The Planning System and Flood Risk Management - Offaly County ...
The Planning System and Flood Risk Management - Offaly County ...
The Planning System and Flood Risk Management - Offaly County ...
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with the Water Framework Directive (WFD) River Basin <strong>Management</strong> Plans(RBMPs), will establish a prioritised set of flood risk management measuresfor their relevant areas, including the use of structural <strong>and</strong> non-structuralresponses as outlined above.152.35 <strong>Planning</strong> can have a significant role to play with respect to flood riskmanagement, in particular in avoiding or minimising future increases in floodrisk. <strong>The</strong> planning process therefore constitutes a parallel, but related <strong>and</strong>inter-dependent, process to that of flood risk management. As such, the twoprocesses should each have regard to the objectives, direction <strong>and</strong> constraintsof the other to ensure alignment between planning instruments, such asDevelopment Plans <strong>and</strong> the <strong>Flood</strong> <strong>Risk</strong> <strong>Management</strong> Plans (FRMPs).2.36 A major function performed by the floodplain <strong>and</strong> wetl<strong>and</strong>s is to hold excesswater until it can be released slowly back into a river system or seep into theground as a storm subsides. <strong>Flood</strong>plains have, therefore, a valuable functionboth in attenuating or storing floodwater <strong>and</strong> through their ability to conveyfloodwater in a relatively controlled <strong>and</strong> safe way. Areas of floodplain <strong>and</strong>wetl<strong>and</strong>s should, therefore, be recognised <strong>and</strong> preserved to the extent possibleas natural defences against flood risk. It is important to identify <strong>and</strong>, wherepossible, safeguard areas of floodplain against development in both urban<strong>and</strong> rural areas. By retaining open spaces for storage <strong>and</strong> conveyance offloodwater, flood risk to both upstream <strong>and</strong> downstream areas can be moreeffectively managed without reliance on flood defences. This is an importantelement of the now internationally accepted philosophy of “leaving space forwater”.Sustainable drainage systems2.37 Development of previously ‘green’, or permeable, l<strong>and</strong> within an urban area(such as gardens) increases the impermeable area. Rain falling on impervioussurfaces is usually directed into receiving watercourse through surface waterdrainage systems. Although such drainage systems are effective at transferringsurface water quickly, they provide only limited attenuation causing thevolume of water in the receiving watercourse to increase more rapidly <strong>and</strong>increasing flood risk. As a consequence sustainable drainage systems (SuDS)can play a role in reducing <strong>and</strong> managing run-off to surface water drainagesystems. In this context the Department is currently reviewing its document“Recommendations for Site development Works for Housing Areas” whichtraditionally was used to provide guidance on design st<strong>and</strong>ards for smallerdrainage systems. <strong>The</strong> aim of this review is to set out best practice in regardto the use of sustainable drainage systems in respect of surface water drainage.2.38 A small-scale yet practical example of a sustainable drainage system (SuDS)is the use of permeable pavements which can help to reduce run-off rates <strong>and</strong>flow volumes from parking areas as well as access roads. Permeable pavementsallow rain-water to infiltrate through the paved surface <strong>and</strong> into underlyinglayers <strong>and</strong> sometimes storage containers allowing gradual release of water<strong>Planning</strong> Guidelines