Study On Time And Space Change And Influencing Factors Of Soil Salinization In Minqin Oasis

The ecosystem of Minqin Oasis is fragile,and the internal land degradation is serious.Soil salinization is one of the important factors that cause land degradation in Minqin Oasis.Since the 1950 s,the ecosystem problem of Minqin Oasis has begun to appear.In order to improve the ecosystem of Minqin Oasis,scholars have begun to study the ecosystem problem of Minqin Oasis.The stability of the Minqin Oasis ecosystem affects people's production and life,and also affects the stability of the ecosystem in the northwestern region.Therefore,the research on soil salinization of Minqin Oasis is very important.With the development of remote sensing technology,remote sensing inversion has gradually become an important method to study soil salinization.The in-depth excavation of soil salinity information on remote sensing images and the study of influencing factors of soil salinity are of great significance for effectively controlling soil salinity and maintaining ecosystem stability.To this end,this paper uses remote sensing imagery as a data source,based on the soil salinity data of 70 samples measured in the field,quantitatively retrieves the soil salinity of the Minqin Oasis,and systematically explores the soil salinity of the Minqin Oasis Time and space changes and influencing factors.The research content includes:(1)Sensitive band selection for soil salinization inversion: This article uses the August 2019 Landsat 8 OLI remote sensing image and Google earth to determine the field sampling points of Minqin Oasis.Extract the spectral reflectance of the soil from the sampling point in the remote sensing image.Soil samples were collected at the sampling sites in the field,and the salt content of the soil samples was determined indoors.Calculate the correlation between soil reflectance and salt content and the spectral diagnostic index to obtain a diagnostic spectrum sensitive to soil salt content: band 1 and band 3;(2)Remote sensing inversion of soil salinity based on multiple linear regression model: This paper establishes a multiple linear regression model based on the soil salt sensitivity diagnostic spectrum as the independent variable and soil salt content as the dependent variable.The accuracy verification results show that for most of the verification samples,the predicted value of soil salt content is very close to the measured value.Through linear fitting,it was found that near the trend line y = 1.0364x+0.0891,the predicted soil salt content of the sample gathered with the measured value,and the determination coefficient was 0.9759,indicating that the remote sensing inversion of soil salt content in Minqin Oasis In other words,the accuracy of the model is higher.(3)Use the obtained model to invert the soil salinity of the Minqin Oasis in 1992,2001,2010 and 2019.The soil salinity of Minqin Oasis was divided into 4 grades according to the classification standard of soil salinity,and ArcGIS 10.2 was used to visualize the soil salinity of Minqin Oasis.The spatial pattern of soil salinization in the study area was analyzed: during each study period,severely salinized land and moderately salinized land were distributed at the edge of the study area,and lightly salinized land and non-salinized land were distributed.In the middle of the study area.From 1992 to 2019,the area of salinized land in Minqin Oasis decreased,and the degree of soil salinity improved.Soil salinization degree Lake area> Quanshan area> Dam area.(4)In the end,the influencing factors of soil salinity in Minqin Oasis were analyzed using hierarchical statistical data,indoor experimental data,and statistical yearbook data.The temperature in Minqin Oasis gradually increased,precipitation was insufficient,and evaporation was strong.The production creates favorable external conditions;the soil salinity increases with the increase of surface water salinity,groundwater salinity,and coarse grains.With the increase of sand grains,fine sand and bulk density in soil,the impact of human activities is the main external cause of changes in soil salinity.