Mechanics of soil erosion by water: Mathematical modelling and laboratory experimentation

水对土壤的侵蚀是加速世界粮食生产土地流失的首要因素，威胁着全球粮食安全和水质。由于长期的人类活动及其易受侵蚀的地貌和气候变化，土壤侵蚀正在加剧。粮农组织领导的全球土壤伙伴关系报告说，全世界每年有750亿吨土壤从可耕地上流失。改变自然景观的人为力量造成严重的土壤侵蚀，损害地表水体，因此必须将沉积物控制作为集水区管理规划的重要方面。模拟模型是试图了解农业过程、土地利用和气候变化对土壤侵蚀影响的重要组成部分。然而，目前的方法来模拟土壤侵蚀，尽管有无数的可用模型，并没有表现出整体改善的能力来预测侵蚀过程。由于侵蚀过程的复杂性、多尺度性和时间依赖性，很难对其进行全面的表征。因此，目前的土壤侵蚀模型大多是建立在稳态条件下的土壤侵蚀试验基础上的，且常强度降雨率的模型较少。是什么使得预测模型非常局限于它们被校准的日期和土壤类型？拟议的研究计划旨在利用尖端的实验技术和新的建模框架，更深入地了解土壤侵蚀的精细尺度物理机制。该研究项目的独特之处在于综合分析了水文和土壤条件（初始和边界）以及随后对污染物运移的影响。更具体地说，本研究方案的短期目标是：（一）在受控的实验室条件下，开发高速、高分辨率成像和CT扫描技术，以同时跟踪浅层坡面流中的沉积物颗粒;（ii）一个非常详细的离散元模型，与控制土壤分离和水迁移的主要过程的格子玻尔兹曼方法（LBM）有关;该模型的修改版本，用于现场和研究应用，以基于Web的版本形式，用于现场和研究应用，决策者，农学家和工程师。

Soil erosion by water is foremost to an accelerated loss of the world's food-producing lands, threatening global food security and water quality. Soil erosion is increasing as a result of long-term human-related activities and its erosion-prone landforms and climate change. The FAO led Global Soil Partnership reports that 75 billion tonnes per year of soil are eroded from arable lands worldwide. Anthropogenic forces that alter the physical landscape cause substantial soil erosion, which harms surface water bodies and therefore necessitating sediment control as essential aspects of catchment management planning. Simulation models are a vital component of attempts to understand the impact of agricultural processes, land-use and climate change on soil erosion. However, nowadays approaches to modelling soil erosion, despite an endless number of available models, have shown little overall improvement in their ability to predict erosion processes. Due to the complexity, multiple scales and time dependence erosion processes are hard to be thoroughly characterized. That is why most of the nowadays models are only based on soil loss experiments in steady-state conditions, with constant-intensity rainfall rater then phenomenological ones. What makes predictive models very limited to the date and soil types they were calibrated The proposed research program is designed to gain deeper insights into the fine-scale physical mechanisms governing soil erosion using cutting edge experimental technics and new modelling frameworks. The uniqueness of this research program lies in the integrated analysis of hydrological and soil conditions (initial and boundary) and subsequent effects on contaminant transport. More specifically, the short-term objectives of the present research program are to develop: (i) high-speed, high-resolution imaging and CT-Scan techniques to simultaneously track sediment particles in shallow overland flow under controlled laboratory conditions; (ii) a very detailed discrete element model associated with the Lattice Boltzmann method (LBM) of the main processes governing soil detachment and transport by water and (iii)a modified version of the model for field and research applications in the form of a WEB-based version for field and research applications, decision maker's, agronomists and engineers.