In this study, the impact of gravel was taken into account in the regional climate model version 4.7, which was driven by the ERA-Interim with a resolution of 1.5 km in this numerical experiment. The gravel parameterization schemes and the original soil hydrothermal parameterization schemes were used in the regional soil hydrothermal simulations on the Tibetan Plateau (TP), respectively. The performance of the two schemes in simulating the soil moisture (SM) was assessed. Moreover, three areas were selected in terms of the distribution of gravel content on the TP to investigate the differences in the internal mechanism of the model between the two schemes. The performance of the gravel schemes in simulating SM is generally improved compared with that of the original schemes. The simulation effect is superior in the southeastern TP. Except for the southeastern TP, the performance in simulating the temporal variations of SM below the soil depth of 1.0 m still needs to be improved. The fractional saturated area (f_sat) and the fraction of the inundated area (f_h2osfc) are two pivotal variables that control the important component of the hydrologic process. There may be a threshold for the increase of f_h2osfc, when the increase of f_h2osfc is lower than this value, the main effect of increasing f_h2osfc is to reduce the surface moisture that is, divided into the input of soil. However, when the increase of f_h2osfc is higher than this value, the main effect of increasing f_h2osfc is to increase the bottom drainage from the surface water store. The increasing gravel content will induce the decreasing mineral soil saturated hydraulic conductivity, which leads to SM increases, the opposite is true.

中文翻译：

---

基于RegCM4的青藏高原砾石参数化方案及其区域评价

在本研究中，由 ERA-Interim 驱动的区域气候模型 4.7 版考虑了砾石的影响，该数值实验中分辨率为 1.5 公里。砾石参数化方案和原始土壤热液参数化方案分别用于青藏高原（TP）区域土壤热液模拟。评估了两种方案在模拟土壤水分 (SM) 方面的性能。此外，还选取了TP上砾石含量分布的三个区域，研究了两种方案之间模型内在机制的差异。砾石方案在模拟 SM 中的性能与原始方案相比普遍提高。青藏高原东南部模拟效果较好。除青藏高原东南部外，模拟1.0 m以下土壤深度SM时间变化的性能仍有待提高。分数饱和区域（f _sat ) 和淹没面积的比例 ( f _h2osfc ) 是控制水文过程重要组成部分的两个关键变量。可以有用于增加的阈值˚F _h2osfc，当增加˚F _h2osfc是低于此值，增加的主要作用˚F _h2osfc是降低表面水分即，分为土壤的输入端。但是，当f _h2osfc的增加高于该值时，增加f _h2osfc的主效应是增加地表水库的底部排水。砾石含量的增加会引起矿质土壤饱和导水率的降低，从而导致SM增加，反之亦然。