FloodSmart – Prepare now for tomorrow
October sees us 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 a lot of information to absorb. We will break down information and advice in our FloodSmart campaign over the coming weeks.
This bulletin is longer than other items we will share as we want to explain some of the fundamentals first.
Earlier this year, Rope Walk in Littlehampton flooded which was devastating for the residents and business owners affected. This area flooded due to a tidal surge that exceeded the standard of protection offered by the individually owned defences. Many areas in the UK experience flooding from high tides, especially when combined with storm surges from severe weather. Other areas in the district have also been affected by flooding over recent years.
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. Areas are often interconnected, which we term as ‘Catchments’. Catchments often share drainage infrastructure which means that impacts are not necessarily always observed at the point of origin.
Key factors that contribute to flooding are;
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 will 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.
There are many reasons that flooding occurs in our district and there is no ‘one size fits all’ solution. More often than not, an area is affected by multiple sources of flooding and requires technical experts to separate the various issues and investigate possible solutions.
We know that the subject of flooding is emotive and causes a lot of frustration and disruption, and we hope that the information we will share as part of FloodSmart will be helpful.