Morphodynamics of Actively Migrating Headcuts in Rills and Gullies

沟壑中主动迁移的断面形态动力学

• 批准号: 0640617
• 负责人: Sean Bennett
• 金额: $ 9.37万
• 依托单位: SUNY at Buffalo
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-07-15 至 2010-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0640617&HistoricalAwards=false
• 关键词: Morphodynamics; Actively; Migrating; Headcuts; Rills

Soil erosion remains the principal cause of soil degradation within the U.S. and worldwide, soil loss continues to be a critical concern for the sustainable management of agricultural resources, and off-site sedimentation from upland sources severely affects water quality, ecology, and ecological habitat. Areas of intense, localized erosion, such as rills and gullies, often are the primary cause of soil loss and the dominant source of sediment yield from such landscapes, and these geomorphic features are in close association with actively migrating headcuts?step-changes in bed surface elevation where this localized erosion and headward advance takes place.The primary goal of this research program is to understand the morphodynamics of actively migrating headcuts within experimental systems and to develop physically-based analytic expressions for this discrete erosion process. Using specially-built flumes equipped with rainfall simulators and prepared soil beds, we shall define experimentally the characteristics of developing and actively migrating headcuts in upland concentrated flows unconstrained by channel width and in response to an upstream sediment supply. We shall use this information to develop predictive equations for soil loss in concentrated flows based on modified jet impingement theory. The intellectual merit of the proposed work seeks to address the fundamental mechanics of soil erosion and land degradation by headcut growth and migration in upland concentrated flows typical of rills, crop furrows, and gullies. The broader impacts of the proposed work seeks to provide the critical addition to soil erosion prediction technology necessary to improve watershed management tools and reduce the further degradation of our Nation's soil resources, whose estimated annual costs in the U.S. are as much as $40 billion.

土壤侵蚀仍然是美国和世界范围内土壤退化的主要原因，土壤流失仍然是农业资源可持续管理的一个关键问题，高地来源的场外沉积严重影响水质、生态和生态栖息地。 强烈的局部侵蚀区域，如小溪和沟壑，通常是土壤流失的主要原因，也是此类景观沉积物产量的主要来源，这些地貌特征与主动迁移的头切面密切相关？发生这种局部侵蚀和向头前进的床面高程的阶跃变化。本研究计划的主要目标是了解主动迁移的头切面的形态动力学。 实验系统并为这种离散侵蚀过程开发基于物理的分析表达式。 使用配备降雨模拟器和准备好的土床的特制水槽，我们将通过实验确定在不受河道宽度限制并响应上游沉积物供应的高地集中流中发展和主动迁移头切的特征。 我们将利用这些信息，基于修正的射流冲击理论，开发集中流中土壤流失的预测方程。 拟议工作的智力价值旨在解决因小溪、作物沟和沟壑等高地集中水流中的头切生长和迁移而导致土壤侵蚀和土地退化的基本机制。 拟议工作的更广泛影响旨在为土壤侵蚀预测技术提供关键补充，以改进流域管理工具并减少我国土壤资源的进一步退化，美国每年的土壤资源估计成本高达 400 亿美元。