Water Quality is Key to the Success of Cardiff Bay
Darren Hanson, YSI Hydrodata Ltd 2 Focal Point, Lacerta Court, Works Road, Letchworth, Hertfordshire, SG6 1FJ, UK Tel: +44 (0)1462 673581 • Fax: +44 (0)1462 673582 • Email:
europe@ysi.com • Web:
www.ysihydrodata.com
Water quality has been a central theme in a redevelopment project that began with the creation of the Cardiff Bay Development Corporation in April 1987. This article will examine the role
that water quality has played in the remarkable transformation that has taken place in Cardiff, Wales, and explain how monitoring technology has developed to the stage whereby any person, anywhere in the world, can view live water quality data at multiple locations in the Cardiff Bay via the YSI EcoNet web-based system.
Cardiff owes much of its history to the Industrial Revolution of the 1790's, which stimulated mining in the valleys of South Wales. By the 1880’s, Cardiff had transformed from one of the smallest towns in Wales to the largest and its port was handling more coal than any other port in the world.
On the eve of the First World War in 1913, coal exports reached their peak at over 13 million tonnes. However, following the Second World War, demand for coal declined and international markets were lost as other countries developed their own steel industries. Trade was increasingly lost to container ports and by the 1960’s coal exports had virtually ceased.
Peter Gough from the Environment Agency of England and Wales was a student in Cardiff University during the 1970's and remembers the poor state of the local rivers: "The Taff was as black as coal and incapable of supporting most aquatic life. At its worst, in the 19th century there were reports of livestock dying after drinking from the river."
By the early 1980’s Cardiff Bay had become a neglected wasteland of derelict docks and mudflats. Much of Cardiff's population suffered from social exclusion with above average levels of unemployment.
The regeneration of Cardiff Bay was undertaken to create a complementary mix of housing, open space, commerce, leisure and industrial development. The project also included the construction of a barrage across the mouth of the bay to create a 200-hectare freshwater lake, fed by the rivers Taff and Ely, which would link all of the proposed developments and provide both aesthetic and recreational benefits.
Environmental considerations were extremely important in the proposed redevelopment plan and water quality protection measures were defined in the Cardiff Bay Barrage Act 1993, which stipulated that water quality objectives shall have regard to: (i) the recreational or other purposes for which use of the water is permitted by the Development Corporation, and (ii) the needs of the fish in the water and of migratory fish passing to or from it.
Water quality was required to meet the relevant standard as specified by the National Rivers Authority (now the Environment Agency of England and Wales). This standard was the maintenance of a minimum dissolved oxygen (DO) level of 5mg/litre. Peter Gough explains: "When the construction of a barrage was first proposed, concerns were raised for the ecological recovery of the catchment. Cardiff Bay had a huge tidal exchange which resulted in significant pollutant dispersal and a barrage would clearly prevent that and represent a risk to water quality in the future impoundment.
"One of the main concerns was the potential effect of the Cardiff used to handle more coal than any other port in the world
barrage on migratory fish such as salmon and sea trout, which were starting the process of recolonisation in the 1980s. They are very sensitive to pollution and to low DO levels in particular. A range of mitigation measures were therefore built into the proposed development plan."
Construction of the barrage took place between 1994 and 2000 at a total cost of £220million, and in 2000 Cardiff Council took over from the Cardiff Bay Development Corporation and through the Cardiff Harbour Authority (CHA) established five main objectives:
1. Maintaining the best environmental standards 2. Improving access to and around the Bay 3. Developing water use
4. Increasing the quality and range of facilities
5. Liaising with communities, commercial businesses and other organisations
Environmental issues
The main issues of concern for the CHA are debris management, flood defence, migratory fish, algae, birds, groundwater levels, problematic species and of course water quality.
Prior to the creation of the barrage, debris (typically 1000 tonnes/annum), which was mostly derived from the two rivers that fed the bay, would have been washed into the Severn Estuary. However, CHA now employs booms to collect debris for transfer to controlled areas.
Flood control has also improved with the barrage. In the past, heavy rain in combination with heavy rivers and a Spring tide would have resulted in flooding. However, CHA is now able to closely monitor and control water levels in the bay with the barrier's sluice gates. For example, in 2001 a 1:57 year rainfall event resulted in a bay water level rise of just 20cm.
IET November / December 2011
www.envirotech-online.com
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