Terrestrial water resources originate from atmospheric precipitation and its composition consists of three parts: surface water, groundwater and soil water. For the rain-fed agricultural areas in the semi-arid and semi-humid areas of the Loess Plateau, only surface water and groundwater are considered, and the neglect of soil water is incomplete. The deep loess cover in the Loess Plateau has created a unique condition for the transformation of precipitation water into soil moisture. Studying the change of soil moisture in the Loess Plateau is of great significance to the effective use of water resources and ecological protection. There is a constant moisture exchange between the surface, atmosphere and soil. Soil moisture plays an important role in climate change. It affects the climate through surface evaporation and plant transpiration. At the same time, climate change also directly causes changes in soil moisture. The determination of soil moisture testers found that, especially in the inland Loess Plateau, evaporation from the land surface contributes significantly to precipitation, and evaporation is closely related to soil moisture, especially soil moisture can play a role in small and medium-scale weather processes. Regulatory effect.
The soil moisture in the Loess Plateau of Gansu decreases from southwest to northeast, and there is a dry tongue from north to south in the central part. The drought center is in the northern part of central Guizhou, and the soil water deficit degree differs between the eastern and western sides of Liupan Mountain. The east is slightly better, with a difference of 2% in the same latitude. about. The trend of soil moisture in the seasonal soil water shortage area in the Loess Plateau is obvious, and there is a clear upward trend in the Yuzhong District, while there is a significant downward trend in the Jidong District, and there is no significant trend in other climate regions.
The results of the soil moisture tester show that the characteristics of the multi-year average vertical profiles in different climatic zones are: Poor soil water stability in severely dry areas of soil in northern central Hebei and northeastern Yunnan, with poor coefficient of variation, and severe water shortage in shallow layers. In the spring and late spring and early summer, the deep soil is also in a water-deficient state all year round; the seasonal water shortages in the middle and east Fujian Province are mainly water-deficient in May and June, and the deep soil moisture is relatively good in the eastern part of the Fujian Province. The central area is poor, but the area with low soil moisture is higher in the central area than in the eastern area. There is no obvious water shortage period in the suitable soil moisture area and humid area. The soil moisture in the soil layer above 30 cm is relatively stable, and is transported to the deep layer; soil moisture There are obvious seasonal changes in the relatively low value areas, and there are differences in the time and depth of each climate area.
The soil moisture in the Loess Plateau of Gansu decreases from southwest to northeast, and there is a dry tongue from north to south in the central part. The drought center is in the northern part of central Guizhou, and the soil water deficit degree differs between the eastern and western sides of Liupan Mountain. The east is slightly better, with a difference of 2% in the same latitude. about. The trend of soil moisture in the seasonal soil water shortage area in the Loess Plateau is obvious, and there is a clear upward trend in the Yuzhong District, while there is a significant downward trend in the Jidong District, and there is no significant trend in other climate regions.
The results of the soil moisture tester show that the characteristics of the multi-year average vertical profiles in different climatic zones are: Poor soil water stability in severely dry areas of soil in northern central Hebei and northeastern Yunnan, with poor coefficient of variation, and severe water shortage in shallow layers. In the spring and late spring and early summer, the deep soil is also in a water-deficient state all year round; the seasonal water shortages in the middle and east Fujian Province are mainly water-deficient in May and June, and the deep soil moisture is relatively good in the eastern part of the Fujian Province. The central area is poor, but the area with low soil moisture is higher in the central area than in the eastern area. There is no obvious water shortage period in the suitable soil moisture area and humid area. The soil moisture in the soil layer above 30 cm is relatively stable, and is transported to the deep layer; soil moisture There are obvious seasonal changes in the relatively low value areas, and there are differences in the time and depth of each climate area.
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