干旱区包气带土壤水分运移能量关系及驱动力研究评述

包气带土壤能量和水分平衡及其驱动因子是维系地下水-土壤-植物-大气连续体(GSPAC)系统中水分运移发生的关键因素。在降水稀少、水资源短缺的干旱地区,开展包气带土壤水分形态、运移过程与能量的耦合规律研究对揭示区域水资源形成和转化机理具有极其重要的现实意义。文章总结了土壤水分运移理论研究进展,探讨了水分参与水文循环过程及干旱环境下土壤水分可能表现形态及其降雨入渗、再分布、渗漏、蒸发、毛管水上升等过程驱动机制,评述了包气带土壤水分与能量过程在不同空间尺度上生态水分效应。在一个非饱和土壤系统中,水分运移受包气带结构,土壤物理特征,植物根系和土壤生化环境的综合控制,物质和能量平衡改变是驱动水分循环的源动力,而土壤环境变化是导致水分运移形态的发生变化根本原因。因此,在气候变化背景下,研究干旱区土壤与大气界面以及包气带与饱和带界面水、汽、热耦合转化形式与能量驱动过程,能够提升我们对包气带土壤水分运移规律机理的深入理解,丰富对区域气候和水文变化认知。为干旱区生态植被恢复建设和水资源精细化管理提供理论向导。

Review of studies on the relationship between soil water movement and energy and their driving forces in the vadose zone of arid regions

In the vadose zone, the soil energy and water balance and its driving forces are key factors that maintain soil moisture movement in the groundwater-soil-plant-atmospheric continuum (GSPAC) system. However, in arid regions with lower precipitation and water resources, studies on coupling soil water state and movement processes and the partitioning and migration of energy are important to understand the formation and transformation mechanisms of regional water resources. In this paper, advances in soil water transport theory are summarized. We also discuss the water cycle in the system and the possible ways by which soil water is lost under arid conditions, as well as the driving mechanisms behind rainwater infiltration, redistribution, drainage, evaporation, and capillary rise. This paper also reviews the ecological hydrological effect of soil moisture and energy processes on different spatial scales. In unsaturated soil systems, soil water movement is controlled by the vadose zone structure, soil physical characteristics, plant root system and soil biochemical environment. Changes in matter and energy balance are the driving forces of the hydrological cycle, and change in the soil environment is a fundamental factor for change in the soil water state. Therefore, under global climate change, studies on the energy and driving mechanism of coupling liquid water, water vapor, and heat transport through the interface between the soil surface and atmosphere or groundwater could elucidate the transport mechanism of soil water and help us to better understand regional climate and hydrological changes. The ultimate objective is to provide theoretical guidance for the restoration and construction of ecological vegetation and precision management of water resources.