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    干旱半干旱地区深层渗漏研究方法综述

    Review on the methods to determine deep percolation in arid and semi-arid areas

    • 摘要: 深层渗漏(DP)是水文循环的重要环节,准确评价DP对于分析水文循环规律,合理制定水资源规划和地下水可持续利用具有重大意义,尤其是在水资源短缺的干旱半干早地区,开展该项研究更具价值。目前,干旱半干旱地区DP的评价方法主要有经验方法、物理方法、示踪方法和数值模拟方法。由于经验系数需要校正,因而经验方法应用到其他区域受到限制;物理方法又可分为蒸渗仪法、土壤水分通量法、水量平衡法、达西方法以及地下水位动态监测法;示踪方法主要从示踪剂的峰值、剖面形状和总含量来计算DP,此方法不是对DP的直接测定,且没有考虑示踪剂的空间变异;数值模拟理论上可对各种条件下的DP进行模拟和预测,但获取参数的难度较大。针对各方法存在的优缺点,将现有评价方法相结合,相互验证,可提高模拟精度;鉴于DP的时空变异性,将现有方法与GIS 等新技术集成,可评价大尺度DP的空间异质性;同时,进行长时间序列的野外观测,既可直接获取DP 的动态信息,也可为各方法参数的获取提供数据支持。

       

      Abstract: Background Deep percolation (DP ) is termed as the movement of water from soil surface to sufficient depths, usually below the root zone. It generally occurs when infiltrated water exceeds the storage capacity of the soil and plays an vital role in hydrologic cycle. ccurate evaluation of the deep percolation is crucial to analyze the processes of the hydrologic cycle. Furthermore, deep percolation is pivotal for the management and rational evelopment of groundwater resources, especially in arid and semi-arid regions where water resources is deficient. Methods This paper reviews several approaches to assess deep percolation in arid and semi-arid regions, i. e., empirical, physical, tracer, and numerical modelling. Results The principle, applicability, merits and drawbacks of the above- mentioned four approaches are commented. Due to the empirical coefficient requires calibration, the empirical pproach is limited while it is applied in the other regions. Physical approach includes lysimeter method, soil water flux method, water balance method, Darcy method, and underground water-tablefluctuation method. The tracer approach is used to estimate deep percolation by the identification of peak value, profile shape, and the amount of tracers, but this approach cannot directly measure the deep percolation; moreover, the spatial variation in tracers is not considered in it. Theoretically, the approach of numerical modelling can be used to estimate and predict the deep percolation under any ircumstance. Nevertheless, it is difficult to obtain the parameters that is necessary for the numerical modelling. Conclusions Considering the advantages and isadvantages of each method, the integration of existing evaluation methods and mutual verification of them can improve the precision of the simulation. Due to the spatial and temporal variability of DP, the integration of existing methods and GIS may evaluate the spatial heterogeneity of DP at large scale. Simultaniously, long-term series of field observation may not only acquire the dynamic information of DP, but also provide the data support for the parameters of each approach.

       

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