Research Of Regional Cultivated Land Dynamic Change Monitoring Based On MODIS Data

It is necessary to apply high and new technology in dynamic monitoring cultivated land to protect it form reducing besides powerful law method, government administration, economy and planning measure, etc. This paper takes Zhuang Nationality Autonomous Region, Guangxi Province as sample to research cultivated land information remote sensing collection and dynamic monitoring methods by ENVI and ERDAS remote sensing Image Process System on base of the MODIS data collecting on 13 Nov, 2003 and 8 Dec, 2004.In images pre-processing, this paper does not correct precisely the data by geometry method, due the data have already been dealt with primarily. This paper relatively coordinated the remote sensing data by comparing them in the same area in different time instead of collecting data from the ground control point in Guangxi. Optimal Bands Selection, Contrast Enhancement, and Minimum Noise Fraction on base of high spectrum remote sensing images information collecting was used in the images' enhancement contrast enhancement.On the basis of pre-proceeding images, two methods were used in dynamic monitoring Guangxi cultivated land: Post-classification Comparison and threshold of Normalized Difference Vegetation Index (NDVI).(1) Post-classification comparison. It indicates cultivated land changed part by comparing the area-classified results. And it is an effective method to know the dynamic change to cultivated land easily. It is recommended to use this method if great amount of remote sensing images and data exist or seasons are different when collect images.(2) Threshold of NDVI. The threshold value of vegetation area and unvegetaion area can be defined by NDVI. Two phases images can be got through vegetation area classification. The variable area can be fixed through comparison. This method could dynamic monitor cultivated land effectively in the condition that the differences in spectrum character between images are minimum and the vegetation is flourishing. The key skill in using this method is how to determine the threshold according to the histogram of NDVI.The research result from analyzing cultivated land information collected from above methods indicates in 2003 and 2004 cultivated land has reduced 268,900 hectare and 322,800 hectare respectively. Reduced land concentrated in Yao Autonomous County, Du'an in the center of central Gui area, southeast of Liuzhou area, Pingnan area in southeast of Guangxi and Guilin area in northeast of Guangxi. By analyzing data, the reduce mainly results from the drought beginning from 2003 in Guangxi, which was extremely serious in 2004. Drought has leaded thelean land to be unwatered and unable to be cultivated.In addition, this paper also introduced the characteristics of MODIS data, the history and development of remote sensing technologies in land monitoring, and regular remote sensing dynamic monitoring methods, etc.