Hydrological monitoring for Slade Brook SSSI.

The RPS Hydrology team at Bristol (Severn House) is involved with various hydrological monitoring studies – a particularly interesting example being for Slade Brook and Stowe Quarry in Gloucestershire.

Slade Brook was recently designated a Site of Special Scientific Interest because it supports one of the UK’s best examples of an actively forming series of tufa dams.

The term ‘tufa’ is used to describe freshwater calcium carbonate deposits from ambient waters. The deposits precipitate under a cool water regime and are normally soft, crumbly and organically rich. The tufa formative processes are considered to be both inorganic and organic, with the deposits existing in several forms – which tend to be separated into those resulting from vertical and from horizontal movements of water. The predominant form of tufa in Slade Brook arises from vertical movements of water, resulting in a longitudinal series of dams and waterfalls across the channel (see image at top of article).

Hydrological assessments concluded that Stowe Quarry was situated within the Slade Brook catchment – and that a proposed quarry extension had the potential to impact upon the tufa dams. Due to the complex nature of the drainage system and the conditions required for tufa dam formation, it was considered that an extension of Stowe Quarry could only be permitted if quarrying works were carried out in an appropriate and carefully monitored way. Planning permission was granted for the extension subject to the quarry operator adhering to an agreed management methodology and also to undertaking a monitoring study on Slade Brook to establish the inter-relationship of hydrological conditions responsible for active tufa formation.

Monitoring of flow rates, temperatures, pH, specific conductivity and rainfall started in 2005, and will continue through the quarry extension to determine whether the long-term status quo in Slade Brook is being maintained. In addition, water samples are periodically collected and their ionic balance assessed, also with spot measurements of water quality and flow, and some hydrological data available from 2001 to 2003 (see image above).

The study, in addition to helping maintain the active formation of tufa dams in Slade Brook, offers great potential for furthering our understanding of tufa dams.

For more information please contact:
RPS Bristol (Severn House) – Planning & Development
T: +44 (0) 1454 284 450