As a planner, architect, property investor, or property developer you’ll need to understand the potential risk of flooding when designing and developing a new site. You’ll also need to consider how your site may affect potential flooding elsewhere in the community – especially if it sits within a known flood zone.
Most importantly though, you’ll need to understand how you can use mitigation measures to manage these risks for all stakeholders involved. It is likely you will need to know and understand all of these aspects before you put in a planning application.
Whether for a residential or commercial site, a Flood Risk Assessment (FRA) identifies these risks and mitigation measures for you. The level of information to document in a Flood Risk Assessment should be specific to the nature of the proposed development.
Sources of flood risk
At the offset an indication of the potential flood risk to the site will be required. The purpose of this early work is to identify all sources of flood risk and determine whether any further work is required to understand any risks.
Site specific flood risk
A site specific appraisal provides an understanding of the particular risks of flooding the site.
Potential impacts to the development including what effects it may have elsewhere on flood risk are set out in a FRA report in accordance with NPPF guidance.
Flood Consequence Assessment
In Wales, a Flood Consequence Assessment (FCA) report is required for developments in flood zones C1 and C2. TAN15 requires the level of detail of the Flood Consequence Assessment to be proportionate to the scale and nature of any development.
The Welsh Flood Zones have been produced using our JBA flood model known as JFlow®. The model has been used to produce the 1% (1 in 100 year) and 0.1% (1 in 1000 year) flood outlines.
Meeting EA requirements
A detailed flood risk study can be provided if the Environment Agency require further quantitative analysis. This might be needed to assess detailed flood risk issues relating to the development site or its effects further downstream.
For example; Flood Modelling may be required to establish specific flood levels at a site where the Environment Agency do not hold this data.
Documents, such as the National Planning Policy Framework (NPPF) and Planning Practice Guidance (PPG), have been developed to assist you. Section 10 of the National Planning Practice Guidance (PPG) covers ‘Meeting the challenge of climate change, flooding and coastal change.’
It specifies, ‘Inappropriate development in areas at risk of flooding should be avoided by directing development away from areas at highest risk, but where development is necessary, making it safe without increasing flood risk elsewhere.’
Sustainable Drainage Systems (SuDS)
New developments have the potential to cause an increase in impermeable areas, an increase in surface water runoff rates and volumes, and a consequent increase in downstream flood risk due to overloading of sewers, watercourses, culverts and other drainage infrastructure. Managing surface water discharges from new developments is therefore crucial.
Strategic Flood Risk
We provide support to Local Planning Authorities (LPA’s) and Risk Management Authorities (RMA’s) to help them understand flood risk in their areas.
SFRA’s form an integral part of LPA’s evidence base, identifying appropriate locations for development and underpinning local flood risk management policies and strategies. SFRA’s assist planners and developers.
We can support you alongside FRA’s in many ways.
- Breach impact assessment
- Level-for-level floodplain compensation
- Flood map challenge
- Evacuation plans
- Options appraisal studies