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土壤导热率是土壤的基本物理参数之一,也是陆面模式的重要输入量,对研究土壤热传输、水热耦合运移有重要意义。青藏高原由于独特的地理环境备受学者关注,但目前常用的土壤水、热属性参数化方案仅仅考虑了沙土、粉土和黏土,就砂砾石重要性的认识还不足,很少有模式模拟砾石对青藏高原多年冻土和高寒草地的影响。采用便携式热导仪(KD2 Pro,DECAGON,美国)测量了青藏高原玛多和北麓河两地典型土壤在冻结和未冻结状态下不同水分条件时的土壤导热率,分析了砂砾石含量对土壤孔隙度的影响及冻结和未冻结状态下,不同水分条件下砂砾石含量对土壤导热率的影响。结果表明:当含水量高于某一阈值时,含水土壤冻结状态下的导热率高于未冻结状态下的导热率;土壤含水量对土壤导热率影响显著,导热率随着含水量的增加而增大,在含水量较小时变化更明显;砂砾石含量比重多的土壤孔隙度较小,且砂砾石含量越大的土壤在冻结状态下导热率高。以上结果表明,砂砾石对土壤导热率有显著影响,在将来的模式模拟研究中必须考虑砂砾石对土壤热属性的影响,进而提高土壤水热过程模拟的精度。
Soil thermal conductivity is one of the basic physical parameters of soil and is also an important input of land surface model. It is of great significance to study soil heat transfer, water-heat coupling and migration. Due to its unique geographical environment, the Qinghai-Tibet Plateau has drawn much attention from scholars. However, the common parameters of soil water and heat properties currently only consider sandy soil, silt and clay. The understanding of the importance of gravel is not enough. Influence of Qinghai - Tibet Plateau Permafrost and Alpine Grassland. Soil thermal conductivity of typical soils of Maduo and Beilu Lu of Qinghai-Tibet Plateau under different moisture conditions was measured by portable thermal conductivity meter (KD2 Pro, DECAGON, USA). The effects of sand-gravel content on soil Porosity and influence of sand and gravel content on soil thermal conductivity under different water conditions under freezing and unfrozen conditions. The results show that when the water content is higher than a certain threshold, the thermal conductivity of water-containing soil in frozen state is higher than that in unfrozen state. The soil moisture content has a significant effect on soil thermal conductivity. With the increase of water content And the change is more obvious when the water content is smaller. The soil with more sand and gravel content has smaller porosity and the soil with larger sand and gravel content has higher thermal conductivity under freezing condition. The above results show that gravel has a significant impact on soil thermal conductivity. In the future model simulations, the influence of gravel on soil thermal properties must be considered, and then the accuracy of soil hydrothermal process simulation can be improved.