Wind-Driven Rain as a new Challenge in Soil Erosion Research

风驱动的雨——土壤侵蚀科学的巨大不可估量的因素。土壤侵蚀现在被认为是威胁粮食安全和环境服务的最严重的环境危害之一。土壤侵蚀的影响已经引起了决策者最关心的社会生态问题，随着气候的持续变化，情况变得更加严重。但是，尽管人们投入了大量人力和财力来开发、参数化和运行数值侵蚀模型，但人们对剥离和运输过程的基本原理还远远没有了解。风对雨滴、坡面流和土壤颗粒侵蚀的影响是土壤侵蚀科学中不可估量的重要因素之一。到目前为止，风这个因素已经被广泛地排除在降雨模拟的实验研究之外，部分原因是所需实验设备的开发和设置困难。现有的少数研究表明，风是全球尺度土壤侵蚀评估和实际土壤侵蚀模拟参数化不可或缺的因素。在不同基质上，与无风雨侵蚀相比，风雨侵蚀产生的剩余侵蚀在+37.4% ~ +1108%之间。本研究的目的是研究风对雨水侵蚀的影响。利用特里尔大学开发的便携式风雨模拟器，将设计一套新的实验室和现场实验，并将突出风对雨水侵蚀的影响。它包括通过高速摄像机进行测量和视觉观察。分析的过程包括飞溅、飞溅-跳跃（由风雨引起的飞溅）和飞溅-漂移（在风雨事件中由空气和风运输的沉积物）以及受风雨影响和风加速的陆地片流。对不同类型的标准基材在不同风速下的实验室研究辅以对本地土壤表面的现场试验。对收集到的室内和野外试验数据进行统计分析，提取关键因素。相机观测经过摄影测量处理。通过不同的实验和分析方法获得的数据，从实验室和现场测试获得的侵蚀测量数据，对水滴和颗粒运动的摄影测量评估以及统计提取的关键因素，然后收集在一个综合中。通过生成一个概念模型来完成研究，以全面地接近风驱动雨复合体。通过这种方式，本项目实现了两个优越的目标：一是开展面向目标的风雨动力学基础研究，深刻理解分析过程。-生成充分的侵蚀模型急需的结果。通过结合互补的方法，可以澄清风对雨侵蚀过程的影响。

Wind-driven rain - the great imponderable of soil erosion science. Soil erosion is now being recognised as one of the most severe environmental hazards threatening food security and environmental services. The effects of soil erosion are already raising socio-ecological issues of greatest concern for decision makers, and the situation is becoming even more severe with the ongoing climate change. But while great personnel and financial efforts are made to develop, parameterise and run numerical erosion models, the very basics of detachment and transport processes are far from understood. One of the great imponderables of soil erosion science is the influence of wind on raindrop, overland sheet flow and erosion of soil particles. Until now, the factor wind has widely been excluded from experimental investigations with rainfall simulations, partly because of the difficult development and setup of the needed experimental device. The few studies available indicate, that wind is an indispensable factor for the assessment of soil erosion on a global scale and the parameterisation of realistic soil erosion simulations. On different substrates, the surplus erosion generated by wind-driven rain ranged from +37.4% to +1108%, compared to windless rain erosion. The aims of the proposed study focus on this effect of wind on rain erosion. With the Portable Wind and Rainfall Simulator, that has been developed at Trier University, a new set of laboratory and field experiments will be designed and will highlight the influence of wind on rain erosion. It includes measurements and visual observation by means of a high-speed camera. Analysed processes are splash, splash-saltation (splash induced by wind-driven rain) and splash-drift (airborne and wind transported sediment during a wind-driven rain event) as well as wind-driven rain impacted and wind-accelerated overland sheet flow. The laboratory investigations on different types of standard substrates with varying wind velocities are complemented by field tests on autochthonous soil surfaces. The collected data from laboratory and field experiments are statistically analysed and key factors extracted. The camera observations are photogrammetrically processed. The data gained via different sets of experiments and ways of analysis, measured erosion data from laboratory and field tests, photogrammetrical evaluation of drop and particle movement and the statistically extracted key factors, are then gathered in a synthesis. The study is completed by the generation of a conceptual model to approach the wind-driven rain complex in a comprehensive way. This way, the proposed project achieves two superior objectives: - A goal-oriented basic research of the wind-driven rain dynamics to profoundly understand the analysed processes. - The generation of results urgently required for adequate erosion modelling.By combining complementary approaches, the effects of wind on rain erosion processes can be clarified.