1D Flood Risk Assessments

Flood Risk Assessments are carried out taking cognisance of ‘The Planning System and Flood Risk Management (DoEHLG, 2008).  These projects utilise SuDS (Sustainable Urban Drainage Systems) and GDSDS (Greater Dublin Strategic Drainage Strategy) techniques in stormwater management and drainage network design.  River surveys are performed to assess route capacities and predict flood levels using ISIS modelling software from which design levels such as finished floor can be computed.  Envirologic uses Trimble R4 VRS surveying technique for collection of coordinates and elevation data in all field investigations.  The scale of work involved in any given Flood Risk Assessment is dependent upon the scale of the development for which they are being performed. 

Envirologic have recently invested in a Hydrolite Plus Single Frequency Echosounder.  This is mounted onto a kayak along with an RTK receiver.  This gives river bed elevations to Malin Head datum, with a vertical and horizontal accuracy of 30 mm. 

 

Learn more about how we apply this to our projects below

Projects

  • Flood risk assessment for this whiskey distillery involved surveying of 35 river cross sections, extending to the coastal outfall downstream of Ardara. The 1D model was validated against CFRAM findings using site-specific flow gauging. Buildings were proposed in Flood Zone A and therefore required significant level for level compensation storage along with satisfying the Justification Test.

  • Envirologic designed a flood alleviation scheme to facilitate a quarry extension and at the same time prevent a repeat of historical road flooding. The scheme included large attenuation ponds to manage catchment runoff, two road crossings and an assortment of drainage channels and pipelines. The scheme also required land acquisition and has been approved in principle by Galway County Council and OPW. The scheme also aided the granting of a discharge license.

  • Envirologic have been working for several years with Fingal County County studying wetlands on Howth Head. The first step was to carry out a comprehensive survey which identified 70 wetland sites. We then advised on measures to restore/enhance existing wetland habitats (e.g. Bog of Frogs). Works in 2024 will explore the feasibility of creating new wetlands. Fingal County Council view new wetland cells as being beneficial not alone for habitat creation but to serve as firebreaks and firefighting water supplies.