Chalk stream at West Beck Copper Hall
The UK’s chalk streams are our equivalent of rainforest. We must maintain, improve and enhance these special habitats. Here we highlight why chalk streams are a unique feature of east Yorkshire’s landscape.
What is a chalk stream?
Chalk streams are essentially spring fed rivers and are globally scarce with over 90% of them found in the UK. Around 70 million years ago in the cretaceous period, thick layers of sea shells were deposited in areas of eastern and southern England that were at that time under the sea. The main component of this crushed sea shell is calcium carbonate, otherwise known as chalk. This is the main rock found in the rolling hills of the Yorkshire Wolds and the source of the water that feeds our chalk streams.
As the (slightly acidic) rains fall on the Wolds they pass into the chalk rocks, which critically are porous and act like a huge sponge, soaking up the water and preventing it from flowing directly over the surface and straight into the streams. As the water passes through the chalk it is filtered and becomes alkaline and crystal clear.
The chalk sponge (known as an aquifer) slowly fills up and the pressure of water builds until it is forced out of the ground as springs, first forming small streams before joining up with other spring streams to create the larger streams and becks that flow towards the sea.
East Yorkshire’s chalk streams
In East Yorkshire the majority of the chalk streams start and rise as springs around the market town of Driffield to create the two main watercourses, one flowing from west to east; starting as Eastburn and Elmswell Becks before becoming Driffield Trout Stream and finally West Beck, with the other flowing from north to south; starting as Lowthorpe Beck and changing its name as it passes through the parishes of Kelk, Foston and North Frodingham.
Collectively the chalk streams around Driffield are known as the River Hull headwaters chalk streams and the River Hull is recognised as the most northerly chalk river catchment in the UK. The importance of these chalk streams is recognised by the fact that they are designated a Site of Special Scientific Interest (SSSI), overseen by the government agency responsible for nature conservation that is Natural England.
These two main watercourses join up south of Driffield to form what is known as the River Hull and flow due south into the Humber estuary at the city of Hull.
There are also a scattering of smaller chalk streams that flow from the western escarpment of the Wolds to the Derwent, including Riding’s Beck, Nunburnholme Beck and Bishop Wilton Beck. These small tributaries of the lower river Derwent all flow largely independently of each other but all the chalk streams of East Yorkshire are linked by their dependence on the chalk aquifer that is the Yorkshire Wolds.
Why protect our Chalk Streams?
The UK’s chalk streams are our equivalent of rainforest and deserve a huge effort to ensure we maintain, improve and enhance them.
As well as being amazing places for wildlife, chalk streams provide the drinking water that we take for granted with the chalk aquifer providing large volumes of water used in irrigation of our arable crops on the Wolds.
Over 70% of our chalk streams are failing to meet the ‘good ecological status’ target as set out in the EU’s Water Framework Directive (WFD) with high phosphate and nitrate levels in the aquifer.
Other direct threats to the streams include pollution from sewage, septic tanks and agriculture, spread of non-native invasive species, over-abstraction of the ground water leading to dangerously low flows in summer and physical changes combined with poor understanding and management of chalk streams over recent decades.
What are we doing?
Yorkshire Wildlife Trust launched its project, Crystal Clear – Restoring the Chalk Streams of the River Hull in late autumn of 2013, thanks to 3 years funding and support from the WREN Biodiversity Action Fund (BAF), alongside other external funding from the Environment Agency and matched funding from the Higher Level Stewardship agri-environment scheme as administered by Natural England.
The main aims of the project are to work at 6 locations on the west east arm of the River Hull headwaters chalk streams to restore degraded sections of stream, enhance adjacent wetland habitat and create new wetland habitat to create a buffer alongside the streams.
The work programme sits within our River Hull Living Landscape and forms a key component of our strategy within the River Hull catchment to join up fragmented wildlife habitats creating corridors for species to spread and move across the landscape.