Towards a harmonized approach for hydromorphological assessment of rivers in Europe: a qualitative comparison of three survey methods

Abstract

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

Environmental assessment of the hydraulic structures by various artificialization parameters

“…A method which characterizes the morphology of river flows and determines the quality of aquatic habitats are becoming increasingly important in the decision-making process in the planning process for environmental protection, especially as a component of the assessment of environmental impact [4].…”

“…By definition, the river flows unchanged physical structure, or a great hydromorphological status, if they have good water quality, aquatic habitat supporting excellent ecological status [4].…”

Assessment of river hydromorphological quality for restoration purposes: an example of the application of RHQ method to a Polish Carpathian river

“…20,000 sites; Szoszkiewicz et al 2006) and 26 river types distinguished in the country. This seriously reduces reliability of establishing reference conditions (defined by the conditions at the 20% of highest ranked sites; Raven et al 2002) and, consequently, also of calibration of hydromorphological conditions at particular sites against type-specific reference conditions.…”

“…The RHS method also uses habitat quality as one of the components in defining reference conditions for a particular river type. Highquality (reference) hydromorphological conditions are here associated with the sites in which the low degree of anthropogenic modification allows them to be classified as near-natural and the habitat quality score falls within the 20% highest ranked sites (Raven et al 2002).…”

“…Consequently, a number of assessment methods were developed in particular countries to enable systematic evaluation of river hydromorphological quality (Rinaldi et al 2013a). Attempts at the standardization of these procedures brought about reviews (Belletti et al 2015) and comparisons of the methods used in different countries (Raven et al 2002;Scheifhacken et al 2012), and the European Committee for Standardization published two standards with the nomenclature and framework for hydromorphological evaluation of rivers (Boon et al 2010). However, many of the applied methods have one or more limitations: (1) they had been developed before the introduction of the Water Framework Directive and even though they provided the basis for its hydromorphological guidelines, they are not fully adjusted to its regulations; (2) they consist in static inventory of river habitat features and as such do not allow recognition of the ongoing hydrological and geomorphological processes; (3) they are general and involve little or no field surveys.…”