Fen Management Handbook - Scottish Natural Heritage

Distribution of water inputs. The site is bounded on all sides by either minor
(metalled) roads or forestry tracks which have drainage gullies along their sides
opposite to the site (i.e. the upslope side). It was decided that the drainage gully
along the forestry track to the north of the western arm of the site was redirecting
surface water runoff over an extensive reach to discharge at one point into the site,
rather than diffusely along the boundary, and therefore that the western arm of the
site was losing a significant amount of water input.
Hydraulic resistance and water retention of vegetation within the site. Open
mire vegetation, such as bog mosses, will retain more water within the site than
the purple moor-grass which has replaced them, firstly because its specific water
retention is greater, and secondly because the resistance which it offers to lateral
water flow within the site, en masse, is greater. It is therefore very likely that the
change in vegetation within the site has resulted in a reduction in water storage,
and therefore contributed to the reduction in site wetness.
Presence of historical drains. It is known that open channel drains and concrete
pipe drains were installed in the site, but no evidence of their presence could be
found during the site visits. It is considered possible that one or both of these
drainage installations are still partially active in lowering water levels within the site.
Based on the conceptual understanding of the site and the identified negative
influences on its hydrological functioning, a series of measures for hydrological
restoration were recommended, including: targeted remediation of the hydrological
effects of trackside gullies, reduction in the dominance of purple moor-grass, to
the benefit of open mire vegetation and further investigation of the existence and
possible hydrological effects of historical drains.
Continued hydrological monitoring, to allow assessment of the hydrological
effects of the clear-felling of the Broad Meend hillside and a targeted review of the
hydrology and ecology of the site within three to five years, was also recommended.
Acknowledgements:
Liz Laurie and Peter Jones (CCW), Laura Bellis (WMC)
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