What were the issues?
Hawkhill and Furzey Lodge Mires are both on the Open Forest north of Hatchet Pond.
The Hawkhill site supports a large valley mire which has been damaged by past drainage operations. A main channel drains two areas of the western mire before flowing into Hawkhill Inclosure, while a deep drain takes water from the eastern mire into a drain running along the Inclosure fenceline. These artificial drain lines were causing the loss of mire vegetation and underlying peat and gravels through headward erosion.
Headward erosion can arise when there is a sudden drop in gradient, usually where artificial drains have been dug. The drains lead to a faster, more erosive outpouring of water from the mire, together with localised turbulence at the junction of the mire and drain. As a result, the drain actually erodes back into the mire, with a resultant loss in area of an internationally protected habitat.
The site at Furzey Lodge supports a small seepage mire in the east and a larger Y-shaped valley mire in the west. An over-deepened drain below the seepage mire had developed a nick point and there was headward erosion into the mire. The Y-shaped valley mire was in reasonably good condition but some minor works were needed to repair a small nick point and a stock crossing point.
How did we fix them?
At the Hawkhill site, we infilled the main drainage channel from the nick point in the west for approximately 100 metres, to reduce the erosional force of the water. We also repaired other smaller nick points found in the adjacent mire vegetation.
This work has enabled the mire to hold water back, allowing water to spread over damaged areas and aid recovery of the mire vegetation. In the eastern mire, the drainage channel was infilled and repairs were made to the passageway and existing culvert.
At the Furzey Lodge site, we infilled the western channel draining the seepage mire, starting at the nick point and continued northwards for about 20 metres, to reduce the erosional force of the water.
We also repaired the large hole and nick point that had developed further downstream, and infilled short sections of drain here to prevent any further nick points from developing.
In the valley mire, we infilled approximately 10 metres of drain to repair the eroding nick point and carried out minor repairs to the stock crossing point.