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.