Soil-grain transport and dispersal by rainsplash, with implications for plant-soil interactions in deserts

该项目涉及描述土壤迁移的雨水飞溅。 通过考虑雨滴激活的土壤颗粒运动的不稳定性，该公式表明雨滴强度梯度在影响输送方面可以与表面坡度一样重要。 该公式提供了一个实用的框架，描述运输，分散和隔离的土壤传播的病原体和养分的雨水飞溅。 在澄清谷物飞溅过程的物理学最近取得的成功的基础上，该项目结合了理论，实验和实地工作：（一）追求更深入地了解土壤谷物运输和分散的雨水飞溅;（二）说明如何存储和释放的沉积物下的沙漠灌木在关系到雨水飞溅代表的行为？电容器？决定了沙漠地表演化的速度 实验涉及在下落撞击过程中沉积物颗粒运输的高速成像，以及在受控降雨条件下运输和扩散的测量。 野外工作包括测量美国西部沙漠灌木下和周围的土壤特征，该项目除了有助于更清楚地了解作为一个重要地貌过程的雨溅迁移外，还将把雨溅的物理细节与侧重于农业和沙漠环境中污染物、营养物和病原体的迁移、扩散和隔离的研究联系起来，以及沙漠植被的生态学，其中沙漠植物被视为？资源岛？ 在本项目期间支持的研究生将获得与地球表面系统以及其他地球科学和工程领域相关的流体力学和传输现象的基础。 本科生将实质性地参与，导致高级论文项目。 该项目将产生引人注目的图像和视频的雨水飞溅，在视觉上澄清这一过程。 科学界和公众可以通过教育网页随时获取这些信息。该奖项将得到美国国家科学基金会地貌学和土地利用动力学（Geomorphology and Land-Use Dynamics，简称GLD）项目的支持。

This project involves describing soil transport by rainsplash. By taking into account the intermittency of soil-grain motions activated by raindrops, the formulation indicates that gradients in raindrop intensity can be as important as surface slope in effecting transport. The formulation provides a practical framework for describing transport, dispersal and sequestration of soil-borne pathogens and nutrients by rainsplash. Building on recent success in clarifying the physics of the grain splash process, the project combines theoretical, experimental and field-based work to: (i) pursue a deeper understanding of soil-grain transport and dispersal by rainsplash; and (ii) illustrate how storage and release of sediments beneath desert shrubs in relation to rainsplash represents the behavior of a ?capacitor? that contributes to setting the rate of desert land-surface evolution. Experiments involve high-speed imaging of sediment grain transport during drop impacts, and measurements of transport and dispersal under controlled rainfall conditions. Field work involves measurements of soil features beneath and surrounding desert shrubs in the western U.S., aimed at clarifying relationships among the characteristic length scales of vegetation canopies and soil mounds in relation to grain splash.In addition to contributing to a clearer understanding of rainsplash transport as an important geomorphic process, the project will connect the physical details of rainsplash with studies focused on transport, dispersal and sequestration of contaminants, nutrients and pathogens in agricultural and desert settings, and on the ecology of desert vegetation, wherein desert plants are viewed as ?resource islands.? Graduate students supported during this project will gain a foundation in fluid mechanics and transport phenomena relevant to Earth-surface systems as well as other geoscience and engineering fields. Undergraduate students will be substantively involved, leading to senior thesis projects. The project will generate compelling images and videos of rainsplash that visually clarify this process. These will be readily accessible to the science community and public via educational web pages.This award will be supported by the NSF's program in Geomorphology and Land-Use Dynamics (EAR/GLD).