User:Jokulhlaup/Henmore

{{Geobox|River}}

Confluence

Source

Ashbourne

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Map showing the location of Source and Confluence with the Dove and Ashbourne within Derbyshire

The Henmore Brook or the River Henmore is a tributary of the River Dove in Derbyshire, England, and is 20km (12 miles) in length.

In its upper reaches it is known as the Scow brook, much of which was inundated by the Carsington Water reservoir in 1991. It takes the name of Henmore brook in the middle reaches, where there are three tributaries called the Parkside, Kniveton and Dayfield brooks.

The brook drains a catchment of mixed geology, which has an area of 46 square kilometres (18 square miles). It flows through the market town of Ashbourne, where flooding of the town centre by the brook has historically caused significant damage. The brook is designated as a Main river by the Environment Agency from the outflow at Carsington Water to the confluence with the River Dove.

Course

The source of the brook is at the base of Soldiers Knoll near Stainsborough Hall, from where it flows west until it reaches the upper end of Carsington Water near Hopton. It reappears at the outlet of the dam, and flows in a south-westerly direction past the villages of Hognaston, Atlow, and Sturston until it reaches the town of Ashbourne. Downstream of the town it passes the village of Clifton before reaching its confluence with the River Dove at Church Mayfield.

Name

The name Henmore is modern, first appearing in 1693.The brook is often called the River Henmore in the town of Ashbourne, especially in relation to the RSF match.

History

There has been a long history of human presence and settlement in the Henmore valley, with many Palaeolithic sites both in the north near Carsington, with round barrows and standing stones, and other tumuli in the sandstone hills south of Ashbourne. A rare Acheulean stone axe was found at Hopton.

Early lead mining in the catchment was important enough that a significant Roman settlement was established. This was discovered during archaeological digs that took place beside the Scow Brook prior to the area being inundated by Carsington Water. A Roman lead ingot or 'pig' weighing 69 kg was also discovered nearby in 1946.

Ashbourne or Essenburn (a brook where ash trees grow) was included in the Doomsday book, and became an important medieval market town, with the road linking Derby to Manchester crossing the brook in the town. The farming community in the Henmore valley supplied the produce for the markets, such as cheese.

The brook also passes alongside Atlow moat, a well preserved example of a medieval manor homestead moat and which was once the home of the Atlow family. There was also a substantial corn mill at Atlow driven by the Henmore, but unlike other mills along the brook the buildings have been renovated for modern use.

The Henmore was not employed for cotton spinning during the industrial revolution, which is unusual for a Derbyshire brook, although a number of large cotton mills were established at Church Mayfield where the Henmore meets the River Dove. There were, however, at least two corn mills near Ashbourne that were powered by the Henmore brook at Clifton and Sturston. Although subsequently demolished, they have become the goals for the annual Royal Shrovetide Football match.

Hydrology redo

The hydrology of the brook is heavily influenced by its geology, topography and Carsington Water.

The impermeable shales and mudstones that make up the majority of the catchment, combine with its steep topography and moderate rainfall to produce a responsive drainage basin. The average rainfall for the Henmore is 894mm, which is similar to the average for the wider Dove catchment. The maximum elevation of the basin is 392m, giving a fall of 300m over its short 12km length.

It is notable that there have been a number of floods in Ashbourne after the construction of Carsington, revealing that it has a minimal affect on larger events, the dominant factor being the high runoff potential of the catchment as a whole.

During periods of low rainfall the reservoir provides a steady compensation baseflow of 0.05 cubic metres per second to the brook.

Although the flow of the brook is subdued by the presence of Carsington Water in its upper reaches, Ashbourne has remained prone to inundation, due to the responsive nature of the remaining catchment. The compensation releases from the reservoir provides a steady base flow of 0.05 , during normal conditions. The annual average rainfall for the catchment is 894mm.

Geology and Land Use

Geology

The catchment drains an area of varied, drift free geology. Sandstones of the Sherwood group underlie the area to the south of Ashbourne, with Millstone grit to the north-west, whilst the upper reaches are of Carboniferous limestone. In some areas of Derbyshire, including the upper Henmore, this limestone has been subject to basaltic intrusions, which through a process known as hydrothermal mineralisation, produces veins of minerals such as galena or lead-ore. These veins or rakes were mined in the Carsington area.

In terms of land use the catchment is mainly rural, apart from the town of Ashbourne, and surrounding villages. The predominant land use is pasture for grazing, which accounts for nearly three-quarters of the catchment area, with some arable farming, the remainder being the area covered by Carsington Water and woodland.

The Geology of the parish is of Sedimentary Mudstone - the Charmouth Mudstone Formation - overlaid with postglacial sands and gravels. The bedrock of the higher ground at Barkston Heath is from the Great Oolite Group of sedimentary rocks - Sandstone and Limestone.

Ecology

The brook provides an important wildlife corridor and contains species which are indicative of a healthy ecology, including hares, water voles and otters. It is renowned for its population of water voles, with a large colony outside of Ashbourne. Evidence of otters has been regularly found downstream of Ashbourne and occasionally upstream, the brook having been described as having a Riffle and pool bed form which is ideal for otters.

The dam at Carsington Water effectively cuts-off the upper section of brook in terms of its ecology. The reservoir itself and its surroundings does however, have a good record of water bird sightings.

Flooding

The Henmore brook has a history of flooding Ashbourne, which has led to a number of changes in the town to reduce its reoccurrence. Following the floods in 1960, the brook was widened and culverted at Shaw Croft in the centre of the town, with the memorial gardens, recreation ground and Fishpool meadow being altered so that they would act as a flood storage area.

Although the construction of Carsington Water in 1991 meant that later floods were reduced, Ashbourne remained susceptible, with further flood events in 1998, 2000, 2007 and 2008. These floods revealed that the existing defences were inadequate, and they were subsequently improved and extended in 2012, giving the town a higher level of protection.

In addition, the Environment Agency operates a flood warning system for the lower Henmore, informing residents and local authorities of possible flooding events..

Royal Shrovetide Football

The Henmore brook, or as it is usually called in reference to the game, the River Henmore, is an integral part of the Shrovetide football game of Mob football. It determines which team the player joins or supports, those born north of the Henmore are the Up’Ards and those born to the South are the Down’Ards. It links the two goals at Sturston and Clifton, and often acts as the pitch as well. This was reinforced in 1996 when to make the game more challenging, the two goals were repositioned on the banks of the river, which meant players needed to be in the river to ‘goal’ the ball.

Up'Ards purpose-built goal at Sturston Mill

In 2011, play even continued through the culvert beneath the Civic Square. Once out of the town, the banks of the river provide good viewpoints to observe the match.

Fishing

Historically the brook was noted for its excellent fishing. (1868 gazette). This continues today, with a fly fishing club catching brown trout and grayling around Ashbourne, the same two species mentioned in 1868.