Table 3. Overview of the main presures and measures to mitigate flood defence impacts, related to pressures and mitigation measures in the CIS reporting guidance 2016. Pressure Pressures in WFD reporting guidance 2016 Hydromorphological alteration Ecological impact Mitigation measures options Relevant KTM in WFD reporting guidance 2016 Transversal works Dams for floods attenuation, Retention 4.2.2 Dams, barriers and locks -Flood protection Loss of longitudinal continuity in sediments, water and biota; alteration of hydrological regime if multiple uses Loss of sediment/ biological continuity - interference with fish population movements; alteration of flow regime and river morphology fish passages downstream sediment by-pass actions e-flows 5 Improving longitudinal continuity (e.g. fish passes, by-pass channels) 7 Improvements in flow regime and/or establishment of ecological flows Transversal works Retention Check Dams 4.2.2 Dams, barriers and locks -Flood protection Loss of longitudinal continuity in sediments, water and biota; alteration of hydrological regime if multiple uses Impairment to sediment flux/loss of biological continuity - interference with fish population movements; alteration of flow regime and river morphology fish passages openings (filtering action) for sediments E-flows 5 Improving longitudinal continuity (e.g. fish passes, by-pass channels) 7 Improvements in flow regime and/or establishment of ecological flows Transversal works Grade control structures 4.2.2 Dams, barriers and locks -Flood protection Loss of longitudinal continuity in biota (sometimes in sediments, depending on the geometry and topographic characteristics of the reach upstream) Loss of sediment/ biological continuity - interference with fish population movements fish passages 5 Improving longitudinal continuity (e.g. fish passes, by-pass channels) Lateral works Bank 4.1.1 Physical alteration of area/shore – Flood Protection Loss of lateral continuity (connectivity with floodplain/hillslopes) Loss of riparian zone / marginal habitat / loss of lateral connectivity / loss of sediment input replacement of hard structures with soft engineering ones; creation of natural-like irregularities 6 Improving hydromorphological conditions of water bodies other than longitudinal continuity
Lateral works Embankments 4.1.1 Physical alteration of area/shore – Flood Protection Loss of lateral continuity (connectivity with floodplain/hillslopes) Loss of riparian zone / marginal habitat / loss of lateral connectivity / loss of sediment input creation of natural-like irregularities; set-back embankments 6 Improving hydromorphological conditions of water bodies other than longitudinal continuity Lateral works Groynes 4.1.1 Physical alteration of area/shore – Flood Protection Loss of lateral continuity (connectivity with floodplain/hillslopes) Loss of riparian zone / marginal habitat / loss of lateral connectivity / loss of sediment input creation of natural-like irregularities; increase of roughness trough wood/rocks 6 Improving hydromorphological conditions of water bodies other than longitudinal continuity Complex works Flood detention basins 4.1.1 Physical alteration of area/shore – Flood Protection Loss or reduction of lateral and longitudinal continuity of sediments, water and biota Loss of riparian zone / marginal habitat / loss of lateral connectivity / loss of sediment input creation of natural-like diversity within the flood detention basin 6 Improving hydromorphological conditions of water bodies other than longitudinal continuity Complex works Flood Deviation channels 3,7 Abstraction or flow diversion - Other Temporary Loss of lateral and longitudinal continuity of sediments, water and biota temporary Loss of riparian zone / marginal habitat / loss of lateral connectivity / loss of sediment input no real measure as impacts are temporary
Complex works Flood Drainage systems (pipes, intakes, ditches, etc.) Alteration of hydrological regime Alterations of water inputs through artificial means storage tanks at the delivery to attenuate discharge peaking Complex works Channel straightening (including meander cut-offs) 4.1.1 Physical alteration of area/shore – Flood Protection 4,4 alteration - Physical loss of whole or part of the water body Alteration of hydrodynamic and morphodynamic characteristics Loss of morphological diversity and habitat Irregular shaping of the banks to favour morhological diversity and habitat etherogeneity 6 Improving hydromorphological conditions of water bodies other than longitudinal continuity Complex works Channel revetment 4.1.1 Physical alteration of area/shore – Flood Protection 4,4 alteration - Physical loss of whole or part of the water body Loss or reduction of lateral and vertical continuity of sediments, water and biota; loss of natural substrate Loss of riparian zone / marginal habitat / loss of lateral and vertical connectivity / loss of sediment input increase of roughness elements (cobbles or boulders) 6 Improving hydromorphological conditions of water bodies other than longitudinal continuity