The Study Of The Winter Wheat Regional Soil Moisture Of The People's Victory Irrigation District Based On The Coupling Of Remote Sensing And Model

In this paper,the People's Victory Irrigation District is the research area.The surface soil moisture of winter wheat area was obtained by using Landsat 8 remote sensing image and the in situ soil moisture data.Then the linear empirical model and the Biswas deep soil moisture estimation model were established on the basis of analyzing the relationship between surface moisture and deep moisture.The soil moisture spatial variability in the area was analyzed by using the soil moisture content of the entire irrigated area.It provides decision service for irrigation and drought-resistant irrigation in the People's Victory Irrigation District,and provides basis information guarantee for the modernization,informatization and intellectualization of irrigation area.The main results of this thesis are as follows:?1?The suitable TVDI was selected for the surface moisture.The correlation between the three TVDIs?LST-EVI,LST-MSAVI and LST-NDVI?and the soil moisture at different depths was analysed and compared.The estimation model of soil moisture at different depths was constructed based on the three TVDIs.The results show that the three TVDIs can reflect the shallow soil moisture conditions of the research area.But when the soil depth is equal to 40 cm,only the determination coefficient R²between the LST-EVI and the soil moisture is more than 0.3.?2?The suitable depth of the Landsat 8 remote sensing image monitoring study area soil moisture was determined.The relationship between the three TVDIs and the soil moisture/average soil mositure at different depths was studied using the in situ soil moisture at different depths.The results show that the correlation between the three TVDIs and the average soil moisture at different depths is better than the correlation between the three TVDIs and the soil moisture at different depths.At last,it is determined that the soil moisture at depth of 0-20 cm is the appropriate depth of remote sensing monitoring soil moisture.?3?The estimation deep soil moisture model was constructed and the spatial distribution of soil moisture at the deep?root?depth of winter wheat was obtained.The estimation deep soil moisture models were constructed based on the empirical model and Biswas deep soil moisture estimation model and analysed the inversion precision of the two models.The suitable estimation deep soil moisture model was selected.The spatial distribution of soil moisture at the deep?root?depth was obtained and the drought distribution map of the research area was obtained according to relevant research results.?4?The spatial variability of soil moisture in different scales of the study area was analyzed and the spatial variation law of soil moisture in the study area was obtained.The variation coefficient of small scale?S30₁,S30₂,S30₃?increases with the increase of the research amplitude.However the variation coefficient of the whole study area?L90,L250,L1000?and the corresponding ratio of spatial heterogeneity are almost constant,which means that the sampling interval has little effect on the spatial variability of soil moisture in the whole study area.Therefore,the high spatial resolution remote sensing image can be replaced by low spatial resolution remote sensing image in order to improve the temporal resolution of remote sensing image.The purpose of monitoring soil moisture daily in the studied area would be realized.