Collaborative Research: Impact of Spatial and Temporal Heterogeneity of Soil Cracking on Watershed Hydrology

合作研究：土壤开裂时空异质性对流域水文的影响

• 批准号: 0911317
• 负责人: Cristine Morgan
• 金额: $ 29.96万
• 依托单位: Texas A&M Research Foundation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-04-01 至 2015-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0911317&HistoricalAwards=false
• 关键词: Collaborative; Research; Impact; Spatial; Temporal

PROJECT ABSTRACTTitle: Collaborative Research: Impact of Spatial and Temporal Heterogeneity of Soil Cracking on Watershed HydrologyClay-rich soils that crack on drying and swell on wetting cover a considerable fraction of the Earth?s land surface. The goal of this research is to improve the hydrological response of watershed models used in regions that have such soils. To accomplish this goal, the ability to spatially and temporally partition precipitation into infiltration and runoff must be improved. Partitioning of precipitation into infiltration and runoff is highly dependent on the spatial and temporal distribution and size of cracks in these soils. When a cracking clay soil is very dry, precipitation is partitioned nearly all to infiltration via the large physical capacity of the cracks. When a cracking clay soil is very wet and infiltrating water must travel through the fine pores of the clay matrix, significant amounts of precipitation are partitioned to runoff. What happens between these two soil moisture extremes is essential in predicting hydrological, agronomic, and environmental responses of watersheds with clayey soil to rainfall events, but has not been adequately characterized by hydrologists or soil scientists, and is the focus of this research. Recent developments in technologies to electromagnetically sense, collect, and manage spatial soil and environmental information support quantification of the state of a cracking soil at any given moment and location, and allow an improvement in the ability to track the spatial distribution and size of cracks. In our research effort, we will measure and characterize the spatial heterogeneity and temporal dynamics of soil cracking as a function of terrain attributes, soil water dynamics, and basic chemical, mechanical, and physical soil properties. Measurements will be made in a highly instrumented experimental watershed in Central Texas. Focusing our understanding of crack behavior on basic information and properties we will promote transfer of knowledge to other watersheds. In addition to being able to track the degree and distribution of cracking, the scale that this information needs to be addressed in hydrological models to improve their accuracy must be determined. To address this need, a hydrological model composed of a two-dimensional, diffusive wave runoff module and a one-dimensional, point-column biophysical module will be used to evaluate cracking as a function of landscape position, soil characteristics, and antecedent moisture conditions; allowing a dynamic partitioning of rainfall between infiltration and runoff during precipitation events. The model operates on a 3-dimensional grid and includes the ability to handle spatial variations in soil properties, moisture content, and other factors that may be used to predict the instantaneous size and water holding capacity of cracks. Equations for crack distribution, size, and capacity distilled from the observations in this study will be added to the model. The model will link the behavior of cracking within each grid cell to watershed hydrographs via runoff to surrounding grids cells in the field, the sub-basin, and the watershed. The contributions of each cell to infiltration and runoff are calculated, yielding spatial patterns of the fate of precipitation. By comparison of measured hydrographs from the experimental watershed with hydrographs generated from the model as the size of the grid cells are increased, the scale that information on soil cracking needs to be addressed to produce a degree of accuracy will be characterized.This research is collaborative, combining a soil hydropedologist, an environmental physicist, and a landscape hydrologic modeler; and bridges scales from millimeter to kilometer by linking soil microenvironments, field scale heterogeneity, and watershed hydrology. The research findings will be fully integrated into graduate and undergraduate courses in soil hydrology, soil morphology, environmental physics, and spatial statistics taught by the investigators. Collaboration with a local school district will provide outreach exposing rural students to the sciences and real-world, field-based science problems.

项目摘要标题：合作研究：土壤开裂的时空异质性对流域水文的影响富含粘土的土壤在干燥时开裂，在湿润时膨胀，覆盖了地球的相当一部分。的土地表面。 本研究的目的是改善流域模型的水文响应，在有这样的土壤的地区。 为了实现这一目标，必须提高降水在空间和时间上划分为入渗和径流的能力。 降水入渗和径流的分配在很大程度上取决于这些土壤中裂缝的时空分布和大小。 当开裂的粘土非常干燥时，通过裂缝的大物理容量，降水几乎全部被分配为入渗。 当开裂的粘土非常潮湿，渗透水必须通过粘土基质的细孔，大量的降水被分配到径流中。 这两个土壤水分极端之间发生的是必不可少的预测水文，农艺和环境的流域粘土降雨事件的反应，但还没有充分的水文学家或土壤科学家的特点，是本研究的重点。 电磁感应、收集和管理空间土壤和环境信息的技术的最新发展支持在任何给定时刻和位置量化开裂土壤的状态，并允许提高跟踪裂缝的空间分布和尺寸的能力。 在我们的研究工作中，我们将测量和表征土壤开裂的空间异质性和时间动态作为地形属性，土壤水动力学和基本化学，机械和物理土壤特性的函数。 测量将在德克萨斯州中部的一个高度仪器化的实验流域进行。 将我们对裂缝行为的理解集中在基本信息和性质上，我们将促进知识向其他流域的转移。 除了能够跟踪裂缝的程度和分布，还必须确定水文模型中需要解决的信息规模，以提高其准确性。 为了满足这一需求，一个水文模型组成的二维，扩散波径流模块和一维，点列生物物理模块将被用来评估作为景观位置，土壤特性和前期水分条件的函数开裂;允许在降水事件的渗透和径流之间的降雨动态分区。 该模型在三维网格上运行，包括处理土壤特性、含水量和其他可用于预测裂缝瞬时尺寸和持水能力的因素的空间变化的能力。 将从本研究中的观察结果中提取的裂缝分布、尺寸和容量的方程添加到模型中。 该模型将通过径流将每个网格单元内的裂缝行为与流域水文线联系起来，并将其与田地、子流域和流域中的周围网格单元联系起来。 每个细胞的渗透和径流的贡献进行计算，产生的降水的命运的空间格局。 通过比较从实验流域测得的水文过程与从网格单元的大小增加的模型生成的水文过程，土壤开裂的信息需要解决，以产生一定程度的准确性的规模将被表征。桥梁通过连接土壤微环境、田间尺度异质性和流域水文学，从毫米到公里。 研究结果将完全整合到研究生和本科课程土壤水文学，土壤形态学，环境物理学和空间统计学教授的调查。 与当地学区的合作将使农村学生接触科学和现实世界的实地科学问题。