- 10th February 2021
- Posted by: Dom Senior
- Category: Projects
Location: Thorne, Crowle and Goole Moors
Client: Tween Bridge Internal Drainage Board
In 2009 we were tasked by a consortium of Internal Drainage Boards (IDBs) to produce and implement a £2.9 million Water Level Management Plan (WLMP) covering Thorne, Goole and Crowle Moors, England’s largest terrestrial Site of Specific Scientific Interest (SSSI).
Home to a number of rare species, the mire had been damaged by several hundred years of peat extraction and the aim of the WLMP was to identify restoration measures to bring the site back to a favourable condition. This included ensuring the correct depth of water required to permit the growth of Sphagnum mosses was maintained across the site, despite its varying topography.
The complex nature of the site and its location posed further challenges when designing and implementing the restoration plan. With the area recognised as an SSSI, covering three counties, and owned by 22 separate landowners, any plans could not be implemented without significant stakeholder engagement. Therefore, implementing a plan across the whole site had to consider the sensitivity of the site, the views of a range of stakeholders, and the permission requirements that the complex pattern of administration brought.
Taking such a complex scheme from baseline assessment through to implementation involved a number of stages, including initial assessments and concept design work, embarking on an extensive stakeholder engagement scheme and the installation of an Archimedes screw pump.
However, one of the main innovations for this project was the creation of an “electric bog”, which allows water levels across the site to be managed remotely. Achieving this required the use of innovative technology, telemetry, water level control structures, contour bunding and vegetation management, to monitor and control the water levels on the bog in real time.
To implement this the mire was subdivided into a series of compartments, each of which was bunded with a fixed output weir controlling the water depth throughout the compartment. Groups of these newly created compartments were then linked together in chains downstream with piezometers measuring water levels at set points within the chain. This information is then sent via radio to a central system, which is connected by a mobile phone signal to a central programmable database. A series of tilting weir structures to control the flow of water through the chains of compartments and, at the very bottom of the system, a pumping station, is also connected to this central database.
The newly installed structures are fitted with water level monitoring and are pre-programmed to respond in set ways when rainfall amounts are recorded or when water levels in compartments reach specific levels at certain times of the year.
Through our use of telemetry and the newly created structures to control water levels on the bog in real time, we were able to facilitate the growth of Sphagnum moss and other peat-forming species.
The real-time data collected can also be analysed and used to refine how the structures automatically respond to rainfall and water levels on site, which is essential as over time the bog is highly likely to become wetter at certain times of the year and even change shape. Flowpaths across and through the bog are also likely to change, highlighting the importance of recording and analysing live data and adopting a flexible strategy.
The gradual raising of water levels has not only accelerated the growth of Sphagnum moss and other peat forming species, Eriophorum angustifolium rhizomes have also been able to produce new plants, binding the peat and preventing desiccation, exfoliation and subsequent wind erosion. These plants, and rows of Birch brash, are also now acting as foci for Sphagnum cuspidatum colonisation, keeping the surface wet, allowing the vegetated area to increase annually, closing the sward gaps and ultimately forming an actively growing surface.
As all of the monitoring equipment on site, as well as the structures themselves, are powered using photovoltaic cells linked to a battery (and solenoid in the case of the structures), it also reduces the need for costly and potentially dangerous site visits.
Our innovative approach to this project and the creation of an “electric bog” also led to us being nominated for (and winning!) a number of awards at the Chartered Institute of Ecology and Environmental Management Awards 2020. Our Thorne Moors Water Level Management Plan was awarded the Best Practice Award for Large-Scale Practical Nature Conservation, as well as the highly prized Tony Bradshaw Award for Outstanding Best Practice, which recognises exceptional projects that set an overall impressively high standard.
Want to know more?
For more information about our success at the CIEEM Awards 2020, visit our news page.