An allowance for rainfall intensities changing due to climate change should be incorporated into storage capacities.

In May 2022 the Government updated it’s 'Flood risk assessments; climate change allowances' document. This guidance provides updated climate change figures which should be used for flood risk assessments and drainage strategies to help minimise vulnerability and provide resilience to flooding and coastal change in the future. Within this is an update on the Peak Rainfall Intensity Allowance in small and urban catchments. The climate change allowance required is dependent upon the lifespan of the development after it has been completed. The LLFA take a conservative, risk adverse approach to flood and water management and therefore expect the Upper End figures to be used. Depending upon the catchment area, either a 40% or 45% climate change allowance should be used. Please refer to the below tables.

Table below showing the peak rainfall intensity allowance in small and urban catchments (Roding, Beam and Ingrebourne, Upper Lea, Cam and Ely Ouse)

	Total potential change anticipated for the ‘2050s’ (a lifetime up to 2060)	Total potential change anticipated for the ‘2070s’ (2061 to 2125)
Upper end allowance	40%	40%

Table below showing the peak rainfall intensity allowance in small and urban catchments (Combined Essex, South Essex)

	Total potential change anticipated for the ‘2050s’ (a lifetime up to 2060)	Total potential change anticipated for the ‘2070s’ (2061 to 2125)
Upper end allowance	45%	45%*

*Please note EA 'Exceptions' policy in relation to '2070s' epoch.