Distinguishing the Relative Importance of Environmental Data Underpinning flow Pressure assessment (DRIED-UP)

This project, funded by the Environment Agency’s EMCAR programme, has examined various sources of uncertainty in the relationship between LIFE score (a flow-sensitive index of the macroinvertebrate community1) and historical river flow, with the aim of optimising monitoring investment. The focus has been on alternative derivations of the river flow and LIFE data (gauged vs modelled river flows; taxonomy at species, genus or family level), and on the potential benefit of using local habitat data to improve understanding of LIFE-flow relationships. The project used data already collected by the Agency, and throughout, a strong emphasis has been on the adequacy of the relationships for water resources purposes. The study has focused on a limited number of lowland sites in Northern Anglian Region, which have minor artificial influences to flows, and for which excellent quality flow and biology data are available. New RHS surveys were undertaken for most of the sites. The main analysis tool was linear regression modelling within a multilevel framework, which provides a powerful analysis tool when data are hierarchically structured (e.g. repeated observations at a set of sites). This allows the integrated analysis of the effects of sample-level (i.e. flow) and site-level (i.e. habitat) variables together.