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ABSTRACT1. Characterizing the physical structure and assessing the habitat quality of rivers is becoming more important in the context of environmental planning, appraisal and impact assessment. In Europe the EC Water Framework Directive requires assessment of hydromorphological quality in establishing the ecological status of rivers.2. Hydromorphological quality assessment plays a crucial role in the Directive because it is used to determine 'undisturbed' and 'heavily modified' conditions of rivers. A common approach is needed to ensure comparability of classification outputs between EU Member States.3. Three hydromorphological and river habitat assessment methods, developed in Germany, France and the UK, were used for qualitative cross-comparison in 2001. Each was tested on river stretches in North-East France and in the French Pyr! e en! e ees.4. The type of features recorded by all three methods was broadly similar, but differences in survey strategy, data collection, and analysis resulted in variations in quality assessment. Different interpretation of what constitutes 'undisturbed conditions' has a major impact on outputs. There are also scale-related problems in comparing the different methods.5. Despite these differences, there is sufficient common ground to allow refinement of the methods and achieve better harmonization. This will require technical agreement on the terminology and definition of features, and a reach-based hierarchical framework for survey and reporting.6. An impact-based assessment centred on deviation from undisturbed hydromorphological conditions could be the best option for a simple, practicable classification scheme, but agreement is needed on the criteria used to define and calibrate such a system.7. Habitat quality assessment using the presence and diversity of features as a basis for classification needs to be improved. Assumptions used for diagnostic interpretation need to be tested

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ABSTRACT1. Over the last 20 years the concept of 'freshwater quality' has expanded to incorporate a range of physical, chemical, hydromorphological and biological characteristics. In Europe, this process has been given greater impetus by the EC Water Framework Directive (WFD) and the requirement for Member States to assess and monitor a comprehensive suite of freshwater features.2. Assessments of river hydromorphology are needed not only for implementing the WFD but also for nature conservation purposes, such as monitoring the condition of Special Areas of Conservation under the EC Habitats Directive and helping in the management and restoration of rivers. At present there are few detailed methods available in Europe for assessing river hydromorphology, and standard approaches are urgently required.3. The European Committee for Standardization (CEN) works to promote voluntary technical harmonization in Europe in conjunction with worldwide bodies and its European partners. The production of a CEN standard for assessing the hydromorphological features of rivers began in September 1999 and culminated in the production of EN 14614 in November 2004.4. EN 14614 is a 'guidance standard' that provides a framework of general principles and sets out which aspects of river hydromorphology should be assessed, how to plan and conduct field surveys, how results should be interpreted and presented, and ways of applying quality assurance procedures. 5. A second CEN standard on river hydromorphology has recently been published. Using simple scoring systems, this will enable the extent of hydromorphological modification to river channels, banks, riparian zones and floodplains to be recorded and assessed consistently.6. CEN standards encourage European collaboration and provide a framework which other countries can use to develop their own assessment methods. However, ways need to be found to streamline the process of standardization and to ensure that published standards influence the work of researchers, environmental regulators and policy makers.

ABSTRACT1. Some ecological effects of physically modifying rivers are still unclear, partly due to scale factors, but also because the character of high quality habitat is poorly understood.2. Surveys at 278 sites on 141 near-natural streams and rivers in northern and western Europe were carried out between 1994 and 2009 to benchmark the habitat quality assessment system used for River Habitat Survey (RHS).3. The objectives were to establish if RHS was suitable outside the UK, investigate if 500 m was still valid as the survey length, suggest a benchmarking strategy and recommend improvements to habitat quality assessment protocols.4. Some modifications to RHS are needed to take account of differences in hydrological conditions, land-use and, most importantly, riparian habitat structure found in mainland Europe.5. On average, 82-87% of channel attributes and 87-98% of channel and bank features were recorded within the first of consecutive RHS sites, confirming that 500 m is an effective sample length for characterizing small rivers.6. Stream-flow character appeared to influence the distribution of several in-channel features, with greater diversity and between-site variation associated with rivers of mixed flow-types. To account for local variation and for effective use of survey time, it is recommended that two or more consecutive RHS sites are used for benchmarking purposes.7. A suite of assessment protocols with agreed criteria and analytical rules, linked to specific objectives (e.g. nature conservation, geomorphic condition), is needed to establish the character and habitat quality of rivers in a consistent fashion.8. A multi-discipline benchmarking programme using hydro-ecological regions in Europe would build on existing knowledge and help to improve both the inter-calibration and local application of quality assessment protocols. Data-sharing by hydrologists, river ecologists and fluvial geomorphologists would improve the basis for managing rivers in support of the European Water Framework Directive and Habitats Directive.

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