| The degree of desertification and soil moisture is an important factor to reflect the environmental evolution of desertified land environment.it is also an important index to monitor land degradation.it is also the main parameter in climate and environment,ecological condition and agricultural production.it determines the occurrence and evolution of land desertification on regional,and productivity of agriculture and animal husbandry and so on.TVDILandsat of 30m spatial resolution inversed by Landsat8/ETM+was used to deduce TVDIMODIS of 1km spatial resolution inversed by MODIS using the spatial scale deduction method,so that the spatial resolution of TVDIMODIS increased to 30m,and with the use of MODIS data alone monitoring 0-30cm depth of water content and field moisture content of the measured data for comparative analysis,finally verificate the performance of multi-scale remote sensing model with construct by spatial scale deduction method.Considering the influence of land desertification degree and surface energy and water balance to soil moisture,try to combine the desertification difference index with TVDI to monitor soil moisture content of the depth of 0?30cm and carry out its monitoring precision.The main contents and conclusions are as follows:(1)The overall degree of desertification showed a first increase and a downward trend,the overall degree of desertification in the region has been improved in 2006?2016.(2)The effect of SWEPDI method and energy index method on soil moisture content monitoring fluctuates with time,and the stability of soil moisture content monitoring by TVDI method is relatively good.At the same time,TVDI method is superior to SWEPDI method and energy index method in monitoring soil moisture content,while energy index method is slightly better than SWEPDI method.The linear model has better fitting effect than the exponential and logarithmic models,and the linear model has the characteristics of simple and practical and good overall stability.The linear model of TVDI is used to determine the fitting function chosen for this study.(3)The degree of fitting of the relative moisture content inversed by remote sensing shows an overall decrease with the increase of the soil depth(0?10cm,0?20cm,0?30cm),while the average relative error increases with the depth of the soil The results show that the monitoring accuracy of soil moisture content is 0?10cm is superior to the soil moisture content of 0?20cm and 0?30cm soil layer,but the difference is not very different.At the same time,taking 0-3 0cm soil layer as the best remote sensing monitoring depth,taking into account the depth of remote sensing satellite exploration,the actual soil sampling and the soil water characteristics and the soil water use characteristics of sand dune vegetation.(4)Landsat8/ETM + Inversion of 30m spatial resolution TVDILandsat combined with multi-scale remote sensing model to the MODIS inversion 1km spatial resolution TVDIMODIS spatial scale deduction,the two high-resolution,multi-temporal advantages effectively combined,making MODIS inversion The spatial resolution of TVDI is improved and the scale effect is improved.The precision of water depth monitoring in 0?3 0cm soil layer is improved,and the high time and spatial resolution TVDI data retrieved by MODIS data are obtained,and the regional soil with high frequency is finally realized Dynamic monitoring of drought conditions.(5)TVDILandsat of 30m spatial resolution in versed by Landsat8/ETM+ was used to deduce TVDIMODISs of 1km spatial resolution inversed by MODIS using the spatial scale.deduction method,the combination of the advantages of the two effectively,to make the spatial resolution of TVDI inversed MODIS is improved,The monitoring accuracy of soil moisture content is improved,and the TVDI data of high time and spatial resolution retrieved by MODIS data are obtained,and the regional soil with high frequency is finally realized dynamic monitoring of drought conditions.(6)The degree of desertification increased,the surface coverage decreased,the surface energy and water balance change,can lead to changes in soil moisture.TVDI and DDI binary regression model monitoring soil moisture content of the depth of 0?30cm is better than the individual TVDI model,can more accurately monitor the distribution of drought in Wushenqi county. |
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