Quantifying sediment pathways in anthropogenic floodplains during extreme flooding

英国最近的特大洪水对城市和农村社区造成了广泛和昂贵的影响。大部分费用来自水中沉积物造成的财产损失。例如，2015/16年冬季极端洪水（风暴德斯蒙德，伊娃和弗兰克）造成的总经济损失的最佳估计在13亿至19亿英镑之间，其中包括3.08亿至3.92亿英镑的住宅财产损失（环境署，2018年1月）。沉积物在洪泛平原上的积累是一个自然过程，但在与人类活动交叉的地方，会造成昂贵的清理费用和对作物和财产的损害。更好地管理泥沙泛滥是政府制定基于集水区的解决方案和自然洪水管理政策的一个关键目标。同样，农业政策和最佳做法越来越多地寻求将土壤保持在土地上，以帮助减少非现场损害，这种损害通常远远超过雨水造成的侵蚀的现场影响。为了支持这些政策，目前正在进行修订，与英国离开欧盟的决定，需要更好地了解沉积的沉积物是在上游产生的，以具有成本效益的方式有针对性的干预措施，以及沉积物是如何沉积在复杂的人为改造的洪泛区。这一建议将首次将洪泛区复杂性的新措施与沉积物来源、数量和形态的可靠估计结合起来，联合收割机。我们将探讨如何洪泛区的发展和基础设施与农业城市景观的影响，其中流动沉积物通过集水区在极端洪水是由洪泛区处理的过程。我们将利用最近受到严重影响的塞文河和怀伊河流域的实地考察点，与利益相关者组织合作生成新的数据。这些新数据将用于开发新的理论和证据，以支持英国更大的低地洪泛区未来的洪水和侵蚀风险管理。

Recent extreme floods in the UK have created extensive and expensive impacts on urban and rural communities. Much of the costs result from property damage caused by sediment in the water. Here, for example, the best estimate of total economic damages resulting from extreme flooding in the winter of 2015/16 (storms Desmond, Eva and Frank) ranges between £1.3-1.9 billion, including £308-392M for damage to residential properties (Environment Agency, January 2018). Accumulation of sediment on floodplains is a natural process but creates expensive clean up and damage to crops and property where it intersects with human activities. To better manage sediment laden flooding is a key aim of government policy for catchment-based solutions and natural flood management. Similarly, agricultural policy and best practice are increasingly seeking to keep soil on the land to help reduce off-site damage which typically far outweighs the on-site impacts of rain-driven erosion. To support these policies, which are currently undergoing revision in connection with the decision of the UK to depart the EU, requires improved understanding of where the deposited sediment is generated upstream for targeting interventions in a cost-effective manner, and how that sediment is deposited in complex human-modified floodplains. This proposal will for the first time, combine novel measures of floodplain complexity with robust estimates of sediment source, quantity and morphology. We will explore how floodplain development and infrastructure associated with farming to urban landscapes influence the processes by which mobilised sediment passing down the catchment in extreme floods is processed by the floodplains. We will use field sites in the recently heavily impacted River Severn and River Wye catchments, to generate new data in collaboration with stakeholder organisations. This new data will be used to develop new theory and evidence to support future flood and erosion risk management on the larger lowland floodplains in the UK.