The Habitats Directive and the Environment Agency’s Restoring Sustainable Abstraction programme (RSAp) have focused attention on a large number of wetland sites across the country. Some of these are large, high profile sites that have been subject to many detailed studies in the past. However, many sites have had little work carried out on them and the behaviour of their hydrological systems are poorly characterised.
ESI has been working with the Environment Agency, English Nature and a number of developers to improve the level of understanding of a wide variety of wetland sites and thus to define more accurately the degree to which they are being affected by current or proposed abstractions and other activities. Sites vary from coastal dune and slack systems, through Midlands mires and mosses to Lake District Basin and Valley Mires. Work has included a wide range of field investigation techniques (drilling, augering, installation of piezometers, field mapping, borehole and surface geophysics) as well as desk studies and detailed hydrological and hydrogeological modelling. Over the last few years we have been working increasingly closely with aquatic ecology experts to define the hydrological conditions that determine the ecological health of wetlands and river reaches. We are also working with other specialists to find new, more appropriate ways of modelling river systems.
Our flexible and collaborative approach and our ability to work closely with scientists of different disciplines has been particularly important in achieving a consensus on the way forward for these sites. Key sites are discussed below.
Thorne and Hatfield Moors are large areas of raised mire which are nationally and internationally significant wetland habitats. Groundwater abstraction from the underlying Sherwood Sandstone aquifer, local gravel extraction and milling of peat in the moors may all affect the groundwater regime of the moors and this may be having a long term impact on the moors’ ecology. ESI collated and interpreted the available hydrogeological data and prepared a detailed report on the interaction between the peat and underlying units on behalf of the Environment Agency.
30 Wetlands in Midlands Region. Over the past two years, the Environment Agency Midlands Region has commissioned ESI to identify any effects of consented abstractions or discharges on 30 SSSI wetland sites across the Region. Each site required the collation of all the available data and the development of a conceptual model of the hydrological and hydrogeological processes at the site. This allowed the significance of any nearby abstractions and discharges to be identified. The reports also make recommendations on further work necessary to characterise the hydrological and hydrogeological regime at the sites more fully. For the largest site assessed (Fenns and Whixhall Moss) the assessment was carried through to Stage 3 and included a variety of field investigations.
19 Basin Mires in Cumbria. The Environment Agency, in collaboration with English Nature, wished to review the vulnerability of 19 Basin and Valley Mire sites located in Cumbria to surface and groundwater factors. This required a preliminary desk study and collation and presentation of all relevant information for each site in a standardised format. The reviews were designed to be updated by the user as further information becomes available from fieldwork or research. ESI using a GIS based approach to collate and present all relevant data together with a preliminary conceptual model of each site.
Quarry Impact Assessment. The Cornelly Group of Quarries is made up of three quarries with planning permissions which are subject to review under the provisions of the Environment Act 1995 (ROMP). The Environment Act submissions were called in by the National Assembly for Wales (NAW) for determination in 1999 largely due to the perceived risks to nearby sand dune cSAC (Kenfig and Merthyr Mawr Dunes). Tarmac Western Ltd appointed ESI to carry out a hydrogeological investigation and impact assessment for the quarries. The work involved field investigations, monitoring, analysis and preparation of the Environmental Statement. Developing a conceptual understanding of the behaviour of groundwater in the dune systems and the links from this to the key aspects of nature conservation interest was particularly important.
Ritton Woods Hydrological Studies. In 2002 English Nature were considering plans to carry out forestry work at Ritton Woods in south Shropshire as part of the ‘Back to Purple’ campaign to re-establish heather across much of the Stiperstones area. Given the nature of the site, English Nature felt that it was important that a comprehensive assessment of any potential hydrological impacts was made prior to any work being carried out. English Nature therefore commissioned ESI to review historical patterns of run-off and recharge for the area and calculate changes that may occur with the proposed deforestation. Potential drainage issues were also thoroughly examined and remedial works proposed as necessary.
School development, East Midlands. An outline planning application was submitted to develop a 6-Form school on land adjacent to a Local Nature Reserve with SSSI status. The SSSI is partly dependent on the hydrological regime for its nature conservation interest. The Environment Agency and English Nature objected to the planning application and requested that a more detailed hydrological/hydrogeological impact assessment be carried out. The investigation included the installation of piezometers, field tests to determine the hydraulic properties of the underlying minor aquifer, groundwater and surface water sampling, and weekly monitoring of groundwater levels and surface water levels in the SSSI. Potential impacts associated with the planned development were identified and measures to mitigate these potential impacts were proposed.