Editing River Derwent, Yorkshire (section)

==Course and character of the Derwent catchment area==
For management purposes the catchment area has been divided into ten smaller units.<ref name=CAMS/> Two of these units (Howe Bridge and Ness) relate to the [[River Rye, Yorkshire|River Rye]] which is the subject of a separate article. The other eight, starting at the source, are:
*'''East and West Ayton'''
The Derwent starts its course at Lilla Rig on the [[North York Moors]] a few miles from the east coast of Yorkshire.<ref name=Danby>{{cite book | last = Danby | first = Jack | title = Lilla Cross to Barmby Barrage | publisher = BBC Radio Humberside | year = 1977 | location = Kingston upon Hull }}</ref> After collecting the waters of the Jugger Howe Beck, Black Beck and Troutdale Beck it flows south through the Forge Valley to East and West Ayton. From there it continues across lower ground to where it is joined by the River Hertford. The [[Sea Cut (Scalby Beck)|Sea Cut]], a man made channel, connects the Derwent to the [[North Sea]] near [[Scarborough, North Yorkshire|Scarborough]] to alleviate flooding in the lower reaches of the Derwent, downstream of the Cut. This management area is about 127&nbsp;km<sup>2</sup> and largely rural with no major settlements. Corallian limestone lies beneath this area. The landscape is upland moors in the upper reaches with lower lying flatter land near [[Hackness]]. The river flows through the narrow [[Forge Valley]] and several designated natural conservation sites. Water is retained behind a weir at West Ayton and there are sink holes in the river bed where river water is lost to underlying aquifers, so that in drought years the river below the weir may run dry. There are no wastewater treatment works. The ecology and fisheries have a very high sensitivity to changes in water flow.<ref name=CAMS/>
[[File:Sea Cut Weir , Suffield cum Everley - geograph.org.uk - 67280.jpg|thumb|The Sea Cut Weir drains the Derwent floodwaters to the sea at Scalby.]]

*'''River Hertford'''
The River Hertford starts close to Hunmanby near the seaside town of [[Filey]] and flows westwards into the Derwent. The management area is about 83&nbsp;km<sup>2</sup> with a largely rural economy of arable farming and managed grassland in a flat to undulating landscape. The underlying rock is Corallian Limestone but overlying deposits insulate the river water from this aquifer. Close to the river the land is less than 30 m high whilst to the south of the area on the slopes of the [[Yorkshire Wolds]] it reaches 100 m.<ref name=CAMS/> The river flows in a narrow heavily modified channel. Water is discharged from water treatment works at [[Seamer, Scarborough|Seamer]], [[Folkton]] and [[Hunmanby]].

*'''Low Marishes'''
Having been joined by the River Hertford, the Derwent turns sharply west and flows along the [[Vale of Pickering]] past [[Yedingham]] village. It is joined by the [[River Rye, Yorkshire|River Rye]] four miles upstream from [[Malton, North Yorkshire|Malton]] and then flows southwards. It covers an area of about 273&nbsp;km<sup>2</sup> (105 sq miles) and overlies the Corallian Limestone aquifer. The topography and land use are varied. The flat valley floor is less than 20 metres in height, and here the dominant land use is arable farming. In the northern part of this area lies the [[North York Moors National Park]], where the land is used mainly for upland grazing and forestry. To the south are the [[Yorkshire Wolds]] and here the land rises to over 180 metres in height.
There are waste-water treatment works at [[Thornton le Dale]], [[East Heslerton]] and [[Sherburn, North Yorkshire|Sherburn]].<ref name=CAMS/>

*'''Kirkham Bridge'''
After leaving Malton the river flows south through the steep-sided valley of Kirkham Gorge past [[Howsham Mill|Howsham Mill and weir]] to [[Buttercrambe]].
[[File:Howsham Mill.jpg|thumb|right|Howsham Mill is in the process of being restored.]]

*'''Buttercrambe'''
At Buttercrambe the river continues southwards and through [[Stamford Bridge, East Riding of Yorkshire|Stamford Bridge]].
The above two areas have similar physical and ecological characteristics. They have a combined catchment area of 256&nbsp;km<sup>2</sup> (99 sq miles). Part of the Kirkham Bridge area is underlain by Corallian limestone. The areas are predominantly rural with undulating scenery. The [[Howardian Hills]] lie to the north of Buttercrambe and the Yorkshire Wolds to the east of Kirkham Bridge. There are many scattered villages in the agricultural landscape. The land near the river is less than 20 metres high.
The River Derwent [[Special Area of Conservation]] runs through the length of both areas. There are waste-water treatment works at [[Foston, North Yorkshire|Foston]], [[Leavening]], [[Harton, North Yorkshire|Harton]], [[Whenby]], [[Welburn (Amotherby Ward)|Welburn]] and [[Settrington]].<ref name=CAMS/>

*'''Sutton upon Derwent'''
[[File:Elvington - Bridge small file.jpg|thumb|right|Bridge between Elvington and Sutton upon Derwent (1985)]]
The river continues southwards, cutting through the slightly higher surrounds of the [[Escrick]] moraine and into the [[Vale of York]] and past [[Wheldrake]]. This area covers 79&nbsp;km<sup>2</sup> (31 sq miles). It is low undulating agricultural land; the largest settlement is Stamford Bridge. The River Derwent in this area has many designated riverine conservation sites. There is a substantial public water supply abstraction point in the area which supplies 4.5 million people. There are significant waste-water treatment sites at [[Elvington, City of York|Elvington]], [[Stamford Bridge, East Riding of Yorkshire|Stamford Bridge]] and [[Bugthorpe]].<ref name=CAMS/>

*'''East Cottingwith'''
{{Pocklington Canal map}}
At [[East Cottingwith]] the Derwent meanders across its flood plain still going south, and collects the waters of the Bielby Beck and the [[Pocklington Canal]] which form the major part of the catchment.
This area is 199&nbsp;km<sup>2</sup> (77 sq miles). It is largely rural, having several scattered villages amongst open fields and common land in the [[Vale of York]]. [[Pocklington]] is the largest settlement. The area lies also on the undulating foothills of the [[Yorkshire Wolds]]. Pocklington Canal is {{convert|15.6|km|order=flip}} long and joins the Derwent at [[East Cottingwith]]. In the southern part of the area the land is flat and low. On either side of the watercourse the land is rich and it is farmed as arable or permanent grassland. There are also hay meadows and pastures, known locally as Ings, which form part of the Lower Derwent Valley designated conservation sites. There are waste-water treatment sites at Pocklington, [[Bishop Wilton]], [[Wilberfoss]] and [[Melbourne, East Riding of Yorkshire|Melbourne]].<ref name=CAMS/>

*'''Barmby Barrage'''
At Barmby Barrage the waters of the Derwent are separated from the tidal Ouse to prevent the tides polluting the water extraction plant at [[Loftsome Bridge]]. This area consists of the River Derwent from Sutton upon Derwent lock downstream to the confluence with the River Ouse at Barmby Barrage. It covers 116&nbsp;km<sup>2</sup> (45 sq miles) and it overlies the Sherwood Sandstone major aquifer. It is largely rural, with a few small villages in an agricultural landscape of pastures, meadows and arable fields. There are several designated conservation sites. There are waste-water treatment works at Wheldrake, [[Bubwith]], [[Ellerton, East Riding of Yorkshire|Ellerton]] and [[North Duffield]].<ref name=CAMS>{{cite web |url=http://publications.environment-agency.gov.uk/pdf/GENE0206BKFB-e-e.pdf |title=The Derwent Catchment Abstraction Management Strategy |access-date=25 March 2008 |date=March 2006 |publisher=Environment Agency |url-status=dead |archive-url=https://web.archive.org/web/20080530154329/http://publications.environment-agency.gov.uk/pdf/GENE0206BKFB-e-e.pdf |archive-date=30 May 2008 }}</ref>
{{River Derwent, Yorkshire navigation}}