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Regional Environmental Assessment of Potential Impacts on Benthic Ecology from Cumulative Marine Aggregate Dredging, South Coast, UK Joni Backstrom, Dafydd.

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Presentation on theme: "Regional Environmental Assessment of Potential Impacts on Benthic Ecology from Cumulative Marine Aggregate Dredging, South Coast, UK Joni Backstrom, Dafydd."— Presentation transcript:

1 Regional Environmental Assessment of Potential Impacts on Benthic Ecology from Cumulative Marine Aggregate Dredging, South Coast, UK Joni Backstrom, Dafydd Lloyd-Jones, Paul English and Nigel Thomas Presented by Justine Saunders Emu Limited Biarritz, October, 2011

2 Presentation Outline Why are marine aggregates important in the UK? Marine Aggregates Regional Environmental Assessment (MAREA) Study Area - Coastal, Geological, Oceanographic and Ecological Characterisation Assessment methodology Results - Direct Effects (seabed removal) Results - Indirect Effects (suspended plume) Summary Findings and Recommendations

3 Why are marine aggregates important in the UK? Concrete for the construction of homes, schools, hospitals, infrastructure Declining land-based sources in the region with substantial environmental impacts Proximity to markets – e.g. London Olympics 2012 South coast of England - 33 % of demand for aggregates from marine sources Replenishment of beaches and coastal protection Exports - foreign demand for aggregates If such demand for construction and coastal defence is to be met, it is vital to ensure continuity of marine supply

4 Overview of the Physical Effects of Marine Aggregate Dredging Conceptualisation of various (trailer suction hopper) dredging activities and their physical effects on the environment

5 The South Coast Marine Aggregates Regional Environmental Assessment (MAREA) Companies will independently progress an EIA to obtain development licences Good knowledge of local, site-specific impacts; less awareness of other existing and potential developments Decision to undertake a voluntary Regional EA to support the renewal of existing licences and new licences MAREA allows increased awareness and assessment of the regional environmental context of a development (cumulative and in- combination effects) – high-level screening and scoping of issues Other REAs located around the Thames, Humber and East Coast South coast region is made up of : 13 existing production areas 3 prospecting areas 8 application areas Max tonnage ~ 16 x 10 6 /year

6 South Coast - Characteristics Wide range of coastal types Hard rocky cliffs Soft erodible cliffs Cobble beaches Sandy beaches Estuaries Isle of Wight Bournemouth Southampton Swanage Portsmouth

7 Seabed Habitats Insert Biotope map with some underwater images Sublittoral mixed sediment Sublittoral coarse sediment Rocky outcrops Sublittoral sand

8 Modelling of Plume Footprint Plume footprint based on site-specific reference flows, water depth, spring tide current speed and rate of overflow discharge: Predicted maximum development scenario suspended sediment plume footprints and concentrations Spring Flood tide Spring Ebb Tide Tidal flow simulation: TELEMAC (LNH EDF)

9 Matrix-based approach - GIS based analysis of regional cumulative impacts (effect-receptor overlap) Effects, receptors, magnitudes, sensitivity and impact significance agreed between industry and regulators Multiregion REAs across the UK MAREA cumulative impact significance - methodology

10 Results – Assessment of seabed removal West of the Isle of Wight - effects non-significant as the biotopes and habitats here are widespread throughout the region and have high recoverability East of the Isle of Wight - effects are of minor significance in the as the biotopes underlying the habitat types here are more sensitive, e.g. SS.SMx.CMx.OphMx (associated with brittlestar beds) and SS.SCS.CCS (circalittoral coarse sediments – includes seahorses and Sabellaria) Owers - effects are of minor significance, sensitive biotopes include SS.SSa.CFiSa (circa- and infralittoral sands with characteristic species) and SS.SSa.CMuSa (seahorses present)

11 Results – Assessment of suspended sediment plume West of the Isle of Wight - effects non-significant as the biotopes and habitats here are widespread throughout the region East of the Isle of Wight - effects are of minor significance in the as the biotopes underlying the habitat types here are more sensitive, e.g. SS.SMx.CMx.OphMx (associated with brittlestar beds) and SS.SCS.CCS (circalittoral coarse sediments – includes seahorses and Sabellaria) Owers - effects are of minor significance, sensitive biotopes include SS.SSa.CFiSa

12 Main Findings and Recommendations From a regional perspective, non-significant impacts on Benthic Ecology from seabed extraction and suspended sediment plume due to aggregate activities; Some sub-regional impacts of minor significance due to presence of sensitive biotopes; Such sensitive biotopes identified and to be assessed at EIA level Other topics covered included effects on sites of nature conservation, birds, marine mammals, fish and other socio-economic activities High level of precaution adopted in terms of the magnitude of dredging and plume footprint REA methodology has proved an effective tool for assessing cumulative effects from marine aggregate extraction and in-combination effects across a range of activities (e.g. commercial fishing) at a regional level Levels of significance of impact agreed by regulators thereby providing a high-level screening and scoping exercise that can streamline individual EIAs Methodology being adopted by offshore windfarms in the UK – ZAP – Zone Appraisal and Planning – effects of wind farms at a regional level

13 Thank-you for listening South Coast Dredging Association (SCDA) The Crown Estate HR Wallingford (modelling) Contact: Acknowledgments

14 A bedrock platform with a veneer of superficial sediment. Variable morphology A rough, irregular bedrock surface with sediments lying in small basins. Three main N-S trending palaeochannel complexes incised into bedrock. May be completely or partially infilled with a range of sediment types Major NE to SW trending Northern Palaeovalley Dominant regional morphology


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