Measurement and Modeling of Flow and Transport in Macroporous Soils

0106956 Mohanty通过土壤大孔隙和裂缝的优先流动和运输的表征是包气带水文学的最大挑战之一。 已经开发了几个具有不同复杂程度的概念模型（例如，等效连续体、双孔隙度和双渗透率方法）来描述大孔隙流动-运输过程。 然而，没有一个一致的概念模型与确证的测量技术是可以精确地描述这一过程。 由于重力和/或毛细管力在接近饱和的多孔介质中主导运输过程，各种因素有助于大孔流的引发及其强度，包括孔的几何形状、分布和连续性。 此外，土壤能量状态、顶部和底部边界条件的性质以及纹理分层也起着重要作用。 我们建议量化这些因素中的许多因素对优先流和运输的影响，在一系列精心控制的柱实验中使用新颖的设计。 同时测量土壤含水量，水势，浓度在不同的“大孔”和“无大孔”区域，以及高时间分辨率的流入和流出的体积和浓度，是我们提出的研究的一些新功能。 具有已知几何形状、分布和初始/边界条件的人工大孔隙将使数据分析和解释更加彻底和有意义。 将用新的数据集测试几个现有的或新开发的概念模型，最终导致制定更现实的优先流模型，其中包含基于物理和可测量的参数。 本研究的结果，在不同的初始条件，边界条件，大孔隙的几何形状和连续性，以及其他（受控）的流动和运输条件的触发，维持，加速/减速或中断快速流动运输现象的不同组合的几十ns将是有价值的更好地理解和量化的水文和环境过程在不同的尺度。

0106956Mohanty Characterization of preferential flow and transport through soil macropores and fractures is one of the biggest challenges in vadose zone hydrology. Several conceptual models have been developed with different levels of complexity (e.g., equivalent continuum, dual porosity, and dual permeability approaches) to describe the macropore flow-transport process. However, no congruent conceptual model with a corroborating measurement technique is available to precisely describe this process. As gravity and/or capillary forces dominate the transport processes in the porous medium near saturation, various factors contribute to the initiation of macropore flow and its intensity, including pore geometry, distribution, and continuity. In addition soil energy status, the nature of top and bottom boundary conditions and textural layering, play important roles. We propose to quantify the effects of many of these factors on preferential flow and transport in a series of carefully controlled colunm experiments using novel designs. Concurrent measurement of soil water content, water potential, and concentration across distinct "macropore" and "no-macropore" regions, as well as of the volume and concentration of inflow and outflow with high temporal resolution, are some of the new features of our proposed study. Artificial macropores with known geometry, distribution, and initial/boundary conditions will make the data analysis and interpretation more thorough and meaningful. Several existing or newly developed conceptual models will be tested with the new data sets, ultimately leading to the formulation of more realistic preferential flow models that contain physically-based and measurable parameters. Findings of this research in ten-ns of different combinations of initial conditions, boundary conditions, macropore geometry and continuity, and other (controlled) flow and transport conditions that trigger, sustain, accelerate/decelerate or discontinue the fast flow-transport phenomenon will be valuable for better understanding and quantification of hydrologic and environmental processes at different scales.