Study On The Spatial Variability Of Soil In Saliferous Irrigation Districts And Simulation Of Sater And Salt Based On HYDRUS

In the background of the significant reduction of the water diversion from Yellow River in Hetao irrigation district,the study of soil spatial variability and water and salt simulation of Hetao irrigation district have great significance in all aspects such as the economic development of industry and agriculture,water resources utilization and ecological environment.In this thesis,the spatial variability of soil particle composition,water content,EC value and spatial variability of organic matter content were analyzed by using the two scales of Yongji irrigation area and Longsheng experimental areas in Hetao irrigation district.The soil water and salt migration model was used to simulate theprocess of the soil water and salt migration;it could give a forecast and a better control mode by obtaining the general law of different soil water and salt migration.And it is possible to lay a solid theoretical basis for the water-saving irrigation and water and soil environment simulation evaluation in the irrigation area,.and provide a scientific basisfor the development of water-saving programs,irrigation management decision-making.The results show that the coefficient of variation of each scale is between 15.56%and 133.05%,and the clay content of 40?60cm soil layer and 0?100cm of Longsheng research area are strong variability,the others are moderate variability.At the same scale,the spatial variability of soil clay content,silt content and organic matter content increased with the depth of soil layer,and the sand content,water content and EC value were opposite.On the same depth,The spatial variability of water moisture content and organic matter content is larger than that of Longsheng research area.The results of geostatistics statistical method shows that the silt content and sand content of 20?40cm soil layer in Yongji watershed are not related.The content of clay,silt and sand,the content of water and the content of organic matter in the soils of Yongji irrigation area have strong spatial correlation and medium spatial correlation.The soil EC value has a strong spatial correlation in the Longsheng research area,and there is a weak spatial correlation in the Yongji irrigation area,and the 40?60cm soil layer has no spatial correlation.The spatial correlation distance of each scale increases with the increase of the research scale.The analysis of multiple fractal method shows that each indicator has obvious multi-fractal characteristics in different soil layers at different scales.The spatial distribution of soil clay content in 40?60cm soil layer is mainly based on small numerical data,and other soil layers are opposite.The spatial distribution of soil silt and sand content in two different soil layers is dominated by large numerical data.The water content in 0?20cm,20?40cm,40?60cm and 80?100cm soil layer in Yongji irrigation area and 0?20cm and 20?40cm soil layers in Longsheng research area is dominated by large numerical data,while other soils are opposite.The EC values in the Longsheng research area scale of 80?100cm soil layer and Yongji irrigation area of 20?40cm soil layer of the spatial distribution of large numerical data,while other soil layers are opposite.The spatial distribution of 0?20cm,20?40cm and 80?100cm soil layers in the Longsheng research area is mainly based on the numerical data,and the soil layers in the other soil layers and Yongji irrigation area are the opposite.The numerical simulation results show that the suitable irrigation amount of sandy loam is 300 mm in maize growth period and 150mm in autumn pouring period.The suitable irrigation amount of silt loam is 330 mm in maize growth period and 180mm in autumn pouring period.The suitable irrigation amount of silt in the growth period of corn is 360mm and 210mm in autumn pouring period.