RHS Benchmarking in Europe.
RHS benchmark sites were originally surveyed across England, Wales, Scotland and Northern Ireland to identify sites of very high quality with little or no impact (i.e. the reference condition sites as defined in the Water Framework Directive). With the advent of the WFD and the development of a CEN standard for assessing hydromorphology, Benchmarking was extended to other European countries to include a wider diversity of sites and river types and enable comparison and cross calibration between eco-regions.