中文摘要：

应用土壤-植被-大气系统水热传输模型CoupModel,在野外定位观测试验的基础上对陕北黄土丘陵沟壑区阴、阳坡荒草地SVAT系统水分传输进行了模拟。结果表明,土壤含水率和土壤温度模拟值与实测值有较高的一致性;阳坡荒草地的土壤蒸发量较阴坡高,阳坡荒草地植被蒸腾量低于阴坡荒草地,说明阴、阳坡荒草地在大气-土壤界面和植被-土壤界面水分交换差异明显;干旱年大气降水主要消耗于土壤蒸发和植被蒸腾,蒸散量超过了同期降水量,输入草地系统的降水满足不了水分的支出,土壤水库处于负补偿状态。丰水年,试验地约有20%降水储存于土壤中,系统的水分收入大于支出。黄土丘陵沟壑区阳坡和阴坡是水热条件不同的立地类型,阳坡用于土壤蒸发的水分较多,土壤储水量低,因此阳坡植被配置应当考虑盖度较高、可以降低土壤蒸发的植被类型。

英文摘要：

In the loess hilly and gully region of northern Shaanxi Province, the CoupModel was used to simulate the water balance of the soil-vegetation-atmosphere in the south- and north-facing slopes of grasslands. The simulation results showed that simulated values of soil water content and soil temperature was generally in good agreement with measured values in the investigated stands, implying that the CoupModel could be successfully applied to demonstrate the complex interactions between hydrological processes in the soil-vegetation-atmosphere system. Soil evaporation in the south-facing slope of grassland was higher than that in the north-facing slope, while vegetation transpiration in the south-facing slope was lower than that in the north-facing slope, indicating that there was a significant difference of water exchanges between the interfaces of atmosphere and soil, and soil and vegetation. In the dry year, vegetation transpiration and soil evaporation were the main components of water consumption in the investigated stands, which was more than the precipitation and water input was lower than water output in the soil reservoir. While in the wet year, 20% of precipitation was recharged and stored in the soil reservoir. This study indicated that water transfer and balance in the south-facing and north-facing slopes was quite different. Since there was high soil evaporation and low water storage in the south-facing slope, it is important to carefully choose planting species during the processes of the sloping land conversion program.