The Planning System and Flood Risk Management - Offaly County ...

Step 1 - ScreeningScreening is the process for deciding whether a plan or project requires a FloodRisk Assessment (FRA).59In order to establish whether a flood-risk issue exists or may exist in the future,the following sources should be consulted.• Indicative flood maps produced by OPW;• National coastal protection strategy study flood and coastal erosion riskmaps;• Predictive and historic flood maps, such as those at http://www.opw.ie;• Catchment Flood Risk Assessment and Management Studies (CFRAMS);• Previous FRAs at national/regional, strategic and site-specific scales,including studies for flood-protection schemes;• Topographical maps, in particular digital elevation models produced byaerial survey or ground survey techniques;• Expert advice from OPW & Local Authorities who may be able to providereports containing the results of detailed modelling and flood-mappingstudies, including critical drainage areas, and information on historicflood events, including flooding from all sources;• Alluvial deposit maps of the Geological Survey of Ireland (which wouldallow the potential for the implementation of source control and infiltrationtechniques, groundwater and overland flood risk to be assessed). Thesemaps, whilst not providing full coverage, could be used to identify areas,where alluvium has been deposited, which have flooded in the recentgeological past, since that is the source of the alluvium;• Local libraries and newspaper reports;• Interviews with local people, local history/natural history societies etc.;• Walkover survey to assess potential sources of flooding, likely routes forflood waters and the site’s key features, including flood defences, andtheir condition;• National, regional and local spatial plans, such as the National spatialstrategy, regional planning guidelines, development plans and local areaplans provide key information on existing and potential future receptors.The predictive, indicative and historic flood event maps published by OPWor the coastal strategy maps being produced by DAFF are the key startingpoints. However, these only identify some of more obvious sources of floodrisk. Flooding from other sources such as surface water systems or adjoininghillsides are difficult to map, but need to be carefully considered. Techniqueshave been developed to allow for pre-screening of these risks using topographybased cell models.Planning Guidelines