Soil Moisture Dynamics and the Response to Precipitation in Fixed Sand Dunes of Artemisia Ordosica Community in Mu Us Sandy Land

In order to deeply study the response of soil moisture to precipitation, the characteristics of precipitation infiltration and the recharge of precipitation to soil moisture in the fixed sand dunes of Artemisia Ordosica in Mu Us sandy land, this study used the AR-5 automatic soil moisture monitoring system and AV-3665R rainfall sensor to conduct long-term and continuous monitoring of soil moisture and precipitation in the fixed sand dunes of Artemisia Ordosica, and fitted the precipitation infiltration through the multi-compartment model. The results show that: (1) The accumulated precipitation in the growing season in the study area is 332.75 mm, which has a significant impact on the soil water content of 0-120 cm soil layer. The precipitation before August only affects 80 cm and above; The precipitation from August to October has a significant impact on the soil water content of 0-120cm soil layer. (2) After each precipitation event, the soil water content of 0-60 cm layer in various fields will change significantly. After each precipitation, the maximum water content of surface soil is significantly higher than that of deep soil. Since the initial soil water content before the second precipitation is significantly different, the maximum soil water content after the second precipitation is significantly higher than that after the first precipitation. The initial soil water content has a significant impact on infiltration and redistribution, which will make a significant difference between the migration rate of the wetting front and the maximum soil water content after precipitation. (3) The multi-compartment model is used to simulate the infiltration of precipitation, and the parameters are modified after the preliminary validation of the model. The results show that the modified model parameters meet the set value range, and the goodness of fit meets the statistical requirements. The modified model can better reflect the infiltration of different precipitation, different precipitation intensity, and different areas. According to the different range of parameters in the improved model, it can express the relationship between plants and soil moisture under different precipitation conditions and different time periods.