Guidance on Best Practice for Marine and Coastal Physical Processes Baseline Survey and Monitoring Requirements to inform EIA of Major Development Projects.

Abstract

The purpose of this report is to provide guidance on marine, coastal and estuarine physical processes Environmental Impact Assessment (EIA) baseline survey and monitoring requirements for major development projects, namely: • Port and harbour developments; • Aggregate extraction; • Power stations (including nuclear); • Offshore wind; • Other renewable energy developments including: tidal range tidal stream wave • Sub-sea cables (especially where they make landfall). This has been achieved through a review of existing published guidance relevant to physical processes EIA studies, consideration of project examples (including both planned and operational developments) and from the experience gained by the authors during work on large scale marine developments. For the major developments identified above, pathways for change and potential impacts have been identified for each of the development stages (i.e. construction, operation and decommissioning). An attempt has been made to (qualitatively) determine the potential magnitude of these changes, identifying for which development types and development stages they are likely to be greatest. This is provided as a guide only as site and scale specific consideration is required for each specific development. The report also sets out the likely data requirements for EIA baseline characterisation, under the following topics: • Hydrodynamics (waves, tidal currents and water levels); • Sediments, sediment transport and Geology; and • Topography/ morphology. The objectives for collecting the data are described and where possible, guidance is given with regards to the spatial and temporal coverage. A key aim here is to help determine the adequacy of existing survey information, data gaps and the requirement (or otherwise) and scope for new data. Since some new data is likely to be required for the major developments considered herein, guidance is provided with regards to good practice for baseline survey design. An overview of the main techniques which may be used to gather baseline information on marine, coastal and estuarine physical processes is set out, including an appraisal of the capabilities and limitations of each technique. Given the uncertainty which is often inherent with any prediction of future morphological change, monitoring is sometimes a necessary requirement for large infrastructure projects. Accordingly, good practice for monitoring is identified. This includes discussion to address the following: • What are the monitoring objectives/ hypotheses; • Which parameters should be investigated; • How should the parameters of interest be measured; • The time of year/ frequency with which the parameter will be measured; • The establishment of review periods providing the ability to stop or modify the monitoring exercise if the measurements suggest no change; • The identification of appropriate thresholds of change; and • Identification of remedial action.