrown, silted up ditches reduce biodiversity and the flood storage capacity of the drainage system, which could lead to increased localised flooding. Other benefits to management include water and soil quality; protection of buried archaeology; and to increase the range and extent of habitats and species and their resilience to climate change.

The projects aim is to restore approximately 21km of neglected ditches (less than 2% of all ditches) and re-introduce willow pollarding to maintain their longevity in the landscape. Pollarded willows support many species and their lack of management is dangerous, can cause flooding issues when blocking ditches. They are also a key landscape feature of the Gwent Levels, so restoration is in keeping with the character and identity of the area.

When we identify a possible ditch that needs restoring we undertake significant ecological surveys to check for any protected species that helps inform if it is suitable to restore. In addition, all works take place during the autumn and winter to avoid disturbing nesting birds and other wildlife.

Whilst it is understandable that some people may find the work destructive in the short term, it is incredibly important to supporting the rare wildlife found on the Gwent Levels in the long term. From the monitoring work following habitat works, we can already see that watercourses are supporting more plants and animals. This management is improving the biodiversity value of the Gwent Levels, benefiting the SSSI, and will restore the landscape’s traditional mixed mosaic character, particularly by opening up again the areas which have become shaded and dry.

You can see more about the importance of managing ditches and reens by watching ‘Life down the drain’, an explanatory video produced by the former Caldicot and Wentlooge Internal Drainage Board (now NRW):