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The Impact of Heavy Rainfall on Culverts and the Environment

For many people, culverts are usually things that they don’t think about or pay much attention to as they are mostly out of sight. However, they serve a very important purpose and they greatly contribute to the developed world. Culverts are essentially tunnels or channels that direct and convey water beneath public roads, trails, railways, and embankments. They serve as an important way of keeping water flowing while keeping public roads and pathways clear and dry. Culverts need to be engineered following particular regulations and they can also be constructed using a variety of materials, such as steel, aluminium, concrete, and polyethene.


Heavy Precipitation Events

One of the main reasons why culverts are gaining increased attention now more than ever is due to climate change and the subsequent increases in the amount of rainfall. Across the country, we’ve seen that the occurrences of heavy precipitation have significantly increased over the last twenty years. When there is heavy rainfall, large volumes of water can fill up the existing drainage systems quickly and this often leads to overwhelmed culverts.

In this case, when a culvert is overwhelmed and cannot effectively convey the amount of water that is trying to flow through it, the water usually ends up being backed up on the upstream side. This can cause serious localised flooding which may lead to several millions of pounds worth of damage. In other situations, the backed-up water may overflow across public roadways and cause significant disruption to transportation, not to mention further increasing erosion damage to the culverts. When there is an upstream failure, sediment and debris blockages may also cause failures downstream. This can lead to flooding on farmland, property, and other roads. However, it’s not just large-scale flooding that can cause damage, even smaller-scale flooding at undersized culverts can seriously degrade the water quality, block habitat access for aquatic life, erode the stream banks, and also damage private and municipal property.

In order to prevent these problems and keep the drainage systems operating smoothly, it’s vital that regular inspections and maintenance are carried out on culverts across the country, particularly smaller culverts that are too small for the volume of water that flows through them. Across the country, there are thousands of culverts and they come in different sizes and serve different purposes, but it’s important that they are all maintained. The local authorities and water authorities may also need data to help them identify the most important culverts that need addressing or replacing.


An Abundance of Historical Climate Data

In the UK, we have a wealth of historical data on the climate and climate records are important resources for engineers so that they can choose the most appropriate diameters for culverts in different locations. Culverts should not be too small as environmental damage and disruptions could occur if there is frequent flooding. On the other side, culverts should also not be too large as the cost of installing culverts significantly increases which would inflate the cost to complete other projects.

Taking a statistical and methodical approach to calculating the suitable diameters for culverts often involves analysing extreme rainfall data. By analysing this precipitation data, estimates for the recurrence interval of heavy precipitation can be calculated. This information is very useful and the Environment Agency will be able to assess the climatological risk of certain culverts failing. It also means that they can weigh up the environmental, economic, and societal impacts versus the advantages of installing new culverts.


What about the Future?

The future is unfortunately quite unpredictable when using and analysing past data, given the increased frequency of extreme rainfall events in the UK. This means that using data from the past may no longer be an adequate guide for future precipitation events. An example of this is that some culverts that may have been of a suitable size that when they were installed years ago, may not be prone to damage and flooding from heavy precipitation. This then brings a dilemma to the local authorities and water authorities. Should they still rely on past data which may not provide an adequate estimation of what the conditions may be years into the future? Or, should they be considering installing larger culverts now, which are oversized by our current standards, in order to accommodate for future extreme precipitation events?


New Tools & Updated Information

The Environment Agency is aware of this dilemma and they are working on solving this problem. In addition, the global climate model projects provide indications for future heavy precipitation events and how the current trend may be in the future. At RWB Group UK, we use online tools that are based on hydrological models that account for land use. The topography will be able to inform users about the current volume of runoff expected under various conditions.

These specialised tools enable stakeholders to come up with their own predictions and scenarios for the future whilst incorporating changes in characteristics. These characteristics may be enhanced retention or increased development in order to help choose the most suitable sized culverts for different locations. They can also choose the most important culverts to repair or replace first. These are all specialities of RWB Group UK.

Hopefully, this article has helped you to understand the significant environmental impact that culverts have and why they are now the big focus for many research projects. Not only are construction companies and civil engineers focusing on this topic, but also their legislators, biologists, zoologists, and environmentalists. Culverts are not just “pipes and tunnels”, they are in fact much more than that.


Contact RWB Group UK for Culvert Cleaning

With the UK recording higher levels of rainfall, maintaining culverts and making sure that preventative maintenance is in place is now more important than ever. Reducing the environmental impact of blocked or damaged culverts helps to prevent flooding and other potential risks to public roads, railways, and trails.

RWB Group UK is a registered waste carrier with OHSAS and ISO accreditations and we provide culvert cleaning and inspection services across the UK.

Get in touch with our culvert engineers on 0800 488 0658 or you can get a quote here.