Trillis Wetland Restoration
At Trillis Nature Reserve in the Golden Valley, the Holy Brook and its floodplain had been significantly altered by historical land management. Historic modifications included straightening the stream into a uniform homogenous channel and creating artificially high banks, preventing the floodplain from being functional. The stream bed was also either very slightly perched or level with the floodplain throughout large sections of the site.
In July 20205, Stroud District Council funded a wetland restoration project to infill a reach of the channel, in addition to reprofiling two ponds. The ponds did not hold water throughout the whole of the year, and offered little value to wildlife with steep sides that are not consistent with naturally occurring ponds.
The project aims to restore and create diverse wetland, floodplain, and stream habitats by allowing the Holy Brook to break free from its uniform channel. This will encourage the development of floodplain grasslands, wetlands, and fen habitats – enhancing species diversity and enabling the site to store significant amounts of carbon in the wetter soils. This nature-based solution supports the creation of biodiverse ecosystems that benefit both people and wildlife.
The routes of the public and permissive footpaths will remain. A new bridge has allowed walkers to cross the Holy Brook upstream of where the stream is being re-naturalised, which will offer an alternative route when the floodplain is holding water.
Great fen sedge by Tess Wright
Where appropriate aquatic habitat is available and water quality is good, wetland plants can quickly colonise and rich communities will assemble. Hence, rather than translocating rare plants, it may often be better to see what nature throws up from the past.
If we really want our rivers to be in better health at the same time as protecting ourselves from floods and droughts, which are increasing in frequency and magnitude due to climate change, we need to help our rivers help themselves and give them space. By restoring some of the lost functions of rivers and their landscape connections, we can reinstate key processes that help manage nutrients, sediment, floods and low flows, thus giving rivers some of their resilience back.
There has been growing interest in the ‘Stage 0’ river restoration approach with an increasing number of projects across the UK. River-wetland corridors are important for nature but are also critical zones for flood water storage and processes such as nutrient cycling and energy flows, and they are rich sources of insect life that ultimately feed birds and fish.
A photo before the wetland restoration work. The stream had been pushed to the edge of the field and was disconnected from its natural floodplain by an earth bund that ran alongside the channel. In many catchments, formerly complex river corridors have been modified into straightened channels.
The photo above shows the site before the wetland restoration work took place. The stream had been pushed to the edge of the field and was disconnected from its natural floodplain by an earth bund that ran alongside the channel. In many catchments, formerly complex river corridors have been modified into straightened channels.
New wetland and floodplain habitats, such as fen, will be created. Vegetation diversity will increase with better connection between the stream and floodplain.
Vegetation diversity will increase with better connection between the stream and floodplain. The wetland restoration project will have stirred up the seedbank and in time new wetland and floodplain habitats will establish.
We should do the engineering that is necessary to free up natural processes, and then, so far as possible, stand back. Nature based solutions will help create and restore biodiverse habitats that provide services for people and nature.
We should do the engineering that is necessary to free up natural processes, and then, so far as possible, stand back. Nature based solutions will help create and restore biodiverse habitats that provide services for people and nature.