Gullies & Large Grips

Some of the grips in Yorkshire's upland peatlands have become badly eroded that they can no longer be classed as grips and have become sinuous gullies.

In addition to eroding grips, the impact of drainage combined with other factors such as wildfire and over-grazing have led to the “natural” development of large eroding gullies in many areas of peatland.

Gullies are surveyed by Yorkshire Peat Partnership and the extent of erosion is taken into account when determining how to treat each gully. The main objective is to reduce water flow to enable trapping of sediment at the base or, in larger gullies, stabilisation and revegetation of the eroding, hagged sides. This prevents further collapse and widening of the channel.

How do we restore gullies?

Peat and Stone Dams

Peat dams, as used in small grips, are effective in gullies up to 1m wide. Stone dams (also described on the ‘Small Grips’ page) are used in gullies measuring between 1m and 2m wide to slow the flow of water and trap peat sediment. Yorkshire Peat Partnership carries out a detailed survey of gullies requiring stone dams and identifies a suitable location in the channel for each dam.


Timber Sediment Traps

Timber sediment traps can be used in suitable gullies. These slow the flow of the water without stopping it completely and allow sediment to settle out and build up behind the dams. Untreated timber planks should be used to create a dam no more than 1m high.

The planks should be fastened to supporting posts with the bottom two planks fitting closely together. A gap of 1-2cm should be left between any higher boards so that water can slowly leak through in periods of higher flow.

Turves should be placed along the base of the upstream side of the dam and compressed enough to form a seal between the roots of the turf, the base of the dam and the substrate. A spill plate will be required on the downstream side to prevent erosion of the base of the gully if water spills over the top of the dam.

A V-notch should be cut in the centre of the dam and, where the dam is the same height as the gully, a shallow runoff channel should be created to allow excess water to disperse across the moorland.


Reprofiling

Gullies and grips wider than 2m are too large to dam so Yorkshire Peat Partnership reprofiles the eroding sides, as described on the ‘Peat Hags’ page.


For more details of the techniques above, see the Technical Specifications page.