River Ash, Surrey


The River Ash is a small, shallow river in Surrey, England. Its course of is just outside Greater London. Work has been carried out to re-align, clear, build up a small, central broader head of water and create very small corollary channels over centuries. It flows as one of the seven present distributaries of the River Colne from the south of Staines Moor immediately south of the Staines Bypass eastwards through the rest of the borough of Spelthorne before meeting the River Thames.
It is not navigable to craft and is rich in plant and insects, particularly reeds, diverse sedges, pond-skaters and lepidoptera.

Course

The river is a distributary of the Colne. It forms the traditional boundary of Staines-upon-Thames first with Stanwell then with Ashford. It then turns southward and splits Littleton from Laleham. It then resumes eastward. It is the northern limit of diminutive, near-square Shepperton Green — which is a renaming due to Shepperton gaining its railway station as was of centuries an outcrop of Littleton, and remains so in the Anglican church system. Eighteen-hole Sunbury Golf Course on high-landscaped former municipal waste landfill then opposes a little of Shepperton across the banks. Then a farm of Green Belt straddles the river partly in outer lands of Sunbury-on-Thames. The river joins the Thames, flowing gently into the Creek - a secondary weirstream of the Thames - facing a long residential island: Wheatley's Ait. Parks make use of it: Fordbridge Park and Splash Meadow. It marks two streets' garden ends, many of which have built footbridges. The five urban centres in the borough are well over 500 m away, which has spared it from pollution and supported its biodiversity. Three parks make use of the river for walks, the longest of which is in Fordbridge Park, Ashford. Even adept canoeists avoid the river when deep enough due to short barrages, extreme narrows and culverts.

Flow

In terms of flow of the seven distributaries, it is mid-ranked:
Alluvium on gravel is the soil setting of the north bank, west of the City of London as far as the Chiltern Hills. As to topsoil the river marks a divide between permeable shallow gravelly topsoil for many miles to the north and almost impermeable alluvium to the south. A very thin, agriculturally prosperous alluvial belt by the River Thames to away was caused by deposition from seasonal floods. This prevents for the whole course the rivers joining despite their proximity. As the gravel former terraces of the Thames very gently slope from north to south no abrupt halts to the water table exist no springs arise and only modest interaction with the Thames Basin's water table. The sources are water from the Colne and run-off principally of a fresh water waterworks. Water quality is ordinarily very clean given improvements in the effluent treatment works along the quite populous Colne valley - for a low-gradient river eutrophication and deposition is moderate to low.

History

gains its name from the river, forming the southern limit of all but its east. Maps featuring the Ash date to medieval times, showing course changes, some clearly man-made. The earliest known shows the history of various courses by Shepperton Studios, a map commissioned by the Lord of Shepperton Manor, two miles to the south. This refers to the monks of Westminster, who had widened from the Colne was moved back south. Further east; 100 metres is diverted to make way for the Staines Bypass . It then flows underground for 270 metres beneath the Crooked Billet roundabout.

1947 and 2014 flooding

The narrow Ash floodplain flooded in 2014, on which a large minority of homes and outbuildings flooded. The previous such instance was in 1947 when inland flooding was widespread across the region. These were due to inadequate flood prevention measures of the Colne catchment, compounded by high water levels on the local parts of River Thames which flooded more homes and saw saturated water tables.
The local authorities after two years of exploring options, ruled out an inquiry to make effective recommendations due to their limited powers to investigate and control co-causatory entities including companies, chiefly upstream. Out of date records meant finding full causation was prohibitively complex.

Flood risk alleviation

Upgrade of the fresh water treatment works at Ashford Common by Thames Water Utilities caused greater steady outflow east of the M3. This heightened flood risk to properties abutting in Shepperton. Public budget work then arose, the River Ash Flood Alleviation Scheme of the Environment Agency. Deep holding troughs exist before the works run-off discharge and in Sunbury Golf Course a relief channel exists, bridged twice, built in January to May 1995 for £450,000.

Listed bridge

A long two-arch bridge has substantial neat stone-dressings, such as seven ballusters across six lightly recessed stone panels, each side, each arch. It has statutory protection and recognition in the initial starting category, Squires Bridge. It was built in about 1870, partly by commission of the Wood family whose manor house standing at today's Shepperton Studios had a costly fire in 1874. Its central newel as to its outer, upstream side has a coat of arms with three swords, not the family's which was that of a bull, instead that of Middlesex.