The accurate quantification of soil water dynamics is critical as it is a key parameter in the soil-plant-atmosphere continuum. This study was conducted to analyse the spatio-temporal variability of soil water dynamics in dry areas. The Soil and Water Assessment Tool (SWAT) was used to estimate the dynamics of soil water balance. The model was calibrated and validated by the regionalization with physical similarity approach. Unlike the revap water (water drawn upwards from shallow groundwater tables), the soil water, percolation and lateral flow increased with precipitation. The Mann Kendall trend test also shows that there was no trend in both the annual and monthly soil water content (SWC) and percolation; however, there was a decreasing trend (1.091 mm per annum) in the revap water. The contribution of the revap water to evapotranspiration (ET) varied from 9% during summer to 32% during spring. The SWC also exhibited a higher spatial variation. Larger part of the catchment recorded a long-term annual mean soil water content varying between 0.1 and 0.2 mm mm⁻¹. The soil water anomaly (SWA) consistently follows the trends of dry and wet seasons in the study area. Although the use of model-derived drought monitoring indices are relevant for farmers and decision makers in arid areas, it requires intensive verification over much larger scales to increase the reliability of model results.

准确定量土壤水分动力学至关重要，因为它是土壤－植物－大气连续体中的关键参数。本研究旨在分析干旱地区土壤水分动力学的时空变化。土壤和水评估工具（SWAT）用于估算土壤水平衡的动态。使用物理相似性方法通过区域化对模型进行了校准和验证。与自来水（从浅层地下水位向上抽取的水）不同，土壤水，渗滤和侧向流量随降水增加。Mann Kendall趋势测试还显示，年度和每月土壤含水量（SWC）和渗滤率均无趋势。但是，自来水有减少的趋势（每年1.091毫米）。灌溉水对蒸散量（ET）的贡献从夏季的9％到春季的32％不等。SWC还表现出更高的空间变化。流域的较大部分记录了长期的年平均土壤含水量，范围在0.1至0.2 mm mm之间^-1。土壤水异常（SWA）始终遵循研究区域干旱和潮湿季节的趋势。尽管使用模型得出的干旱监测指标对干旱地区的农民和决策者很重要，但它需要在更大范围内进行密集验证，以提高模型结果的可靠性。