Impacts of Climate Change on Erosion, Sediment Transport and Soil Carbon in the UK and Europe

对于负责管理土地和水资源的政府机构和法定机构来说，过去十年已日益认识到一系列紧迫的环境问题，并认识到这些问题未来的发展轨迹存在重大的不确定性：在欧洲，水土流失是对土壤最严重的威胁（Kirkby et al., 2004）。此外，土壤侵蚀速率对地表径流的变化很敏感，但在不断变化的气候条件下，对未来侵蚀速率的空间明确预测尚不可用。2. 农业耕作对土壤的再分配是土壤性质和生产力空间变异性演变的关键影响因素（Quine and Zhang, 2002），因此对耕地土壤碳的排放和固存具有很强的控制作用（Van Oost et al., 2004,2005）。在不断变化的气候条件下，土壤有望成为碳循环反馈的重要控制因素（Cox et al., 2000）。然而，土壤侵蚀和再分配在碳循环中的作用仍然是一个有重大争议的领域，对与侵蚀相关的全球碳通量的估计从1 Gt/年的源到1 Gt/年的汇不等（Stallard, 1998; Lal, 2003）。3. 被侵蚀的泥沙向河道输送会造成许多环境问题，包括弥漫性污染、细泥沙及相关污染物的运输和储存、水生生态系统的退化，以及由于河道内和岸上沉积而导致的水流输送能力和洪水频率的变化（Walling等，1999,2001；Greig等，2005）。Defra和环境署目前面临着欧盟水框架指令（WFD）实施带来的重大挑战，以及解决上述问题的要求，以管理和维持所有地表水的生态状况。此外，这些问题造成的威胁在未来气候条件下的潜在变化还有待量化。在国家和区域尺度上解决这些挑战将需要发展新的建模方法，能够调查目前知之甚少的气候、水文、地貌和生物地球化学过程之间的反馈。这个项目将连接CEH和Met。由利兹大学和埃克塞特大学开发的区域气候和水文模型的办公室专业知识，为CEH建立一个坚实的战略平台，从这个平台上解决这一系列基本的科学和环境问题，这是EHFI计划的核心，也是CEH和NERC的核心任务。该项目将以最近的建模进展为基础，在以下领域开发新的模型：坡面水文与土壤侵蚀；2. 河流内泥沙运移、洪水输送和河漫滩沉积；3. 坡面土壤再分布与坡面与洪泛平原土壤有机碳动态。将使用广泛的现有数据源对所有模型组件进行评估和评估。然后，模型将在一个综合框架内实施，以检查下个世纪英国和欧洲选定地点的环境对气候变化的反应。使用这种方法将解决的关键问题包括：1。预测的未来气候变化对土壤侵蚀和泥沙流入和流经河道的影响是什么？2. 气候变化和加速侵蚀对河道形态的预计影响是什么？这些变化如何改变洪泛区未来的洪水风险和沉积物储存？3. 能否量化未来气候变化对景观内土壤有机碳再分配的影响，并将其作为反馈纳入未来陆地碳生物地球化学模型？注：参考资料是为了提供支持

For the government agencies and statutory bodies responsible for management of land and water resources, the past decade has witnessed growing recognition of a series of pressing environmental issues and an awareness that significant uncertainties exist concerning their future trajectories: 1. Erosion by water is the most severe threat to soil in Europe (Kirkby et al., 2004). Furthermore, rates of soil erosion are sensitive to changes in surface runoff, yet spatially-explicit predictions of future erosion rates under changing climatic conditions are not yet available. 2. Redistribution of soil by agricultural tillage is a key influence on the evolving spatial variability of soil properties and productivity (Quine and Zhang, 2002), and consequently exerts a strong control on the emission and sequestration of soil carbon from arable land (Van Oost et al., 2004, 2005). Soils are expected to represent an important control on carbon cycle feedbacks under changing climatic conditions (Cox et al., 2000). However, the role of soil erosion and redistribution in the carbon cycle remains an area of significant controversy, with estimates of the global carbon flux associated with erosion ranging from a 1 Gt/year source to a 1 Gt/year sink (Stallard, 1998; Lal, 2003). 3. Delivery of eroded sediment to river channels causes many environmental problems including diffuse pollution, transport and storage of fine sediment and associated contaminants, degradation of aquatic ecosystems, and changes in flow conveyance capacity and flood frequency due to in-channel and overbank sedimentation (Walling et al., 1999, 2001; Greig et al., 2005). Defra and the Environment Agency currently face the significant challenges posed by implementation of the EC Water Framework Directive (WFD) and the requirement to address the issues highlighted above in order to manage and maintain the ecological status of all surface waters. Furthermore, potential changes in the threats posed by these problems under future climates have yet to be quantified. Tackling these challenges at national and regional scales will necessitate the development of new modelling approaches capable of investigating the feedbacks between climatic, hydrologic, geomorphic and biogeochemical processes, which are poorly understood at present. This project will link CEH and Met. Office expertise in regional climate and hydrological modelling with geomorphological models developed by the universities of Leeds and Exeter to build for CEH a solid, strategic platform from which to address this set of fundamental scientific and environmental questions, which lie at the heart of the EHFI programme, and are central to both CEH and NERC's core missions. This project will build on recent modelling advances to develop new models in the following areas: 1. Hillslope hydrology and soil erosion; 2. Sediment routing within rivers, flood conveyance and floodplain sedimentation; 3. Soil redistribution on hillslopes and soil organic carbon dynamics on slopes and floodplains. All model components will be evaluated and assessed using a wide range of existing data sources. Models will then be implemented within an integrated framework to examine environmental responses to climate change over the next century in the UK and at selected sites in Europe. Key questions that will be addressed using this approach include: 1. What are the effects of projected future changes in climate on soil erosion and sediment delivery into and through river channels? 2. What are the projected effects of climate change and accelerated erosion on river channel morphology, and how might these changes alter future flood risk and sediment storage on floodplains? 3. Can the effects of future changes in climate on the redistribution of soil organic carbon within the landscape be quantified and incorporated as a feedback into future models of terrestrial carbon biogeochemistry? Note: References are in case for support