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

水造成的土壤侵蚀是世界粮食生产用地加速丧失的首要原因，威胁着全球粮食安全和水质。由于与人类有关的长期活动及其易受侵蚀的地形和气候变化，土壤侵蚀正在增加。粮农组织领导的全球土壤伙伴关系报告称，全球每年有750亿吨土壤被侵蚀。改变自然景观的人为力量会造成严重的土壤侵蚀，从而损害地表水体，因此有必要将泥沙控制作为流域管理规划的基本方面。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的影响的重要组成部分。然而，尽管有无数可用的模型，但目前模拟土壤侵蚀的方法在预测侵蚀过程的能力方面几乎没有显示出整体上的改进。由于侵蚀过程的复杂性、多尺度和时变性，很难对其进行全面的刻画。这就是为什么目前的大多数模型只基于稳态条件下的土壤流失实验，而不是现象学的恒强降雨速率。由于预测模型非常局限于校准的日期和土壤类型，拟议的研究计划旨在利用尖端实验技术和新的建模框架，更深入地了解土壤侵蚀的精细物理机制。这项研究的独特之处在于对水文和土壤条件(初始和边界)以及随后对污染物迁移的影响进行了综合分析。更具体地说，本研究计划的短期目标是开发：(I)高速、高分辨率成像和CT扫描技术，以在受控的实验室条件下同时跟踪浅层陆流中的沉积物颗粒；(Ii)与格子Boltzmann方法(LBM)相关的非常详细的离散单元模型，该模型控制土壤剥离和水路运输的主要过程；(Iii)为野外和研究应用、决策者、农学家和工程师开发用于野外和研究应用的模型的修正版本，其形式为基于网络的版本。

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.