FloodSmart – Prepare now for tomorrow
As autumn sets in and the risk of localised flooding rises, we are revisiting our FloodSmart campaign from last year to help residents stay prepared and protected.
We will be sharing information about flooding in our area, what people can do to prepare and what do if it happens to you. If you deem it necessary, you are encouraged to be prepared in advance.
We will be providing information on what to put in a 'grab bag', who to sign up to for flood alerts, insurance, information on sand bags and much more.
As you read on you will see that flooding and associated issues, is a complex topic and there is plenty information to absorb. We will break down information and advise in our features over the coming weeks.
This bulletin is longer than other items we will share as we want to explain some of the fundamentals first.
Flooding in recent years has had a considerable impact on both residents and local businesses across affected areas of our district.
Rope Walk in Littlehampton was flooded in 2024; this was due to a tidal surge that exceeded the level of protection provided by privately owned flood defences.
Across the UK, many communities are vulnerable to flooding from high tides, particularly when combined with storm surges during severe weather events. Several locations within the district have also experienced similar flooding incidents in recent years.
The flooding in Barnham, West Sussex in 2024 was caused by a combination of factors including heavy, intense rainfall - 45mm of rain in just seven hours on one occasion. This overwhelmed local watercourses such as the Aldingbourne and Barnham rifes, leading to rising river levels and surface water flooding and the saturated ground made repair work difficult and contributed to further flooding. Southern Water described the soil conditions as sinking sand, complicating efforts to fix damaged sewers.
Flash flooding occurs when intense rainfall overwhelms the drainage capacity of an area, leading to a situation where water cannot be dispersed as quickly as it is accumulating. It is not necessarily just the water falling directly onto an area that leads to flooding.
Flood-affected areas are often linked together in what we call 'catchments'. These catchments frequently share drainage systems, meaning the effects of flooding may be felt far from where the issue originally begins.
Key factors that contribute to flooding
Heavy rainfall (pluvial flooding) - intense and prolonged rainfall, often associated with storms, can overwhelm drainage systems and lead to surface water flooding.
River overflow (fluvial flooding) - this occurs when the capacity of the waterways (River, streams, etcetera) is exceeded. As Arun is a coastal district our waterways also interact with the tide. This limits the amount of water that can exit the system using gravity solutions at high tide.
Coastal flooding (sea flooding) - this occurs where coastal defences are overwhelmed or fail. There are numerous inputs that influence coastal flooding but typically they happen when storm surges occur with high tides.
Groundwater flooding - groundwater flooding is when water under the ground (the water table) rises to the surface. When this happens water cannot soak into the soil as the space is occupied by groundwater.
Climate change - changing weather patterns lead to more frequent and extreme weather events, including heavier rainfall, increasing the risk of flooding.
Sea level rise - sea levels are also rising which worsens the issues for coastal districts. Rising sea levels not only increase coastal flood risk but also limit the amount of water that can leave the catchments through gravity solutions.
Unmaintained drainage systems - blocked drainage systems can fail to manage the influx of water during heavy rains. This includes ditches and culverts that might be on your land. Find out more about owning a watercourse here: https://www.gov.uk/guidance/owning-a-watercourse
Soil saturation - if the ground is already saturated from previous rainfall or groundwater, additional rain can cause water to flow over the surface rather than being absorbed.
Physical features of an area (topography) - topography plays a vital role in all sources of flood risk. The features of the land can cause water to flow rapidly into valleys and low-lying areas. In some instances, these areas may be lower than surrounding drainage infrastructure and even sea level, requiring water to be pumped away.
Land management - poor land management practices, such as deforestation and soil compaction, can reduce the land's ability to absorb water, increasing the chance of flooding.
Flooding in our district can arise from a variety of causes, and there is no universal solution that fits every situation. In many cases, multiple sources contribute to the problem, requiring technical specialists to disentangle the issues and explore appropriate remedies.
We understand that flooding is a deeply emotive issue that brings significant disruption and frustration. Through FloodSmart, we aim to share information that we hope will offer clarity and support.