River Mimram
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The Mimram Valley is named after the River Mimram, which rises from a spring near Whitwell, in North Hertfordshire, UK, and makes it's confluence with the River Lea near Horn's Mill in Hertford.
The valley floor of the River Mimram is characterised by extensive flood meadows. The land is given over to rough grazing mainly cattle with some horse grazing adjacent to houses and farmsteads. The field pattern is largely lost through grazing out of hedges, leaving remnant hedgerow trees and replacement post and barbed wire boundaries. Mature trees are scattered throughout the area with the only notable woodland to the north. Species mix is dominated by willow and poplar. Vegetation frames views and allows occasional glimpses down the river corridor. The smaller, more intimate scale of the landscape is emphasised by the enclosing large-scale arable landscape.
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[edit] Physical Influences
[edit] Geology & soils
Poorly draining gleyed soils over alluvial drift underlain by chalk locally outcropping.
[edit] Topography
Flat valley bottom.
[edit] Degree of slope
Typically 1:10 on valley slopes with a fall of 1 in 500 along this section.
[edit] Altitude range
74m to 84m.
[edit] Hydrology
Over the lower reaches the Mimram is a comparatively fast flowing chalk stream. However, in June the upper reaches are dry at Hoo Park. Springs from surface outcrops of chalk. Land cover and land use Land used mainly for grazing but with extensive areas of wetland vegetation and some arable.
[edit] Vegetation and wildlife
Predominant semi-natural vegetation types are neutral alluvial grasslands, mixed tall herb fen and remnant alder/willow woodlands. Ecological interest within this Character Area reflects the influence of the River Mimram. The Hertfordshire Biodiversity Action Plan describes the river stretch between Kimpton Mill and Fulling Mill, as being of high biodiversity value. The calcareous springs of the Mimram are of some importance including the springs at Stagenhoe Bottom, the cress-bed springs at Nine Wells and the seasonal lake at Law Hall Farm. An interesting wet woodland site occurs adjacent to the River Mimram in proximity to Kimpton Hoo. Tall fen vegetation occurs beneath a mixed wood canopy that includes cricket bat willow, poplar plantation and hazel coppice. Species rich grasslands on alluvial soils are present by the River Mimram in the vicinity of Kimpton Mill and further along the riverbanks to Codicote Mill. Mimram Valley Marsh supports an array of wetland habitats, including sedge and reed beds, marshy grassland, derelict watercress beds, old plantations and some acidic grassland communities. Fulling Mill Meadow incorporates wet and dry habitats ranging from swamp through to old unimproved grassland. Wintering water rail, kingfisher and grey wagtail are associated with the springs and river at Kimpton Mill.
[edit] Historical and cultural influences
[edit] Field pattern
The historic agricultural landscape pattern consists of a mixture of post 1950s enclosure, prairie fields with 1950s boundary loss and pre-18th century irregular enclosure. Today there is no apparent field pattern, there are, however, post and wire fences to control grazing.
[edit] Transport pattern
The Kimpton Road runs parallel to the river following the southern boundary to the area. A small number of local lanes ford the river. Settlement and built form the historic settlement pattern, this is sparse with no documented traditional buildings. Indeed structures and building limited to the Mill at Codicote and Rye-end Farm.
