Simulation analysis of rainfall-infiltration in humid regions of the eastern China based on field observations:A case study of the Hualong River Basin,Ningbo City
Soil moisture plays a significant role in water infiltration,evapotranspiration,and solute transport in the unsaturated zone,there are remarkable differences in rainfall-infiltration characteristics within different rainfall intensities and different land use types,which is crucial for plant growth and the dynamics of ecosys-tem.In this article,taking the Hualong River,Ningbo City,Zhejiang Province,as an example,combining field in-situ fixed-point observation and model simulation analysis,a soil moisture simulation model HYDRUS-1D was established.And the model was calibrated and verified by using the typical rainfall events on September 29,2016 and October 7,2016.Moreover,a soil water infiltration simulation of different land use types under different rainfall intensities was carried out based on HYDRUS-1D model from 2016 to 2020,to reveal the law of rainfall-infiltration under different land use types in the eastern humid region of China.Results showing that:1)According to the simulation of soil moisture change process,the HYDRUS-1D model has high accuracy in simulating the dynamic change characteristics of soil moisture,and the Nash efficiency coefficient of 90％sim-ulation results is over 0.8;2)Under the same rainfall intensity,the soil infiltration amounts of the four land use types were farmland,waxberry forest,sloping farmland,and bamboo forest in descending order.The infiltra-tion rate was greatly affected by rainfall and rainfall intensity,and the soil infiltration amount increased signi-ficantly with the increase of rainfall intensity under different land uses.3)Soil infiltration is also profoundly af-fected by rainfall duration and previous rainfall.When the rainfall intensity increases one level furtherly,the in-crease in infiltration of each land use type was less than 5％,and maintained a slight increase.And when ex-treme rainfall events occur,the rainfall intensity exceeds the infiltration intensity,resulting the infiltration ex-cess runoff,causing the phenomenon of large rainfall but small infiltration.The research results can provide theoretical reference for agricultural production,three-water transformation law and ecological protection re-search in the humid region of eastern China.
soil moisturerainfallinfiltrationHYDRUS-1D modelthe humid region of the eastern China
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