Fen Management Handbook - Scottish Natural Heritage

At Leighton Moss in Lancashire, areas of open water are regularly
maintained or created by cutting reed below water-level in summer
either by hand or with a mower where the ground is firm enough. An
alternative is to cut close to the peat surface and raise the water level
shortly afterwards. Flooding the cut stems kills the plants as they are
unable to get air into the underground rhizomes from the stems and
leaves. This approach has also been used for controlling invasive soft
rush.
The Broads Authority have used an amphibious machine called a Truxor
which has a number of inter-changeable heads, one of which is used for
cutting vegetation under water. This machine has been used on flooded
fen at Reedham Marshes and at the RSPBs Strumpshaw fen.
7.4 Raising water levels
Fens can be restored or rejuvenated by appropriate adjustment of water supply
to re-wet rather than flood the site. This approach was adopted at Shirley Pool in
Yorkshire, where water was pumped experimentally onto the site from an adjacent
watercourse for a short period (Roworth & Meade 1998). This significantly
increased the level of the water table for relatively little expense for the few weeks’
duration of the experiment. Alternatively, a wind-driven pump can be used, as for
example at the private nature reserve at Rodley.
Water levels can be raised by impeding the natural egress of water entering the site
through groundwater seepage, surface flow, and/or from rainfall. This may simply
involve raising the water level in drains and other ditches, but in some cases the
water will simply overtop the edge of the drain and exit by another route rather than
raising soil water levels.
An appreciation of surface contours can be gained from ground survey or by the
interpretation of remote data such as LiDAR (Light detection and ranging) which
involves the emission, reflection and detection of light radiation using airborne
or ground-sited equipment. LiDAR can record vertical differences of a few
centimetres (ground-sited) but its accuracy is dependent on there being gaps in
vegetation through which the ground is visible. Any programme of ditch-damming
or bund creation will benefit from the use of such information.
Pumping water into Ham
Wall RSPB reserve to raise
the water table (RSPB).
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