Flood Risk Assessment
Did you know that a flood risk assessment is now a design and planning consideration for small and large scale developments? ORS environmental engineers are experts on flood risk assessments, site surveys and flood modelling. Talk to the flood specialists for a free initial consultation.
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Flood risk assessments (FRA) are now a design and planning consideration for small and large scale developments.
Flood planning policy is set out in “The Planning System and Flood Risk Management – Guidelines for Planning Authorities 2009”. The policy aims to incorporate flood risk identification, assessment and management into the planning process thus avoiding unsuitable development in flood zones.
Flood zones and the flood compatibility of a development are used to describe the flood vulnerability of a development. A justification test needs to be passed on developments with low flood compatibility in areas where there is a high probability of flooding.
The predicted impacts of flooding were initially illustrated in Preliminary Flood Risk Assessment (PFRA) maps. Three hundred locations were then selected for Catchment Flood Risk Assessment and Management (CFRAM) studies and detailed flood maps have been developed for these locations.
Flood risk assessments (FRA) can vary in complexity and scale and are divided into 3 stages:
Stage 1 Flood risk identification – to identify whether there may be any flooding or surface water management issues related to the site and to give an early assessment to base further recommendations on.
Stage 2 Initial flood risk assessment
A Phase 2 assessment expands on the stage 1 assessment and includes;
- Appraisal of existing flood risk information.
- Qualitative review of flood risk posed to the site.
- Examination of the potential impacts the development will have on flooding elsewhere.
- Production of an Flood Risk Assessment Report including possible flood risk mitigation measures which would reduce flood risk to acceptable levels
Stage 3 Detailed flood risk assessment
A Level 3 assessment is a quantitative assessment of potential flood events. It is undertaken if the previous stages determine the need for quantitative analysis to assess flood risk issues relating to the development site and may include;
- Topographic survey of the river channel and surrounding ground levels/floodplains,
- Hydrological assessment of the subject catchment,
- Hydraulic calculations and modelling to quantify the flood risk to the site,
- Assessment of flood risk upstream and downstream,
- Review of existing and proposed surface water drainage and
- Recommend appropriate flood risk mitigation measures.
If you require a design phase FRA or need to respond to a ‘further Information’ request from a planning section, call and speak to one of our experts today.