Ecohydrological methods for the investigation of significant damage at groundwater dependant terrestrial ecosystems

This paper aims to share the experiences of UK conservation and environment agencies of implementing Water Framework Directive investigations to determine significant damage at GWDTEs (Groundwater Dependent Terrestrial Ecosystems). Much of this work has been driven by various members of the ‘Wetlands Task Team’ of the Water Framework Directive UK Technical Advisory Group (WFD UKTAG). A three-tier approach to site investigation is described, providing suggestions for useful sources of information to inform both initial and detailed desk studies and subsequent site investigations. Both affordable and more expensive investigative methods are described; their usefulness in terms of contributing to a final site conceptual model are discussed. The need for long term monitoring to characterise baseline conditions and incorporate hydrological extremes (wet years and dry years) is demonstrated. A summary table provides a list of investigative methods scored on their cost, time required and contribution to conceptual understanding. The importance of both hydrogeologists and ecologists working together throughout the process is stressed and the ‘ecohydrological site walkover’ is proposed as a principal activity for any site investigation.