Measurement Of Soil Water And Salt Transport Along The West Main Canal In Ningxia And Numerical Simulation With Lattice Boltzmann Method

Soil doesn't only play a very important role in the ecological environment,but also is an indispensable part in human survival's development and the production activities.However,on the one hand,with the development and advancement of industry and agriculture,the emissions of“three wastes” in industry and the excessive use of pesticides and fertilizers in agriculture cause water and soil pollution.On the other hand,with the continuous increase of population,over exploitation of soil and groundwater and climate change lead to the gradual reduction and degradation of soil fertility and the emergence of salinization.Therefore,it has certain application value to study water and salt movement in soil.This study conducts the field survey and the contrast analysis along the West Main Canal in Ningxia,the numerical simulation research on the water and salt migration in soil is performed by using the D2Q9 lattice Boltzmann mathematical model.The main contents of the thesis are as follows:Firstly,the basic theory of lattice Boltzmann method is introduced,and the common boundary condition processing format is explained.Secondly,aiming at the soil salinization along the West Main Canal in Ningxia,82 representative sample points are selected and the eight major ions and p H values of 164 soil samples in the study area is measured.The distribution characteristics of salt content in soil and p H value are carried out by correlation analysis and principal component analysis and the the distribution of salt content in soil and p H value is explored.The spatial distribution of total salt content in soil in the study area is obtained by two-dimensional interpolation.Then,the D2Q9 soil micro seepage model is established,and the influencing factors of different porosity,different size of particles and different soil structure on soil seepage are compared and analyzed.And the D2Q9 soil macro seepage model is established to verify the effectiveness and stability of the model.Finally,aiming at the solute transport in soil,the coupling model of D2Q9 double distributed incompressible lattice Boltzmann is established,in which the soil is regarded as a porous medium.The porous media is constructed by using square parallel structures,square staggered structures,circular parallel structures and circular staggered structures.The influence of different structures,different Reynolds numbers,and different initial seepage velocity on soil solute transport is explored.