{"id":87051,"date":"2022-08-03T14:45:31","date_gmt":"2022-08-03T14:45:31","guid":{"rendered":"https:\/\/www.bgs.ac.uk\/?p=87051"},"modified":"2024-02-28T09:19:57","modified_gmt":"2024-02-28T09:19:57","slug":"river-erosion-the-forgotten-hazard-of-flooding","status":"publish","type":"post","link":"https:\/\/www.bgs.ac.uk\/news\/river-erosion-the-forgotten-hazard-of-flooding\/","title":{"rendered":"River erosion: the forgotten hazard of flooding"},"content":{"rendered":"\n
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When considering natural hazards in a riverine or catchment setting, it is often high-magnitude flood events that grab the headlines.\u00a0In comparison, associated catchment hazards such as river scour are often overlooked, but these events can be no less costly in their societal and economic impacts.\u00a0Recent studies have shown that, in the UK, river erosion and associated impacts exacerbate flood damage by \u00a3336\u00a0million a year and are a considerable source of water pollutants, costing \u00a3238\u00a0million a year to remediate.River erosion further increases the costs of water treatment and maintenance of drainage networks by \u00a3132\u00a0million a year and accounts for 25\u00a0per\u00a0cent of valid\u00a0subsidence insurance claims (Li et al., 2021; Pritchard et al., 2013). <\/p>\n\n\n\n

Infrastructure damage<\/h2>\n\n\n\n

Scour causes physical modification to riverbeds and banks via the removal of sediment or engineered materials. It occurs when the forces imposed by the flow of water on a sediment particle exceed the stabilising forces (Kirby et al., 2015).  This is an environmental process occurring in response to the natural variability of river stream \ufb02ows and sediment regimes but, unlike hazards associated with flood waters that will eventually recede, the changes that result from river erosion can be permanent.This makes river scour extremely damaging when it intersects assets such as farmland, infrastructure, residences, historic sites, etc.<\/p>\n\n\n\n

Of particular concern is the significant damage river scour can cause to infrastructure adjacent to rivers, such as bridges, flood defences and electricity pylons. The Climate Change Committee\u2019s recent, independent assessment of UK climate risk has highlighted that the risk to bridges and pipelines from future erosion requires further investigation.<\/p>\n\n\n\n

Currently, river scour risk to UK railway bridges is estimated to cause the loss of 8.2 million passenger journeys each year, with an accompanying economic cost of up to \u00a360 million (Lamb et al., 2019). In 2009, flood events in Cumbria caused a tragic fatality and the partial or total destruction of 20 road bridges, costing the local economy an estimated \u00a32 million per week during the recovery period (Pizarro et al., 2020). <\/p>\n\n\n\n

Events such as these serve as a stark and increasingly frequent reminder of the destructive effects of river scour. As a result, the ability to predict where river scour is likely to occur across the UK river network is being recognised as increasingly important, both under current conditions and future climate change scenarios. The UK Government Environment Act (2021) has a target to reduce the impact of physical modification on the water environment and, between 2009 and 2015, \u00a368 million was spent towards reaching this goal (UK Government, 2021). <\/p>\n\n\n\t\t\t\t

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An example of river bank scour undermining a bridge in Cumbria. \u00a9 Copyright Karl and Ali<\/a> and licensed for reuse under the Creative Commons Licence.<\/p>\n<\/div>\n\t\t\t\t\t\n\t\t\t\t<\/figcaption><\/figure><\/div>

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Protective measures installed to reinforce river bank against threat of erosion to road infrastructure in Scotland. \u00a9 Copyright Roger Whittleston<\/a> and licensed for reuse under the Creative Commons Licence.<\/p>\n<\/div>\n\t\t\t\t\t\n\t\t\t\t<\/figcaption><\/figure><\/div>

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An example of road infrastructure threatened by river bank scour in County Durham. \u00a9 Copyright Trevor Littlewood<\/a> and licensed for reuse under the Creative Commons Licence.<\/p>\n<\/div>\n\t\t\t\t\t\n\t\t\t\t<\/figcaption><\/figure><\/div>\t\t\t\t<\/div>\n\t\t\t\t\n\n\n

Maintaining catchment health<\/h2>\n\n\n\n

Management and mitigation against river erosion is required at multiple scales and concerns a variety of stakeholders. Organisations involved in the maintenance of catchment health include:<\/p>\n\n\n\n