Wetland vulnerability in East Anglia: The range of validity of a generalized classification approach

Abstract

AbstractWetlands are under threat from a variety of human activities and in response to this various assessment schemes have been devised. A recent hydrological vulnerability assessment procedure has been advanced by Lloyd et al. (1993) for East Anglia, UK, which deals with hydrological threats to fens. The assessment starts with a desk study which classifies a wetland into a particular hydrological class, and from this general statements can be made with regard to the wetland's likely vulnerability to such activities as water abstraction and pollution. No type of desk study, however, will always be able to predict the hydrological consequences of an activity with certainty. Thus, if protection of the wetland is of high priority, Lloyd et al. (1993) propose further stages of investigation of increasing expense and difficulty, involving hydrological monitoring and modelling.The purpose of this article is to explore how much desk‐study classifications such as that of Lloyd et al. (1993) can reveal about wetland hydrological vulnerability, using East Anglian field investigation and hydrological monitoring evidence. Three sites in East Anglia have been examined over a 2 year period, and the water balance and hydrological processes, together with the hydrological vulnerability of each site, deduced. Comparing these data with the conclusions from the desk study indicates that the classification procedure was able generally to identify the vulnerability of wetlands correctly at the regional scale, but the detailed studies showed that local features, below the scale resolvable by the classification and desk‐study procedure, can easily lead to incorrect assessments.The results of the East Anglian field investigations suggest that although classification procedures are adequate for providing general conclusions about the vulnerability of wetlands in a given region, they cannot be relied upon to be correct for a specific site and ensure its protection against any given hydrological threat. In the case of the assessment of important wetland sites, there is therefore no substitute for detailed hydrological and geological investigations. Because of the importance of seasonal hydrological data for detailed investigations and vulnerability assessment, it is also recommended that hydrological monitoring at a single point on important wetland sites should start well before an impact is envisaged.