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

对于负责土地和水资源管理的政府机构和法定机构来说，在过去十年里，人们越来越认识到一系列紧迫的环境问题，并意识到这些问题未来的发展轨迹存在重大不确定性：1.水蚀是欧洲土壤最严重的威胁(Kirkby等人，2004年)。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上的明确预测尚不存在。2.农业耕作引起的土壤再分布是影响土壤性质和生产力空间变异性演变的关键因素(Quine和Zhang，2002)，并因此对耕地土壤碳的排放和封存起到很强的控制作用(Van Oost等人，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等人，2000年)。然而，土壤侵蚀和再分配在碳循环中的作用仍然是一个有很大争议的领域，对与侵蚀有关的全球碳通量的估计从1 GT/年的源到1 GT/年的汇(Stallard，1998；Lal，2003)。3.向河道输送侵蚀泥沙造成许多环境问题，包括扩散污染、细小沉积物和相关污染物的运输和储存、水生生态系统退化以及河道内和岸上沉积引起的水流输送能力和洪水频率的变化(Wling等人，1999,2001；Greig等人，2005)。目前，环境保护局和环境局面临着执行欧共体水框架指令(WFD)所带来的重大挑战，以及为管理和维持所有地表水的生态状况需要解决上述问题的要求。此外，这些问题在未来气候下构成的威胁的潜在变化还有待量化。要在国家和区域范围内应对这些挑战，就必须开发新的建模方法，能够研究气候、水文、地貌和生物地球化学过程之间的反馈，目前对这些过程知之甚少。该项目将把CEH和MET联系起来。办事处利用利兹大学和埃克塞特大学开发的地貌模型在区域气候和水文模拟方面的专业知识，为CEH建立了一个坚实的战略平台，以解决这一系列基本的科学和环境问题，这些问题是EHFI计划的核心，也是CEH和NERC核心任务的核心。本项目将以最新的模拟进展为基础，在以下领域开发新的模型：1.山坡水文学和土壤侵蚀；2.河流中的泥沙路线、洪水输送和洪泛区沉积；3.山坡上的土壤再分布和坡地和洪泛区的土壤有机碳动态。将利用各种现有数据来源对所有模型组成部分进行评价和评估。然后，将在一个综合框架内实施模型，以检查英国和欧洲选定地点在下个世纪对气候变化的环境反应。使用这种方法将解决的关键问题包括：1.预计未来气候变化对土壤侵蚀和泥沙进入和通过河道输送的影响是什么？2.气候变化和加速侵蚀对河道形态的预测影响是什么，这些变化可能如何改变未来洪水风险和洪泛区的泥沙储存？3.未来气候变化对土壤有机碳在景观中重新分布的影响能否被量化并作为反馈纳入未来陆地碳生物地球化学模型？注意：参考资料是为了获得支持

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