Geographical Association

The Environment Agency is producing Catchment Flood Management Plans. This is a planning document developed with other key decision-makers in the river catchment. It sets the strategic direction for managing the catchment for the next 50 to 100 years taking account of climate change.

The Environment Agency has investigated a number of detailed options for managing flood risk in Uckfield. This has to take into account land use, the hydrology of the River Uck, and likely future flooding. Most importantly, it has to listen to the views of local residents and businesses. This process is called Flood Risk Management.

Although the options offer different standards of protection, they can be compared because the costs and damages are calculated over a 100-year period.

Option 1

If the Environment Agency does nothing, nature will take its course. There will be £0 cost, but damages of £21,974,000.

Option 2

If the Environment Agency does the minimum, it will cost £631,000, but with damages of £13,580,000. All the other choices need to be compared with this.

This option would involve building:

• A flood wall around the edge of the Somerfield car park. In a flood event the wall would divert flow coming across the northern floodplain and car park back into the river, hence avoiding flooding in the High Street. At the design flow, the river will run bank full downstream of the High Street.


• A raised entrance to the car park as part of the flood defence with a flood gate or ramp over the wall to enable disabled and trolley access. The supermarket owners prefer a flood gate as it is easier for customers but a flood gate is only effective if it is closed. Those managing the flood defences prefer a ramp as it physically prevents water flowing through the defence.


• In the 1 in 25 year flood, six residential and 74 commercial properties are at risk from flooding. Option 3 would cost nearly £16,500 per property to implement.

• This option would involve building high floodwalls by the mill, around the edge of the supermarket car park, by the houses on the edge of the flood plain and along the north bank downstream of the High Street Bridge. Walls would vary in height from 0.4m to 2.2m.


• This option would channel the floodwater through the town until it reaches the large channel downstream. In a larger than design flood, the enlarged channel capacity will continue to function, so only the extra water would flood the town.


• In the 1 in 100 year flood approximately 18 residential and 102 commercial properties are at risk from flooding. Option 4 would cost £57,000 per property.

• This option would increase the capacity of the channel upstream of the bridge all the way along the fish bypass channel. A fan shape dug into the northern floodplain would direct flows into the widened channel. A low level floodwall around the supermarket car park (Option 3) is also needed to make best use of the capacity of the existing channels. If the design capacity of the enlarged channel is exceeded, only the extra water will flood the town so this scheme would still be effective in a larger flood.


• Building with an additional culvert would also increase the capacity of the High Street Bridge.


• The capacity of the channel downstream of the High Street Bridge would be increased by 30 to 40m3/s. About ten buildings on the Industrial Estate would need to be demolished to clear the additional land needed for the larger channel.


• In the 1 in 200 year flood approximately 18 residential and 102 commercial properties are at risk from flooding. Option 5 would cost £190,000 per property.

• This option would involve building a flood storage reservoir upstream of Uckfield. This would hold back floodwaters, and so reduce the maximum flood flow through Uckfield. This option also needs the low wall around the supermarket car park (Option 3) to be built, to maximise the amount of water that can flow down the river channel before the town starts to flood.


• A flood storage reservoir remains effective so long as it does not become full of water. If a larger flood occurs, the reservoir fills up and the extra will flow over the top of the reservoir through a specially strengthened channel. When this occurs, the benefits of the flood storage reservoir largely disappear. The result may be almost as severe flooding as would occur without the storage.


• In the 1 in 200 year flood approximately 18 residential and 102 commercial properties are at risk from flooding. Option 6 would cost £55,000 per property.


• Approximately 50% of flow through Uckfield comes from tributaries, and not from the River Uck through Buxted. Upstream storage will therefore only control half of the flow through Uckfield.

The Environment Agency gathers together all the information before making a decision. To reach a decision it balances the benefits and costs of each scheme.