Fen Management Handbook - Scottish Natural Heritage

Surface water level change e.g.
– a climatic drier or wetter period (e.g. a few years) that is expected to occur
naturally every so often;
– past and recent management or dereliction of water course;
– recent management (or dereliction) of culverts / sluices / outflow valves;
– recent flood management in the catchment (river / lake levels are now different);
– new or changed flood embankment;
– changed variability (frequency and intensity of rainfall events) due to long-term
climate change.
Groundwater level change
– a climatic drier or wetter period (e.g. a few years) that might be expected to
occur naturally every so often;
– changes in groundwater abstraction quantity or location;
– reduced recharge due to long term climate change and land management
changes within the recharge area.
7.1.5 Consider what can be done about the changes
Solutions to redress factors which have negatively influenced hydrology are
summarised below. Practical aspects of lowering ground level and raising water
tables are described in more detail in the text which follows.
Remedy/options Considerations
Problem: Ground water drying up
Remedy: Increase soligenous supply
Raise the water level in the aquifer by increasing
catchment recharge through appropriate land
management.
Decrease abstraction from the aquifer at specific times
and by amounts that will have a beneficial impact on
discharge to the fen.
Artificially increase groundwater level. If possible, and if
reduced groundwater supply is due to a local de-watering
for example, a re-charge trench can be installed between
the fen and the abstraction to raise the groundwater level.
Problem: Surface water, fen too dry
Remedy: Increase topogenous supply
(a) Increase water retention on the fen by restricting
outflow (blocking ditches / changing levels of weirs).
Requires discussions with environmental regulators and
external specialist support.
Normally only realistic where the fen is legally protected
(e.g. SSSI / ASSI or Natura 2000), will require specific
investigations and could be very costly. This will require
discussions with environmental regulators and external
specialist support
Temporary solution and costly in terms of both finance
and energy, but might be the only solution in certain
cases. This will require discussions with environmental
regulators and external specialist support
Standing water may result in anoxia especially in peat or
soils rich in organic matter. Care should be taken that
no standing water remains continually on the surface,
or the fen may change to a swamp which will be harder
to manage. In ‘flow through fens’ such as alkaline fens,
water should be kept moving through the soil. This kind
of management might need consent from environmental
regulators and can affect adjoining landowners.
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