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Université du Xinjiang (2017)

Study on Soil Moisture at Transitional Region between Oasis and Desert Based on Remote Sensing and Hydrological Model in the Weigan-Kuqa River Basin,Xinjiang

杨爱霞;

Titre : Study on Soil Moisture at Transitional Region between Oasis and Desert Based on Remote Sensing and Hydrological Model in the Weigan-Kuqa River Basin,Xinjiang

Auteur : 杨爱霞;

Grade : Doctoral Dissertation 2017

Université : Université du Xinjiang

Résumé partiel
Soil moisture is an important foundation for the exchange of water and energy between the land and atmosphere system.It is also the key link between the surface and groundwater circulation and the carbon cycle in the land.At the same time,soil moisture is one of the most commonly used surface model parameters for estimating the yield of crops,land degradation and drought monitoring,especially has a very important significance on hydrology and meteorology,oasis agriculture,ecological environment and sustainable development in arid region.In present,from the perspective of soil moisture information acquisition method,it can be roughly divided into three categories : ground observation,model simulation and remote sensing monitoring,each one has its advantages and limitations.Therefore,how to integrate the advantages of each soil moisture monitoring method for achieving efficient and high-precision continuous spatial and temporal monitoring of soil moisture is a very hot research topic.Weigan-Kuqa oasis is an oasis of relatively early development in Xinjiang,as it is located in the inland,the climate is hot and dry.In this paper,the Weigan-Kuqa oasis desert transition zone is a typical research target area at arid and semi-arid area.This research combines geostatistics,geographic information system technology and numerical simulation method to study the regional soil moisture characteristics,which from measured to prediction,mechanism to mechanism,and point scale to regional scale.The aim is to obtain accurate estimates of point scale soil moisture as well as regional scales.The main research results are as follows :(1)Based on the spatial variability analysis and correlation analysis of soil moisture and physical and chemical properties and terrain factors in the study area.First,the spatial variation of soil water content show a trend of high in the west and low in the east.In the vertical direction,the soil water content is increased with the depth of the soil profile.From the seasonal changes,soil water content in April was lower than in July.Second,the correlation analysis between topographic factors and soil water content show that there is a significant correlation between terrain humidity index and soil water content.In large-scale soil moisture research,the terrain humidity index is a good substitute index.Third,the importance of variables by random forests show that soil bulk density and soil texture are more important factors on soil water content.Thus,in the future study of the spatial variation of soil water content,it is necessary to consider the effect of soil bulk density and texture on soil water content.(2)Based on TVDI model by optical remote sensing Landsat 8 image,the soil moisture data of the 7th time series from Landsat 8 image are obtained.The soil moisture in April,July and October obtained by remote sensing image inversion compared with the measured soil moisture,the fitting effect is relatively good.The correlation coefficient between the inversion of soil moisture and the measured soil moisture reached about 0.5.Through the construction of the semi empirical model by AIEM model,using the backscattering coefficient obtained by microwave remote sensing Sentinel-1A,can effectively reflect the soil water content in different months of the study area.According to fitting the measured soil moisture data and simulation of soil moisture data,the correlation coefficient R2 reached about 0.8 between them.

Mots clés : Soil moisture content; AIEM Model; TVDI; HYDRUS Model; Ensemble Kalman Filter; Oasis desert transition zone;

Présentation (CNKI)

Page publiée le 14 janvier 2018