Rock moisture is rarely deliberated but crucial for hydrologic regulation in semiarid loess hilly regions. In this study, using in-situ monitoring observation and simulation, soil and rock moisture spatiotemporal variations under planting alfalfa and caragana were analyzed and sketched, and the water storage contributions by weathered bedrock layers (WBLs) under different rainwater scenarios were then simulated and estimated. The results showed that WBLs had apparent spatiotemporal changes in water distribution and storage with rainfall events. Under water scarcity scenarios, WBLs increased the variabilities of water storage, with an average increase of 89.9 % in alfalfa and 14.2 % in caragana, providing wider water supply boundaries for vegetation. However, higher volumetric water content was presented under relatively abundant water scenarios. The average soil water content was 0.08 cm cm in alfalfa and 0.09 cm cm in caragana, while the average rock water content was 0.12 cm cm in alfalfa and 0.13 cm cm in caragana. Profile water consumption goes to surface soil evaporation and plant transpiration over an entire growing season, while extrawater would be stored in WBLs to maintain vegetation growth during the water-scarce seasons. Moreover, water storage had a positive linear relationship with the thickness of WBLs. Rock water storage increased by 6.9 % in alfalfa and 3.7 % in caragana after adding 20 cm WBLs, while it increased by 23.6 % in alfalfa and 9.9 % in caragana after adding 50 cm WBLs. Furthermore, various exogenous rainwater simulations showed that differences in water storage were significantly increased with WBLs thickness. This study would provide new insights into the deep-rooted plant distribution planning in semiarid loess hilly regions, and could also be helpful for the rational water resources utilization and management in shallow soil areas.

中文翻译：

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在不同降水情景和植被覆盖度下，岩石湿度增强了地下水储存

岩石湿度很少被考虑，但对于半干旱黄土丘陵地区的水文调节至关重要。本研究利用现场监测观测和模拟，对种植苜蓿和柠条的土壤和岩石水分时空变化进行了分析和勾画，并模拟和估算了不同雨水情景下风化基岩层（WBL）的蓄水贡献。 。结果表明，WBL的水分布和储存量随降雨事件出现明显的时空变化。在缺水情景下，WBL增加了水储存的变异性，苜蓿平均增加了89.9%，柠条平均增加了14.2%，为植被提供了更宽的供水边界。然而，在水资源相对丰富的情况下，却呈现出较高的体积含水量。苜蓿平均土壤含水量为0.08 cm cm，锦鸡儿平均岩石含水量为0.09 cm cm；苜蓿平均岩石含水量为0.12 cm cm，柠条平均岩石含水量为0.13 cm cm。整个生长季节的地表土壤蒸发和植物蒸腾消耗的水量，而多余的水将储存在 WBL 中，以在缺水季节维持植被生长。此外，储水量与WBL的厚度呈正线性关系。添加20 cm WBL后，苜蓿和柠条的岩石蓄水量分别增加了6.9%和3.7%，而添加50 cm WBL后，苜蓿和柠条的岩石蓄水量分别增加了23.6%和9.9%。此外，各种外源雨水模拟表明，储水量的差异随着 WBL 厚度的增加而显着增加。本研究将为半干旱黄土丘陵区深根植物分布规划提供新的见解，也有助于浅土地区水资源的合理利用和管理。