Flow and transport in the vadose zone: Soil atmosphere boundary and capillarity effects

包气带的流动和传输：土壤大气边界和毛细管效应

• 批准号: RGPIN-2019-06244
• 负责人: Bashir, Rashid
• 金额: $ 2.26万
• 依托单位: York University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=714847
• 关键词: Flow; transport; vadose; zone; Soil

Over the past few decades our ability to understand and model flow and transport processes in the vadose zone (subsurface above the groundwater table) has increased considerably. Evidence from the literature suggests, that a large number of conceptual models have been developed which can be translated to numerical models to study the transient variably saturated water flow, heat and solute transport in the vadose zone. This research aims to develop new and validate existing conceptual and numerical models for: (1) coupling of physical and chemical processes, and (2) integration of surface and subsurface processes. The crux of this research is to quantify the effect of soil-atmosphere boundary and concentration dependent capillarity on flow and transport in the vadose zone via interfacial phenomena. These phenomena have considerable influence on many geotechnical and geoenvironmental designs. This research will improve our understanding of the coupled, non-linear, physical and chemical processes operative in the vadose zone to improve our design capabilities. It is proposed to achieve this goal via a number of related studies, each with its own specific objectives. Design application 1. This study aims to quantify the effect of climate change on behavior of expansive soils also known as swelling and shrinking soils. These soils go through large volume change, with changes in soil water content. Climate is the primary factor that affects the behavior of expansive soils. Most of the populated area of prairie Canada is covered with thick glacial deposits that are expansive in nature. Shallow foundations and infrastructure (buried pipelines) in the city of Regina and Winnipeg have a long history of being affected by the swelling and shrinkage of expansive soils and will benefit from this research. Design application 2. As the climate change puts more pressure on the existing water resources, the use of grey water (GW) for irrigation and aquifer recharge is becoming increasingly common. GW refers to household wastewater form laundry and kitchen and contains large quantities of surfactants. Capillarity is the primary force that enables the soil to retain water and regulates its movement. GW effects capillarity by changing the interfacial properties such as surface tension and contact angle. This research will enhance our understanding of the fundamental processes in the flow and transport of GW in vadose zone. Design application 3. Soil covers are an important part of any waste management facility. A soil cover can be viewed as a thin interface placed between the atmosphere and the underlying waste. They separate the toxic waste from the atmosphere and climate is a primary design variable. They are expected to be functional for very long periods and are highly likely to be affected by climate change. The objective of the research is to develop design guidelines for soil covers by integrating the surface and subsurface processes.

在过去的几十年中，我们能够理解和建模vadose区域（地下表面地下）的流动和运输过程的能力已大大提高。文献中的证据表明，已经开发了大量概念模型，这些模型可以转化为数值模型，以研究瞬变区域中瞬时饱和水流，热和溶质传输。这项研究旨在开发新的并验证现有的概念和数值模型：（1）物理和化学过程的耦合，以及（2）表面和地下过程的整合。这项研究的关键是通过界面现象量化土壤 - 大气边界和浓度依赖性毛细血管对vadose区流量和运输的影响。这些现象对许多岩土技术和地理环境设计具有相当大的影响。这项研究将提高我们对vadose区中耦合，非线性，物理和化学过程的理解，以提高我们的设计能力。建议通过许多相关研究实现这一目标，每个研究都有自己的特定目标。 设计应用1。本研究旨在量化气候变化对膨胀土壤行为的影响，也称为肿胀和收缩土壤。这些土壤经历了巨大的变化，土壤水含量的变化。气候是影响膨胀土壤行为的主要因素。 加拿大大草原的大多数人口稠密的地区都覆盖着厚厚的冰川沉积物，这些沉积物本质上是广阔的。里贾纳市和温尼伯市的浅层基础和基础设施（埋藏的管道）具有悠久的历史，受到膨胀土壤肿胀和收缩的影响，并将从这项研究中受益。 设计应用2。随着气候变化对现有水资源施加了更大的压力，使用灰水（GW）进行灌溉和含水层补给越来越普遍。 GW是指家庭废水和厨房形式，并含有大量的表面活性剂。毛细血管是使土壤保留水并调节其运动的主要力量。 GW通过更改界面特性（例如表面张力和接触角）来影响毛细血管。这项研究将增强我们对vadose区GW流和运输中基本过程的理解。 设计应用3。土壤覆盖是任何废物管理设施的重要组成部分。土壤覆盖物可以看作是放置在大气和基础废物之间的薄界面。它们将有毒废物与大气和气候分开是主要的设计变量。预计它们将长期发挥作用，并且很可能会受到气候变化的影响。该研究的目的是通过整合表面和地下过程来制定土壤覆盖的设计指南。