Flooding in Chesham
Thousands of properties are at risk of being flooded. In fact, thirty-five percent of properties in Chesham are predicted to experience flooding in the next 100 years.
Chesham's increasing flood risk
Climate change predictions suggest that the situation will get worse rather than better and flood hazards will increase. In particular, it is predicted that winters will get wetter and that more of the winter rain will come as intense rainfall, which is more likely to overwhelm the capacity of the soil and of man-made drainage systems. Modelling by the Met Office predicts an increase of 29% in rainfall intensity in Chesham due to climate change, which could result in an increase of over 20% in flood depths.
Flooding in Chesham
Chalk streams in the Chilterns often dry up in the summer – this is because they are fed by groundwater that is held in the chalk bedrock. When it has rained for some time and groundwater levels are high, the groundwater emerges as springs that feed the chalk streams. During a year of prolonged rainfall, as happened in Chesham in 2000/1, groundwater levels become so high they reach the surface and also combine with rainfall running off the surface to flood properties. Groundwater flooding has affected properties in the Vale Road/Berkhampstead Road area.
Some flooding is caused by water flowing over the ground. This surface water flooding can affect all areas but is particularly apparent in steep areas like Hilltop or Fuller’s Hill, where it can be seen flowing down flow paths such as roads during heavy rainfall.
Parts of the town, such as Pednormead End and Waterside, are at risk not only from surface water flooding but also from river flooding (also known as fluvial flooding) from the River Chess and Vale Brook.
Click here to see flood risk areas in the town.
The impact of flooding
Flooding, in particular from surface water, can happen quite suddenly and lead to deep levels and fast flows of water, especially in steep and hilly areas. Floodwater can seriously damage property, roads and other infrastructure, as well as hugely disrupt daily life by cutting off transport and communication links.
There is a risk to human life too; just two feet of water can float your car and six inches of fast flowing water can knock you over. In addition, there are lots of slip and trip hazards beneath the water as well as the risk of electrocution.
Also, because floods disrupt normal drainage systems, floodwater can contain sewage and create a serious health hazard along with standing water and wet materials in the home. This creates mould and spreads bacteria and viruses that can cause illnesses, disease and trigger allergic reactions.
Being flooded creates a practical crisis. Damage to buildings and contents can cost thousands of pounds and cause homes and businesses to be uninhabitable for months or even years.
Flooding can also have a devastating emotional impact, which can last a lifetime. The loss of personal belongings, especially those that are irreplaceable, such as photographs, and the insecurity and upheaval of not being able to live in your home for a while can cause feelings of stress, sadness and anger.