What Causes Flooding in Reading and Caversham?
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How can we reduce flooding in north Reading and Lower Caversham? What causes flooding in Reading and Caversham? 1947 flooding Major floods, on the scale of 1947 are very rare… history shows they do happen, and could happen again. Photograph source unknown North Reading and Lower Caversham have flooded many times in recent years. In 2012 and 2014, low lying areas of Caversham flooded, causing internal flooding to residential and commercial properties in the area. You may also remember the flooding in 2003, where many houses were surrounded by floodwater and a number of roads, including Napier Road, Amersham Road, Paddock Road, Send Road and Piggots Lane were closed, some for as long as 5 days. The Environment Agency maintains rivers and streams and operates weirs and locks in and around Reading and Caversham. This work reduces flood risk from smaller, more regular floods, but more significant flooding cannot be reduced by watercourse maintenance alone. The best scientific evidence suggests that severe weather events are likely to be more frequent and more intense in future, increasing the risk of flooding across the United Kingdom. We are investigating how we can reduce the impact from a major river flood on a scale similar to 1947. A similar sized flood would cause major disruption to the local economy, access routes and residents at large. It would create road blockages, transport disruptions and could cause water damage to homes and businesses. We take climate change projections into account in all modelling and planning work. Based on for the likelihood of more frequent flood events, we have identified a range of options which could reduce flooding in the north Reading and lower Caversham area. All options we are investigating reduce flooding from rivers, however surface water flooding is still a risk. There is still a significant amount of investigation required, we are sharing the options with you now to gain your views so we can take them into consideration when deciding which, if any, of the options we can take forward. How can we reduce flooding in north Reading and Lower Caversham? What have we done so far? What areas are at risk of flooding from the River Thames? To work out how we can reduce flooding we must first understand the flooding mechanisms in the Reading and Caversham area. The main risk of flooding in north Reading and Lower Caversham is from the River Thames. Due to the flat urban landscape of Reading flood water can remain for long periods of time. The flood map represents the existing flood risk from the River Thames. The dark blue shows areas that are likely to flood in a large flood, we have not recently experienced a flood of this size. The closest comparison is the flooding in 2003 which was smaller. The lighter blue shows the additional areas that would flood in a major flood, such as was experienced in 1947. Planning flood map Large flood Major flood Main river Environmental surveys and ground investigation We have completed surveys to help us understand the Ecology in the areas where we could develop a scheme to reduce flooding. These have included surveys to establish what species may be present in the areas the works may take place. You may have seen our contractors carrying out ground investigations using diggers or drilling rigs as shown in the photograph. We have to carry out this work early so we can find out what may or may not be possible. We are continuing our programme of surveys over the next few months. We will plan these to ensure there is as little disruption as possible. How can we reduce flooding in north Reading and Lower Caversham? A Flood Alleviation Scheme for north Reading and Lower Caversham? We have looked into a number of different ways to reduce flooding, the techniques here we have considered and may be used in combination with other techniques. On their own they only reduce flooding from smaller floods. For major floods they need to be used along side permanent measures such as flood walls and embankments. Diverting flow Property level resilience We have looked into whether Property level resilience involves making changes to individual diverting flood water through the properties to reduce the risk of floodwater entering homes and area would reduce flood risk. businesses. It can be used in combination with larger This is very difficult to achieve flood alleviation schemes to reduce flooding. due to the lack of space, without There are a number of property severely impacting existing level resilience products, including residential areas. flood doors, door barriers, Flood storage areas automatically closing airbricks, non- return valves and sump pumps to On its own there is not enough avoid or minimise water getting room to hold the amount of inside a property. The level of their water needed to reduce effectiveness would be limited here flooding from major events. because flood water can remain In combination with other high for a number of days. However techniques to reduce flooding they could still help to reduce this could be beneficial. severity of flooding, especially if used in combination with other methods Temporary barriers Due to the length of temporary barriers that would be needed to reduce flood risk in this area, it would not be practical to rely on these alone. Some areas are not possible to access to get barriers in place. In combination with other techniques temporary barriers could be beneficial. Example of Temporary Often prevention is the best Environment Agency members barriers being tested. strategy. setting up temporary barriers. How can we reduce flooding in north Reading and Lower Caversham? A Flood Alleviation Scheme for north Reading and Lower Caversham? Why isn’t dredging an alternative? Can natural flood management help? Dredging can be an important part of maintenance but is not These are processes that enhance the enough on its own to reduce flooding from a major flood. natural features of a river, to reduce flooding impact on a community. Methods The Environment Agency maintains rivers and streams and operates include slowing flow of water, improving weirs and locks. This work reduces flooding from smaller, more soil quality so more water is absorbed and regular floods, but more significant flooding cannot be reduced by creating more areas for water to be watercourse maintenance alone. stored. Dredging can be an important part of the Environment Agency’s general maintenance programme. We consider each location carefully and do it where we know it will make a difference. Understanding where dredging will and won’t reduce flooding is essential. We must be sure it will reduce flooding to local homes and businesses and won’t increase flood risk downstream. Dredging the River Thames would not significantly reduce flood risk in this area. In many cases, dredging isn’t the best long-term solution because rivers can quickly silt-up again. It can even increase flood risk. Studies have indicated the River Thames itself is self-regulating. Dredging can be costly, disruptive and environmentally damaging, These techniques can help reduce and would require frequent re-dredging as the natural tendency of all flooding from minor floods in some areas. rivers after dredging is to deposit silt and return to their more natural In this area they would not help reduce dimensions. flooding from major floods. Flood walls and embankments Embankments are raised lengths of land which will be grassed to give them a natural look. Flood walls can be made of different materials depending on where they are. Where possible we would design a flood wall to blend in with the surrounding area. All options that we are considering involve a combination of permanent flood walls and embankments. The photo gives and example of what a flood wall can look like. Photo courtesy of the Environment Agency How can we reduce flooding in north Reading and Lower Caversham? Options to reduce flooding in north Reading and Lower Caversham An overview of the options we have been considering and would like your views on… We have been investigating options to reduce flooding from the River Thames in the Lower Caversham and north Reading area. All proposals shown here are in the early stages of design and may change as a result of feedback from this engagement and new information that arises as we develop a design. We would like your views on which option you think we should take forward. We are running a consultation which we hope you are able to respond to. We will use the feedback in combination with technical information when deciding which option we can Option 1, Nire road to Christchurch playing develop. fields All options include building flood walls and embankments. The difference between the options is in the length of the flood walls and embankments. Option 1 is the shortest, option 2 is an extension of option 1 and includes some temporary defences, option 3 is the same as option 2 with the addition of further embankment and walls to the south of the River Thames.. Option 4, not shown on a diagram here, is to do no new work, but continue with our existing work which includes maintaining rivers and streams and operating weirs and locks. As we increase the length of the flood walls and embankments Option 2 – Nire Road to Promenade Road we increase the area that would benefit from reduced flood risk from the River Thames. However, we also find that the cost of building the scheme increases and we would need to secure extra funding to be able to deliver these.