CNR-IRSA activities related to INHABIT

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River typology

Water Framework Directive aims at defining a reference framework for the achievement by 2015 of the ‘good’ status for European water bodies (lakes, rivers, groundwater and coastal waters). One of the first steps required by WFD is the classification of water bodies in ‘river types’. Types can be defined according to one of the two systems provided by the Directive itself (System A and System B). Physical (e.g. altitude, catchment size, etc.) and geological (main substrate features) parameters are considered for classification by both System A and B. Compared to System A, System B allows for a higher number of parameters to be used with potential better suitability for Italians and South European rivers in general.
More in detail, System A is based on a ‘regionalization’ based on Ecoregion maps defined by Illies (1978, WFD Annex III) and combined with the following parameters: geology, altitude and catchment size. All the parameters are grouped in fixed and predefined categories (for instance, for geology: siliceous, calcareous and organic). In general terms System A is considered to be too strict and not adequate for many European countries. Also, altitude classes suggested by System A don’t take into account longitudinal variations among different countries or within the same country. System B gives the possibility of adapting the typology according to local or regional features of rivers. Some parameters are indicated as mandatory and some others are optional, in both the cases there is the option of modifying the categories for every parameters. Optional parameters cover a wide range of physical and geographical features, such as hydrology, substrate, rainfall, temperature, etc. As opposed to System A the adoption of System B allows to define a typology in line with the actual ecosystem structure and functionality. Considering the potential advantages of a regional approach, as suggested by System A, an appealing option can be created by combining the two systems (A and B) by performing a regionalization, as first step, and defining subsequently a proper typology. Such a typology would be based on a higher number of parameters considered by System A and would include the possibility of fine-adjusting the parameters categories, as allowed by System B. For the application of the WFD to types definition the individuation of reference sites must follow.  Type specific reference sites selection is a key step for the assessment of the ecological status based on biological communities.