Glasgow City Council: Bespoke Flood Risk Assessment and Design Requirements

It has now been two years since the adoption of the National Planning Framework 4 (NPF4) — the spatial strategy for Scotland which replaced NPF3 and the Scottish Planning Policy (SPP).

When it comes to flood risk, NPF4 should generally be compatible with the requirements set out in the local development plan for the corresponding local authority. Even though the NPF4 is set on a national level, Local Development Plans and their associated guidance documents are considered alongside the NPF4 to inform planning decisions. Some councils have requirements related to flood risk, which go beyond the requirements set out in the NPF4.

However, there are still some unique flood risk criteria in place in areas across Scotland, including Glasgow City Council.

Glasgow’s Unique Development Pressures

Glasgow City is the council region with the largest population, as per the latest data from 2023. Glasgow City is a dynamic and rapidly changing place, which attracts a large number of international and domestic students, choosing to settle and start their career in the City of Glasgow. It is no surprise that the consequences of this trend in terms of planning are increased demand for housing, student accommodation and pressure to put industrial land to good use.

Bespoke FRA Requirements

Glasgow City Council’s SG8 Water Environment Guidance published in 2017 (and still adhered to) outlines the needs for properties to be assessed against flood events with certain return periods, based on the nature of the development.

Generally, across Scotland, residential developments which have habitable dwellings, flats or sleeping accommodation at ground level do not need to be assessed up to the 1 in 500 + Climate Change flood extents, and are generally assessed against the Flood Risk Area (i.e. the 1 in 200 year plus climate change event). This is a bespoke Glasgow criteria.

SEPA’s flood maps have been prepared on a strategic level, and do not include these bespoke flood risk extents such as the flood risk extents for 1 in 500y+CC and 1 in 1000y+CC fluvial flood events.

Therefore, it is important to remember that if your development includes overnight accommodation with habitable dwellings at ground floor level, or a development which the council consider as “Strategic Infrastructure”, you will likely need bespoke hydraulic modelling to assess against the 1 in 500y+CC or 1 in 1000y+CC fluvial flood event. This can also have an impact on your proposed finished floor levels, which generally need to be set a minimum of 600mm above the design flood level.

It is also worth remembering that Glasgow City Council require an independent check of any FRA or DIA before submission.