A crucial stage of the Water Framework Directive 2000/60, and the characterization of reference conditions in rivers, is typology which is described inAnnex II. There two systems of classification for rivers (System A and B) are recommended.
System A is based upon 25 preassigned ecoregions according to the distribution of animals’ communities in the European surface waters. For each ecoregion types are specified obligatorily by using the altitude (3 categories), the size of catchment area (4 categories) and geology (3 categories).
System B uses the obligatory descriptors of System A but it replaces the ecoregions with geographic coordinates. It alsot allows the use of optional descriptors and other alternative parameters. Τhe use of the obligatory and optional descriptors are expressed in the Geographical Information System, concluding in a number of surface water body types.
System B is considered more flexible in comparison with System A. That’s because it allows the selection of the appropriate physical abiotic characteristics, in each country. But according to WFD (Annex II) if system B is used, Member States must achieve at least the same degree of differentiation as would be achieved using System A. Accordingly, the surface water bodies within the river basin district shall be differentiated into types using the values for the obligatory descriptors and optional descriptors, or combinations of descriptors, as are required to ensure that type specific biological reference conditions can be reliably derived.
In Greece for the typology of a catchment area is used system B, because the river Axios belongs to two ecoregions (6 and 7). In Northern and Central Greece is used system B’ only when comparison of stations is needed upstream/downstream a point source of pollution (Lazaridou et al. 2014). This system consists of altitude, which is categorized according to Dikau (1989)-with a modification in the 3rd category from Kemitzoglou (2006)-, catchment size according to the Intercalibration Exercise of the Mediterranean Rivers (RM), by Van de Bund et al.(2004 -4 categories), geology which is categorized into calcareous and siliceous (organic is not present in Greece), and slope which is categorized according to Demek (1972)- with a modification of grouping the 6 categories to 3 according to Kemitzoglou (2006).
Demek, J. (1972). Manual of detailed geomorphological mapping. Academia, Prague, pp. 344.
Dikau, R. (1989). The application of a digital relief model to landform analysis. Taylor and Francis, London, pp. 51-77.
Illies J. (1978). Limnofauna Europea. Gustav Fisher Verlag, Stuttgard, New York, pp. 532.
Kemitzoglou D. (2006). “Type characterisation of river ecosystems in North and Central Greece”. Postgraduate Thesis, Department of Biology, A.U.TH.
Lazaridou M., Kanli L, Ntislidou Ch. & Albanakis K., (2014.) Comparison of river typology systems in Northern and Central Greece. European Water: 42 (3-18).
Van de Bund, W., Cardoso, A. C., Heiskanen, A.S., Nõges, P. 2004. Common Implementation Strategy for the Water Framework Directive (2000/60/EC). Overview of Common Intercalibration types. Final version 5.1. Ecological Status Working Group 2.A.
Kanli Lamprini (2009) Comparison of river typological systems in Greece, Postgraduate Thesis, Department of Biology, AUTH Thessaloniki.
