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The Colne is a river in England which is a tributary of the River Thames. Just over half its course is in south Hertfordshire. Downstream, the Colne is the boundary between Buckinghamshire (specifically the South Bucks district) and London (specifically the London Borough of Hillingdon) and finally between corners of Berkshire and Surrey. On leaving Hertfordshire, the watercourse splits off into several separate branches, a few of which rejoin it, and its main branch flows into the River Thames on the reach above Penton Hook Lock at Staines-upon-Thames. Two further, artificial distributaries were constructed in the 1600-1750 period for aesthetic reasons for Hampton Court and for Syon Park which have been kept maintained, flowing through several London districts. Although their main purpose was not drinking water, these artificial streams can be likened to the New River in scale and in date. Crossing its route, viaducts and canals, such as the Grand Union Canal have been recognised for pioneering engineering during the Industrial Revolution. Digging for gravel and clay along its lower course south of Rickmansworth has created a long belt of pits which have flooded to become lakes. Many of these are important habitats for wildlife and protected as nature reserves. Its course, meadows and many once gravel-producing lakes form the Colne Valley regional park which is slightly smaller while in London than the Lea Valley Park however more than twice the size overall, at . ==Route== The Colne rises perennially from a subterranean river at a spring in North Mymms Park in Hertfordshire. Two occasionally dry tributaries: an unnamed brook and the Mimmshall Brook start from the source at golf courses in Barnet, at Borehamwood and in fields by Northaw Place, Northaw.〔Grade II * architectural listing of Northaw Place 〕 This underground stretch under the old six-building village centre of North Mymms runs for 〔(Brookman's Walks )〕 〔(Ordnance survey website )〕 from swallow holes of the two brooks in the part of that parish named Water End. From the Water End Swallow Holes the Colne runs NW then SW, bounding central and residential Watford and Oxhey, also bounding Rickmansworth and Batchworth, then marking the border between Greater London and Buckinghamshire. After these conjoined settlements it turns south, its main direction, and passes between West Hyde, near Maple Cross, and Harefield, passes Denham Green then passes Uxbridge where it parallels the Grand Union Canal and its distributary the Frays River which is joined later by the River Pinn between Cowley and Yiewsley on the Greater London side. The Colne Brook splits off as a distributary between New Denham and Uxbridge, after this at West Drayton the Frays River rejoins and the Wraysbury River and Duke of Northumberland's River divide off. In its lower reaches, the river at Longford supplies water to the Longford River, a artificial channel created in 1610 for King Charles I to supply the water features in Bushy Park and the rectangular lakes in Hampton Court Park.〔(【引用サイトリンク】title=Bushy Park )〕 The Colne's drainage basin extends almost as far north again as the main stream of the river beginning in Hertfordshire: its tributaries, including the Gade, Ver and Misbourne, all extend well into the Chilterns. The Colne's drainage basin is bordered by a range of Thames tributaries to the east and west, including the Crane, Brent and Lea to the east and Wye to the west. To the north of Tring a modest ridge acts as a watershed, separating the Colne's drainage basin from that of the River Great Ouse, which flows north and east towards the Wash. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「River Colne, Hertfordshire」の詳細全文を読む スポンサード リンク
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