River Management Techniques. Upper Wharfedale Best Practice Project (Information Series No 6)

7.2. Tree maintenance/management

7.2

LOCATION:
Redmire, SD 943759

LENGTH: c.50m

DATE UNDERTAKEN:
Autumn 2001

COST: c.£1,000

BACKGROUND INFORMATION

During the 1980s work was undertaken in this area involving the planting of willows to protect against river bank erosion. This is a well-established method of providing a soft revetment and has worked very successfully at this location. However, the species of willow used (osiers) were imported to the area from a lowland river and, after twenty years of unmanaged growth, stood out as being alien to the landscape.

DESCRIPTION

The site is on the outside bend of a tight meander loop in the river. The river bank at this location had been re-engineered around the time the trees were planted. Lack of subsequent management was evident by leggy growth in the trees, allowing erosion to start at the base of the willow trees and encroaching into the river bank behind.

DESIGN

Ideally it was hoped the osier willows could have been removed entirely from the site and replaced with a variety more in keeping with other species found in the area. The need to maintain existing river bank protection remained an important issue, however, and led to a decision being taken to retain and manage the existing osiers.

SPECIFICATION

The entire stand of willows was coppiced down to ground level. Brash from the felling was tied into the bare eroding bank at the base of the trees to attract silt deposition and the eventual reestablishment of ground cover vegetation.

An otter holt was incorporated and goat willow and ash planted to diversify the stand.

On other stretches of the river, spiling works 700mm above normal summer water level, installation of 600mm long goat willow stakes of 40mm average diameter and 200mm willow and birch faggots filled to a height of 1m from the river bed behind willow and soft wood piles were techniques used.

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