Floodplain enhancements for fish and fowl
With all the wet, cold weather and flooding at the moment we thought it would be good to look back to some projects delivered last summer for a bit of light relief.
Last summer was a busy time for delivery at with projects delivered at a number of sites including Eythrope and Waterstock Local Wildlife Site (LWS). Waterstock in particular is a special area of the River Thame catchment and was designated a Local Wildlife Site in 2019 ; more recently it was designated an Important Freshwater Area (IFA) as a consequence of the habitats and wildlife found there.
As a whole the river and floodplain of the Thame is an important habitat for a whole host of species, including curlew, lapwing, otter and a variety of fish, plant and invertebrate species. Central to RTCT strategy is an aim to improve habitats along the river corridor by conserving, improving and connecting them. With that in mind RTCT have been working for a number of years with our partners at Freshwater Habitats Trust, and local landowners in Waterstock, to identify and develop projects and plans that would deliver a variety of habitat creation and enhancements in the river and on the floodplain.
Over the past few years RTCT has installed a fish pass and carried out various instream habitat works at Waterstock, as well as designing, developing and delivering a number of other projects:
Habitat feature 1: Backwaters
After several months of planning we were able to break ground and create 3 new backwater habitats. Backwaters are essentially ponds connected to the river and are important in providing areas of still water as a refuge for fish, in particular fish fry which thrive in their warm, shallow waters. They also create excellent habitat for wetland birds, plants and invertebrates. Originally meanders that had become isolated from the main river and other similar features would have acted as backwaters, but many of these habitats have been lost due to straightening, drainage activities and other man-made impacts.
Habitat feature 2: Scrapes
Alongside the backwater works carried out by RTCT, Freshwater Habitats Trust created two wetland scrapes on the floodplain. These are shallow depressions that are carefully located and designed to hold clean rain water and provide clean water habitat (as well as retain floodwaters for longer after heavy rainfall periods). This habitat is important for plants, particularly those sensitive to the pollution in our rivers, as well as invertebrates and wetland birds. The occassional flooding of the features by polluted flood waters is mitigated by drying out seasonally, allowing nutrients to be lost and ensuring clean unpolluted water for at least some of the year.
Creating the habitats
Backwaters and scrapes in simple terms are about creating holes and hollows on the floodplain and the rivers edge. Although simple in principle there is a lot of thought and design that goes into getting it right. It is important to ensure the correct location is chosen and that levels and slopes are just right to ensure the features will operate effectively.
After months of planning, design, obtaining permissions and overcoming unforseen issues it was great to actually break ground!
A 22 tonne machine was used to dig the backwater. Soil was removed from the floodplain and spread evenly before being covered in topsoil and seeded.
Unlike larger features like backwaters, shallow scrapes of a certain size don’t require the spoil to be removed from the floodplain. Therefore, creating the scrapes allowed us to use a different kind of earthmoving machine – a rotary ditcher. Rotary ditchers essentially cut, dig and spread earth away from the site in one process. They are useful for shallow scrapes and certainly look impressive and fun in action!
All these features will now be monitored over the coming years to see how effective they are. With all of them currently totally covered in flood water this is not an easy task. What a winter we are having!
Thanks to all those who helped make these projects happen including:
Thank you to Andy Killingbeck, Cat Robinson and Kay Lidgard at the Environment Agency for their help and advice during the backwater projects work up phase
Landowners Henry Manisty and Stephen Shipperley for their support and enthusaism
Contractors – Backwaters
James Gillies Consultancy (small backwaters)
Contractors – Scrapes