Study on Change Rules and Influencing Factors of Soil Moisture in Huaibei Plain

[Objectives] To study the relationship between soil water, groundwater burial depth, and precipitation for summer maize in Huaibei Plain. [Methods] The atmospheric precipitation, soil water and groundwater for the growth period of summer maize in Huaibei Plain were analyzed using the 26-year long series of data from the Wudaogou Hydrological Experimental Station, combined with the hydrogen and oxygen stable isotope tracing method. [Results] The average soil moisture content of summer maize in different growth periods showed a trend of first decreasing, then increasing and then decreasing with the increase of soil depth.The average soil moisture content was the lowest at the surface soil layer.From the characteristic values of hydrogen and oxygen isotopes of atmospheric precipitation, soil water and groundwater, it can be known that the average values of δ18O and δD of soil water decreased with the increase of soil depth, indicating that soil moisture evaporation leads to the enrichment of soil heavy isotopes, and the degree of enrichment decreased from the surface layer to the deep layer of the soil. The seasonal variation of the stable isotope of hydrogen and oxygen in soil water declined with the increase of soil depth. The soil water changes at 30 cm and 50 cm soil depths were the most obvious. The soil was easily recharged by precipitation, and soil evaporation was relatively strong. [Conclusions] The research results are favorable for in-depth understanding of the regional water cycle process, and are expected to provide a certain scientific basis for realizing the efficient and sustainable use of regional groundwater.