Research On Horqin Sand Ground Desertification Evaluation At The Beginning Of 21^st Century Based On 3S Techniques

Land desertification evaluation technology study is one of the key contents of desertification study area. To conduct timely evaluation and monitoring on the desertification process and master the dynamic and mechanism of desertification occurrence and accurately evaluate the degree of desertification on time is the basis of constructing desertification forecasting system. At the same time it can provide scientific evidence for national and regional reasonable layout and decision of desertification prevention project.The key technique of desertification remote sensing monitoring is extracting desertification information from remote sensing images.In combination with field investigation,take sample of ground positioning, and search the desertification information extraction method on the basis of research of preceding. And to quantitatively evaluate 21 century KEERQIN desert desertification condition and it's dynamic trend and point out the existing problem and it's improvement policy in the process of desertification treatment.This study's main information sources are the original image of KEERQIN ZUOYIHOUQI TM,ETM+ image in 2000 and 2007.By means of band combination, calculate the vegetation index and at the same time compared the vegetation coverage result on the basis of NDVI,SMAVI. After comparison it is found out that vegetation coverage based on the SMAVI is more practical and scientific for the actual investigation condition of KEERQIN ZUOYIHOUQI compared with the vegetation coverage based on the NDVI. On the basis of evaluation of desertification grades to the vegetation coverage of KEERQIN ZUOYIHOUQI, and in combination with soil brightness index and soil wetness index for the three evaluation index, and make use of remote sensing decision tree classification method to classify the desertification of KEERQIN ZUOYIHOUQI to three kinds of desertification.Monitoring result shows that total desertification area of KEERQIN ZUOYIHOUQI in 2007 is 5660.14 km~2and accounts for 49.02% of the total land area. Among them heavy desertification land area is 3276.79km~2 and accounts for 49.02% of total desertification land area; Light and medium desertification land area is 1569.83km~2and 813.5181km~2 respectively and accounts for 27.73% and 14.37% of the total desertification area. Not desertification land area is 5822.02km~2 and accounts for the 50.42% of the total land area. Result of decision tree classification shows that area of wind erosion desertification is 5336.87 in desertification types in 2007, and accounts for 94.29% of land desertification area.Salty desertification and water erosion desertification land area is 276.42km~2 and 46.85km respectively and accounts for 4.88% and 0.83% Of the desertification land area.From the 21 century's beginning dynamic changes, in recent8 years KEERQIN ZUOYIHOUQI total land desertification area reduced 567.03km~2,reduced 70.87 km~2 annually从degree of desertification stabilized basically and reduced. Desertification land area reduced to 49.02% in 2007 from 53.93% in 2000 in total land area. Light and medium desertification land area reduced, land area of light desertification land area reduced 2188.22km~2 and medium desertification land area reduced 424.93km~2. Heavy desertification and not desertification land area increased and heavy desertification land area increased 2046.13km~2 and not desertification land area increased 587.25km~2。From the point of desertification types, change of wind erosion desertification land area is the biggest. It reduced from 5852.76km~2 in 2000 to 5336.87km~2 in 2007 by 8.81%。Water erosion desertification increased from 12.23 km~2 in 2000 to 46.85 km~2 in 2007. salty desertification reduced from 362.17km~2 in 2000 to 362.17km~2 in 2007 by 23.68% From the characteristic of land desertification spatial distribution changes, the desertification stable area mainly distributes in the western and middle part of this banner. In converse area mainly distributes in the eastern and southern area. Desertification developing area mainly distributes in the north and northwestern area.The driving force basic factor of 21 century beginning's land desertification changes is the natural factor such as composition material of land surface and climate condition. Human factor had dominant functions. People took many kinds of treatment measures. These measures at the desertification severe disadvantageous condition such as the climate warming and reduction of rainfall and increasing of evaporation still make the KEERQIN sand area stable basically and developing towards the desertification reduction.