The vadose zone serves as a crucial link for the mutual transformation of atmospheric, surface, ecological, and groundwater systems. Infiltration recharge in the vadose zone is a key step in the Earth's water cycle and plays an extremely important role in the sustainable development of groundwater resources, particularly in arid and semi-arid regions. However, under the influence of extreme climatic conditions and intense human activity, the vadose zone has thickened in many places globally. Changes in the vadose zone structure lead to alterations in the infiltration process. Researchers have attempted to quantify this process using various methods. However, it has been found that conventional monitoring methods are inadequate to effectively describe the complex infiltration recharge process under the multifactorial influence of a deep vadose zone. Through an analysis of relevant literature published from 2000 to 2023 regarding deep vadose zone infiltration recharge, this paper identifies four contentious bottlenecks: (1) effective monitoring and simulation of deep vadose zone infiltration recharge, (2) modes of deep infiltration recharge, (3) issues related to the quantity and recharge period of precipitation and irrigation infiltration recharge, and (4) quantification of spatial variations and scale effects of infiltration recharge. After reviewing the latest developments in infiltration recharge monitoring and simulation and systematically analyzing the influencing factors and mechanisms of deep vadose zone infiltration recharge, this study provides answers to the aforementioned issues. The combined use of monitoring and numerical simulation methods, taking into account infiltration recharge scenarios and scales, can enhance the reliability and accuracy of the calculation results. Additionally, piston flow may not be the primary mode of water movement in the deep vadose zones. Understanding the modes and characteristics of water movement, as well as the differences in suction and desorption processes, is fundamental for accurately describing nonlinear infiltration recharge processes. Furthermore, the measured average vertical infiltration rates of the deep vadose zone vary widely from 0.14 to 500 mm/d globally. In the North China Plain, vertical infiltration recharge rates range from 133 to 300 mm/a. These significant differences are related to the research scale, external conditions, and internal soil structure within the vadose zone. Finally, a systematic analysis of the driving factors of nonlinear infiltration recharge in the deep vadose zone is a prerequisite for quantifying spatial variations and scale effects. Only by fully considering the interactions and contributions of various driving factors can the spatiotemporal variations in soil infiltration be effectively quantified. Therefore, our research team suggests that future studies on deep vadose zone infiltration recharge should focus on establishing a unified layout for large-scale, multi-point, synchronous, in situ, and long-term monitoring; constructing relationships between the vadose zone structure and hydraulic characteristics; and conducting comprehensive studies on the overall water cycle in the Earth's surface layers, with the deep vadose zone as the core. These will help build a research system for the spatiotemporal infiltration recharge of water in the deep vadose zone at multiple layers and scales, achieving the closest approximation to a realistic description of the deep vadose zone infiltration recharge.

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关注深渗流带非线性入渗过程

包气带是大气、地表、生态和地下水系统相互转化的重要纽带。渗流带入渗补给是地球水循环的关键步骤，对地下水资源的可持续开发，尤其是干旱、半干旱地区发挥着极其重要的作用。然而，在极端气候条件和强烈人类活动的影响下，全球许多地方的渗流带已经加厚。渗流区结构的变化导致渗透过程的改变。研究人员尝试使用各种方法来量化这一过程。然而，人们发现，常规监测方法不足以有效描述深部包气带多因素影响下复杂的入渗补给过程。通过对2000年至2023年发表的有关深渗流带渗透补给的相关文献的分析，本文识别出四个有争议的瓶颈：（1）深渗流带渗透补给的有效监测和模拟，（2）深渗流补给的模式，（3） ）与降水和灌溉渗透补给的数量和补给期相关的问题，以及（4）渗透补给的空间变化和规模效应的量化。本研究回顾了渗透补给监测与模拟的最新进展，系统分析了深层渗流带渗透补给的影响因素和机制，为上述问题提供了答案。监测与数值模拟方法结合使用，考虑入渗补给场景和规模，可以提高计算结果的可靠性和准确性。此外，活塞流可能不是深渗流区水运动的主要模式。了解水运动的模式和特征，以及吸力和解吸过程的差异，是准确描述非线性渗透补给过程的基础。此外，全球范围内测得的深渗流区平均垂直渗透率差异很大，从 0.14 到 500 mm/d。在华北平原，垂直入渗补给率范围为133至300毫米/年。这些显着差异与研究规模、外部条件以及包气带内部土壤结构有关。最后，系统分析深部包气带非线性入渗补给的驱动因素是量化空间变化和尺度效应的先决条件。只有充分考虑各种驱动因素的相互作用和贡献，才能有效量化土壤入渗的时空变化。所以，研究团队建议，未来深部包气带渗透补给研究应重点建立统一布局，进行大范围、多点、同步、原位、长期监测；构建渗流带结构与水力特征之间的关系；全面开展以深层渗流带为核心的地表水循环整体研究。这些将有助于建立多层次、多尺度的深渗流带水时空渗透补给研究体系，实现对深渗流带渗透补给的最接近真实的描述。