Knowledge of spatiotemporal dynamics of soil water storage (SWS) is essential for hydrological modeling and vegetation restoration in semi-arid areas. However, characterizing the temporal stability of SWS at a regional-scale requires time-consuming and labor-intensive manual sampling. Moreover, the influence of soil depth on temporal stability of SWS is not systematic. This study aimed to investigate the influences of sampling frequency and soil depth on SWS and SWS temporal stability. We measured soil moisture at 20-cm intervals in the soil profiles to a depth of 3 m using a neutron probe at 135 locations along a 1340-m long transect on 14 dates from 2012 to 2013. Results showed that sampling frequency did not influence the mean SWS (P < 0.05), while sampling frequency significantly affected temporal stability characteristics including Spearman’s rank correlation coefficient (r_s), standard deviation of mean relative difference (SDRD), the number of locations with SDRD < 5%, and the representative locations. Temporal stability of SWS increased with the increasing soil thickness and depth, which increases the possibility of the number of representative locations in deep soil. Although the mean SWSs of all soil depths can be predicted accurately at each sampling frequency, the prediction accuracy improved when sampling frequency was reducing. The values of R² ranged from 0.769 to 0.978 at 15-day sampling frequency, and from 0.987 to 0.998 at 45-day sampling frequency. Soil moisture stability may be more important than the soil water regime during prediction of soil moisture. These findings can provide guidelines for optimizing soil moisture sampling strategies and benefit management of water resources in semi-arid watershed.

了解土壤蓄水（SWS）的时空动态对于半干旱地区的水文建模和植被恢复至关重要。然而，在区域范围内表征 SWS 的时间稳定性需要耗时且劳动密集型的手动采样。此外，土壤深度对 SWS 时间稳定性的影响不是系统的。本研究旨在探讨采样频率和土壤深度对 SWS 和 SWS 时间稳定性的影响。从 2012 年到 2013 年的 14 个日期，我们使用中子探针在 1340 米长的样带上的 135 个位置测量了土壤剖面中 20 厘米间隔的土壤水分，深度为 3 米。结果表明，采样频率不会影响土壤湿度。平均 SWS ( P < 0.05)，而采样频率显着影响时间稳定性特征，包括 Spearman 秩相关系数 ( r _s )、平均相对差的标准差 (SDRD)、SDRD < 5% 的位置数量和代表性位置。SWS的时间稳定性随着土壤厚度和深度的增加而增加，这增加了深层土壤中代表性位置数量的可能性。虽然可以在每个采样频率下准确预测所有土壤深度的平均 SWS，但随着采样频率的降低，预测精度会提高。R ²的值在 15 天的采样频率下为 0.769 至 0.978，在 45 天的采样频率下为 0.987 至 0.998。在预测土壤水分时，土壤水分稳定性可能比土壤水分状况更重要。这些发现可以为优化土壤水分采样策略和有利于半干旱流域水资源管理提供指导。