Calibrated fluvial and coastal tools - Applications and limitations

Old, Gareth; Laize, Cedric; Nottage, Albert; Ramsbottom, David; Mountford, Owen. 2010 Calibrated fluvial and coastal tools - Applications and limitations. Environment Agency, 53pp. (CEH Project Number: C03429) (Unpublished)

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This report presents a step by step guide on how to use the Ecological Impact Assessment (EIA) tools for fluvial flooding (EIA F tool) and coastal inundation (EIA C tool). These tools have been developed within the Ecological Consequences of Flooding (ECF) project and may be used to support an environmental risk assessment (Old et al., 2010). When developing plans to manage flood risk, economic, social and environmental impacts are considered. There are many tools that help to estimate the economic impacts. However, there is currently no standard approach for evaluating the impacts on the natural environment within a flood risk assessment. Impacts of floods on the natural environment are often complex and include benefits and disbenefits. The Broad Scale Ecosystem Assessment (BSEA) toolkit is based on GIS data sets (existing or producible) that already exist or can be easily created and that have an apparent relationship with ecological characteristics. It is largely left to experts to interpret the ecological implications of these data. The GIS based tools presented here build on this work by introducing more scientific knowledge and objectivity to the assessment of ecological impact. The prototype tools will be used to provide an initial assessment of environmental assets at risk of fluvial flooding and coastal inundation. In this way it will help the authorities responsible for Flood and Coastal Risk Management to fulfil their duties under the EU Floods Directive, Habitats Directive, Bird’s Directive and Water Framework Directive. In the future it is envisioned that the tools will be embedded within software and made available to general users through an application like the Modelling Decision Support Framework that is currently in use by the Environment Agency. This will support Environmental Impact Assessments and Strategic Environmental Assessments for flood risk management activities. The prototype tools guide the user in making an objective and quantitative (where appropriate) assessment of the impacts of floods on the environment using ARC GIS 9.3 with its standard toolbox supplemented with Spatial Analyst. Although GIS based, they are spreadsheet tools that assesses the environmental impact of a given hydrological scenario by comparing this to the sensitivities of mapped environmental assets. The tools would support anyone undertaking an ecological flood risk assessment. They represent a tiered approach (comparable to the BSEA) to environmental impact assessment which is necessary to ensure that an appropriate level of analysis is adopted which is justified by the importance of the decision. Step by step guidance in using the tools is presented and supplemented with screenshots of the required GIS tasks. The environmental assessment is made using spreadsheet based scorecards. Ecological sensitivities to flooding/inundation are captured on the scorecards. The user must define the current flooding/relative sea level rise scenario and undertake a series of defined spatial data queries before assessing the impacts of flooding. The user must specify the impact assessment criteria as these are likely to change with time and with the specific objectives of a given assessment (e.g. what is an allowable loss of bird habitat?). The impacts of flooding are then evaluated by comparing the sensitivities of flooding to the flood characteristics. Given that the prototype tools use many spatial datasets of varying resolution, accuracy, age and completeness several areas of uncertainty must be acknowledged in any assessment and a decision must be made as to which need quantifying in a given study. The prototype tools have been tested in two fluvial and two coastal regions (see Technical Report). Test of both tools were successful and demonstrated the applicability of the tools. A degree of verification was presented by expert assessment of the results of the pilot tests. The limitations of both tools are considered and these mostly relate to knowledge on the sensitivities of environmental assets to flooding/inundation and the availability of data. The relevance of both tools to strategy and legislation is also considered. The method is currently ‘high level’, suitable for strategic planning but possibly not detailed enough for specific local decisions associated with flood risk management schemes and watercourse maintenance. Recommendations are made in the project Technical Report for moving towards a more detailed level of assessment.

Item Type: Publication - Report (UNSPECIFIED)
Programmes: CEH Topics & Objectives 2009 - 2012 > Water > WA Topic 3 - Science for Water Management > WA - 3.4 - Develop novel and improved methods to enable the sustainable management of freshwaters and wetlands
CEH Sections: Pywell
Funders/Sponsors: Environment Agency
Additional Keywords: flooding, habitats, fish, birds
NORA Subject Terms: Management
Ecology and Environment
Date made live: 04 Nov 2011 12:08 +0 (UTC)

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