Study On The Dynamic Changes Of Soil Moisture And Salinity In Xingjiadu Yellow River Irrigation Area

With the continuous growth of population and the rapid development of industrial and agricultural economy,the shortage of resources has become an important environmental problem today.The contradiction between supply and demand of water resources is prominent,and the salinization of land is the main factor restricting the development of agriculture.Shandong province is a big agricultural province.At the same time,the total amount of water resources is insufficient.The proportion of agricultural irrigation to the total water consumption in the province is high.The irrigation water conservancy coefficient of the province is less than 0.6.There is still a big gap between the irrigation water conservancy and the irrigation water use coefficient of about 0.8 in the advanced water saving countries.The irrigation method failed to formulate the fine management scheme of agricultural irrigation and the relevant irrigation measures,resulting in great losses of water infiltration in the field.As an important grain producing area in Shandong Province.Based on the background of water saving irrigation,combined with the study on the characteristics of soil water and salt change in the non groundwater mining area in the municipal water conservancy research project of Ji'nan city of Shandong Province,this paper selected the serious soil salinization and no groundwater exploitation area in Xingjiadu irrigation area.Based on field observation,irrigation experiment and laboratory test,the dynamic change characteristics of soil water and salt under different irrigation schemes,different time and different depth were studied by means of mathematical statistics and geostatistical theory.And based on the analysis of soil salinity driving factors,based on the influence factors and mechanism analysis,the relationship between groundwater depth change and soil salinization is studied,and the spatial variability of soil salinity is analyzed,the optimal spatial variability function is simulated,and the spatial distribution of soil salt in the irrigation area is simulated and predicted.The irrigation scheme lays the foundation for rational irrigation scheme,and provides scientific basis for the rational utilization of water resources,the improvement of the regional ecological environment and the realization of the ecological environment safety in the Yellow River irrigated area in the middle and lower reaches of the Yellow River.The main research contents and results are as follows:(1)The characteristics of soil water content migration:Based on irrigation test and field water content determination,considering the growth of crop roots below 60cm and different irrigation schemes,it is more suitable to meet the water requirements of crops when choosing the way of flooding and 52 cubic meters per mu irrigation quota.(2)Study on the influence of soil salinity driving factors:For the influence factors of groundwater depth,the soil salinity increases with the depth of the groundwater.When the groundwater depth is buried 228cm,the salt content of the soil is the highest.When the groundwater depth is 256cm and 282cm,the salt content is the lowest,and the soil salinity is decreasing with the depth of the depth.(3)The dynamic characteristics of soil salinity:After irrigation of one water and two water,the salinity of the upper soil decreased greatly,reaching the standard of non salinized soil,and the salt showed a sign of leaching to the deep layer.After irrigation,the soil salt was increased and kept in the standard range of mild saline soil.Flooding irrigation has a strong inhibition effect on the upward movement of soil salt.Combining with crop yield,irrigation quota is 52m/mu,it not only achieves the effect of water saving,but also ensures the yield of crops.It is more suitable to choose the way of flood irrigation and the irrigation quota for 52m/mu.(4)Spatial variability of soil salinity:Based on Geostatistics theory and Arcgis software simulation,the spatial variation models of soil salt in each layer of 20cm?100cm before irrigation were respectively conformed to spherical model,Gauss model,Gauss model,spherical model,Gauss model,and model parameters analysis of spatial variability caused by structural 40cm and 100cm soil layer The degree is larger.The spatial variation model of soil salinity in each layer after irrigation accords with the spherical model,Gauss model,exponential model,spherical model and Gauss model,and the spatial variability caused by structural factors is strong.The Kriging interpolation method is used to simulate the distribution of soil salt content and adjust the irrigation time and irrigation quota in time,which is of theoretical and practical significance for the fine management of farmland irrigation in Xingjiadu irrigation area.