Assessment of the Hydromorphological Quality of Streams in the Venta River Basin District, Latvia

摘要: INTRODUCTION According to the EU Water Framework Directive (WFD), surface waters in Europe must achieve good ecological quality by 2015 (European Commission, 2000). The WFD requires assessment of running based on various biotic (phytoplankton, macrophytes, phytobenthos, benthic invertebrates, and fish fauna), chemical, hydromorphological elements When evaluating status water bodies, predominant role used be given (Logan Furse, 2002), with support hydromorphology physico-chemical Previous monitoring focused chemical parameters invertebrates (O'Hare et al., 2006), but new legislation states that it is necessary include status. Assessment river needed not only for implementation also nature conservation purposes, such as condition Special Areas Conservation under EC Habitats helping management restoration rivers (Boon 2010). Rivers have important functions ecosystems, natural flood control, refuge development, production, species conservation. However, aquatic ecosystems are among most severely affected habitats (Sala Streams their floodplains been modified a result land drainage, floodplain urbanization, defence (Sparks, 1995; Kronvang 2007). More recently, physical disturbances damming, channelization, separation channel floodplain, destruction riparian vegetation become more relevant therefore included into methods (Feld, 2004; Lorenz Timm 2011). morphology, longitudinal lateral connectivity, well discharge regime disturbed Central Europe. Only 10% reaches alpine region can classified near (Muhar In Latvia there still streams sites corresponding 'conditions representative group minimally sites, i.e. reference site, described selected physical, biological characteristics' (Springe There long history assessments systems far less developed (Erba 2006). Various indices 2000; Friberg 2005; Kamp 2007) different countries characterize quality. Characterization structure habitat gaining importance context environmental planning, appraisal, impact assessment. Hydromorphological plays crucial because determine 'undisturbed' 'heavily modified' conditions (Raven 2002). order fulfil demands WFD, stream changed fundamentally from single index system holistic approach 2004). Numerous researchers emphasize knowledge about hydrological regime, geological formation, geomorphological processes stream, impacts anthropogenic origin both past present (Riis Biggs, 2003; Tremp, Several European methodologies identify morphological character Jungwirth, 1998; Raven Buffagni Kemp, 2002; Rinaldi 2013). reason wide application these they rely well-established activities simple classification criteria (Bizzi Lerner, 2012). …