Hydrology |
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Research & Data:
From this page:
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The Bourne Stream is fed by a number of sources but there is little documentary evidence and the actual origins of some are unknown. The head of the stream consists of four culverts emerging from below Ringwood Road; it is believed that one drains Canford Heath, one is fed from the Bournemouth & West Hampshire Water works at Francis Avenue (more below) and two are supplied by road runoff. The stream is also fed by natural seeps and flushes, and by 62 documented surface water discharges to the watercourse. |
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An in-depth study of the stream's sources and hydrology was carried out in March 2006 for the Bourne Valley SSSI Water Level Management Plan (more here) |
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Bournemouth & West Hampshire Water (BWHW) BWHW Alderney works are positioned close to the head of the Bourne Stream in Alderney, and there is an ongoing daily background discharge to the stream of approx. 0.6 megalitres (ML) - that's 600,000 million litres/day - some 7 litres/second (l/s). As an indication of what that means to the hydrology of the stream, average dry weather flow measured at the Branksome Wood Road gauging weir is about 37 l/s. The water discharged is from the Stour & Avon, which are chalk rivers. The water flows through a wet acid heathland environment, designated SSSI. The resultant mix has had an impact on the type of instream and bankside vegetation found in the Bourne Valley. The slow sand filters used in the water purification process at the Alderney site need to be backwashed to remove the build-up of matter. The water used in backwashing (perhaps for 4-5 days in a month) is drained into two settling tanks and discharge through aeration baffles into the surface water drainage system. The discharge during this period tends to increase to between 1.2 - 1.6 ML/day (13-19 l/s). When filters run to waste the discharge is greatest - perhaps 2.5 ML/day (29 l/s). The discharge from BWHW may well be the primary source of water for the stream during periods of drought. |
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Stream Water Levels & Flow Data Stream Water Levels & Flow Data data are supplied by the Environment Agency, measured at the gauging weir at Branksome Wood Road, Bournemouth, a short way downstream of where the two main tributaries converge in Coy Pond Gardens.
Measurement: m3/second. |
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22kb - shown
as a graph, and compared with local rainfall 
