557:. This location was chosen as it was on a section of the river where flow could be readily measured and above the very flat stretch that meanders into Cheshire. The current rules state that when flow exceeds 10 cubic metres per second (860,000 m/d) no intervention is required. In practice some adjustment of Bala sluices may take place to increase storage in Llyn Celyn and conversely some releases may be made from Llyn Celyn for recreational or power generation purposes. When the flow at Manley Hall decreases towards 10 m³/s, additional flow is released from Bala Lake. If that is insufficient, flow from Llyn Celyn is used to maintain 10 cubic metres per second (860,000 m/d) at Manley Hall. In extreme situations where the flow from Llyn Celyn is insufficient to maintain the flow, releases of water from Llyn Brenig are made. Circumstances can arise where even this is insufficient to maintain flows and in such cases drought provisions are agreed which progressively reduce the maintained flow at Manley Hall. The overall effect of this regulation has a marked impact on the
399:), a new 81,000,000-cubic-metre capacity regulating reservoir within the Bala Lake catchment area. This was completed in 1965 by Liverpool Corporation, and designed to operate in conjunction with the Bala Lake Scheme. This enables additional Dee abstractions of 327,000 cubic metres per day (3.78 m/s) together with additional flood control storage. In summer time the impact was to increase threefold the dry-weather flow for most of the length of the river. This development was hugely controversial at the time and
575:(DEEPOL 1) is issued to all participants. As contamination levels increase or the contaminant plug nears an abstraction point the DEEPOL level rises to DEEPOL 2 and finally DEEPOL 3 at which time the affected abstractions are closed until the river quality returns to normal. This quality management system was developed following a severe
492:
By 2002 the authorised abstractions had been taken over by three statutory undertakings and
British Waterways Board with a total licensed abstraction of 850,000 cubic metres per day (190,000,000 imp gal/d). In addition a residual flow of at least 364,000 cubic metres per day is maintained
126:
would be without water, unless local rivers such as the Mersey were rehabilitated. However, the natural flow of the River Dee during most summers is insufficient to sustain any significant abstractions. To overcome this problem, a series of reservoirs have been constructed to store the excess water
233:
and the Dee
Steering Committee to accurately predict when any release of pollutant would reach any of the main abstraction points on the river. The principle model flow data was provided from long-term data sets from Manley Hall gauging station which lies just upstream of the long, almost flat,
291:), which is only a short distance from the lake exit. This provided 18 million cubic metres of stored water in Bala Lake that could be controlled and used on a seasonal basis for low-flow regulation. This enables continuous abstraction from the River Dee of 235,000 cubic metres per day by six
579:
pollution of the River Dee in the 1980s which resulted in contaminated water being supplied to large areas of
Liverpool and the Wirral. Contamination of raw water is a more significant problem on the River Dee because the River Dee is normally of exceptionally good quality and as a result the
238:. With the benefit of frequent data updates and with the addition of data from real incidents together with real-time data from Manley Hall, it has become possible to predict arrival times of pollutants at any one point downstream of Manley Hall within a window of a few minutes at low flows.
574:
service. The results of the analysis are made available to the four participating organisations on a routine daily basis. For each of the critical water quality parameters alert levels and action levels have been set based on past experience. If an alert level is exceeded an immediate alert
569:
The River Dee regulation system also manages a water quality monitoring and alerting system that includes real-time quality monitoring for a wide range of chemical parameters supplemented by daily fixed site monitoring with analysis provided in near real-time by a dedicated
246:
In the late 1950s the Bala Lake Scheme was promoted to increase the available water for abstraction in the River Dee. Telford's original sluices were by-passed and the natural lake outlet was lowered. New sluice gates were constructed downstream of the confluence with the
415:
in order to supply
England with water. This caused a great deal of controversy, resentment and protest. To try to offset some of the environmental concerns associated with the scheme, some of the stored water was specifically set aside to make special releases to help
208:
In the industrial revolution many rivers in industrial areas became too polluted by effluents to be usable for water supply. The Dee however remained clean with relatively few polluting effluents in the Dee catchment upstream of
Chester. Consequently, the City of
479:). This reservoir was first filled in 1979 providing an additional 60 million cubic metres (49,000 acre⋅ft) of storage. This increased the potential for abstraction from the river in the lower reaches to nearly 900,000 cubic metres per day (200
220:
A project to review the pressures and opportunities for the Dee abstractions was undertaken and published in 1996. One of the outcomes of this report was the development and implementation of the River Dee Water
Protection Zone.
234:
serpentine section of the river path. The transit time through this stretch of the river can take several days in low-flow conditions. Additional data was obtained from gauges below the major reservoirs and from the sluices at
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The operating rules for the current system are agreed with all the participants and define the circumstances in which flow will be precisely managed. The key measuring location is at
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was established on the River Dee in 1999 as a mechanism to further safeguard the quality of the river. Although the statutory order was promoted by the
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In order to better manage flow and the substantial abstractions of water from the river, a mathematical model was developed by the
754:
P. E. O’Connell; G. P. Brunsdon; D. W. Reed; P. G. Whitehead. "Case
Studies in Real-Time Hydrological Forecasting From the UK".
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694:
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501:, safeguarding the passage of migratory fish and limiting the ingress of saline water over Chester Weir during high tides.
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Further statutory powers were gained in 1973 to construct another major regulating reservoir in the River Brenig valley -
292:
561:
of the River Dee. In dry years the hydrograph flat-lines at 10 m³/s whilst dry weather continues such as in 1990
613:
355:
As demand for water increased it was necessary to increase the storage on the River Dee and the next development was
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to control the flow downstream so that there was always sufficient water to supply the canal where it started at
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managed by a consortium of the three largest water companies licensed to take water from the river,
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114:, England, and then returning to Wales in a man-made channel constructed to gain land from the
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available in the winter time and release it back into the River Dee during the drier months.
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427:
A four megawatt hydro-electric station at the dam was also included in the scheme in 1965.
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it was supported and endorsed by the representative members of the Dee
Regulation Scheme.
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at the beginning of the nineteenth century in order to guarantee a supply of water to the
8:
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The River Dee has also been used for direct drinking water supply with the
118:. The Dee is the largest relatively clean river left near to the North West
580:
abstractions have been constructed directly from the river rather than via
494:
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as is more common when taking water from Rivers of less reliable quality.
299:. An additional benefit was a reduction in flooding events downstream of
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and twelve farms. Local people saw this a destruction of part of the
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403:, since the construction of the reservoir involved flooding the
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is a system of flow balancing and quality management along the
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far exceed the locally available sources of clean water. The
554:
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has been able to directly abstract Dee water since the first
731:
The Rivers
Handbook: Hydrological and Ecological Principles
712:
RIVER DEE - WATER RESOURCES STRATEGY. Consultation
Document
347:) was able to contain the worst of the winter flood peaks.
758:. Water Science and Technology Library. pp. 195–240.
729:
Calow, Peter P.; Petts, Geoffrey E., eds. (June 2009).
424:) and to disperse pollution events should they occur.
886:
663:. Regulated Rivers: Research & Management.
728:
796:"The Dee Regulation Scheme in a Nutshell"
935:River regulation in Conwy County Borough
587:
658:
401:remains politically fraught to this day
122:and without water from the Dee much of
965:Water supply and sanitation in England
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970:Water supply and sanitation in Wales
777:Snowdonia National Park - Llyn Tegid
756:River Flow Modelling and Forecasting
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878:Manley Hall Time series data -1990
692:Dee Valley Water - Water resources
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14:
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940:River regulation in Denbighshire
733:. Wiley-Blackwell. p. 223.
201:), built in the 1920s to supply
90:The water demands of North West
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674:The River Dee Regulation Scheme
497:in all but the most testing of
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950:River regulation in Snowdonia
859:. National River Flow Archive
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16:Water management scheme in UK
857:"67015 - Dee at Manley Hall"
718:. National Rivers Authority.
582:bank-side storage reservoirs
293:statutory water undertakings
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960:River regulation in England
955:River regulation in Wrexham
945:River regulation in Gwynedd
915:Llanrhaeadr-yng-Nghinmeirch
764:10.1007/978-94-009-4536-4_8
661:Regulation of the River Dee
641:GPX (secondary coordinates)
544:Manley Hall Gauging Station
10:
986:
553:), a gauging station near
215:Chester Waterworks Company
636:GPX (primary coordinates)
611:Map all coordinates using
130:This is the principle of
619:Download coordinates as:
838:Operation of the Scheme
803:Natural Resources Wales
489: imp gal/d).
297:British Waterways Board
241:
231:University of Lancaster
142:. Telford constructed
110:before flowing through
80:Natural Resources Wales
782:6 October 2011 at the
631:GPX (all coordinates)
594:Water Protection Zone
588:Water Protection Zone
60:Dee regulation scheme
817:"Dee at Manley Hall"
697:27 July 2011 at the
407:and the village of
217:was formed in 1826.
659:Lambert, A (2006).
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134:. This was used by
132:low-flow regulation
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598:Environment Agency
565:Quality management
282:Bala outlet sluice
271:52.9071°N 3.5835°W
76:Severn Trent Water
843:4 August 2012 at
819:. River Levels UK
740:978-1-444-31386-4
679:4 August 2012 at
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146:at the outlet of
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431:Llyn Brenig
409:Capel Celyn
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120:conurbation
116:Dee Estuary
108:North Wales
72:Welsh Water
49:Dee estuary
41: /
889:Categories
604:References
592:The first
572:laboratory
559:hydrograph
542: (
520:52°57′58″N
468: (
446:53°04′59″N
390:Llyn Celyn
388: (
366:52°57′00″N
357:Llyn Celyn
351:Llyn Celyn
336: (
314:52°53′31″N
280: (
258:52°54′26″N
225:Flow model
203:Birkenhead
192:Llyn Alwen
190: (
168:53°03′47″N
100:the Wirral
94:including
47: (
25:53°16′34″N
910:Llangywer
523:2°58′16″W
449:3°31′59″W
418:fisheries
369:3°41′35″W
317:3°37′05″W
305:Bala Lake
261:3°35′01″W
236:Bala Lake
171:3°33′36″W
148:Bala Lake
124:Liverpool
104:River Dee
96:Liverpool
64:River Dee
28:3°08′49″W
925:Llanycil
841:Archived
780:Archived
695:Archived
677:Archived
499:droughts
863:19 June
823:19 June
211:Chester
144:sluices
112:Chester
92:England
737:
577:Phenol
799:(PDF)
716:(PDF)
555:Chirk
493:over
865:2020
825:2020
735:ISBN
301:Bala
295:and
242:Bala
98:and
74:and
58:The
760:doi
626:KML
303:as
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481:×
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