中国秸秆焚烧的遥感监测与分析

用最近四年的MODIS火点数据,通过相关处理和分析,得出了全国秸秆焚烧状况的时空分布规律。结果表明,秸秆焚烧最严重的区域一直分布在淮河流域和陕西关中平原,这是秸秆禁烧工作的重点;南部各省秸秆焚烧点密度较小,比较分散,造成的危害相对较小。秸秆焚烧的主要时间,北方集中在夏秋季节,主要是小麦、玉米、油菜等的秸秆;南方集中在冬春季节,主要是水稻、甘蔗、油菜等的秸秆。秸秆焚烧的时空分布规律在最近几年基本无大的变化,秸秆焚烧面积在2002年~2005年期间逐年上升。文章结论反映了各地执行秸秆禁烧政策的效果,可为相关政府部门进行秸秆禁烧工作提供依据。

Evaluation of the Agricultural Residues Burning Reduction in China Using MODIS Fire Product

Agricultural residues are materials left over from the production of crops,which include the straw(or stalks) of rice,wheat,maize,sugarcane,and cereal straws etc.The total amount of agricultural residues in China is about 660 million tons every year,while one third remains unused and mostly burnt directly in the field.The burning of straw produces an amount of carbon dioxide and smoke,which concerns over the adverse health and environment effect.The Agricultural Residues Burning Reduction Act,to prevent the farmers from burning of straw in open-air field which adjacent to the main lines of transportation and other important region,has been passed in China several years ago,while the act is not implemented effectively in some district.Remote Sensing data from the meteorological satellite were used to monitoring the open-air field burning of agricultural residues by the State Environmental Protection Administration of China in 2004 year.The fire locations are delivered to local administration and then action are taken to prevent the straw burning.Valuable information was acquired about the status of straw burning in China.The re-visit period of meteorological satellite is not very short,and the data of meteorological satellite is not very effective to monitoring the straw burning,so the status of straw burning in China is not abundant yet.The MODIS fire product is widely used in the biomass fires and other thermal anomalies monitoring currently.The current Collection 4 version of MODIS fire product has good consistency in the temporal dimension.This paper demonstrates the evaluation of Burning Reduction in China using MODIS fire product.Fire pixel location data from 2002 to 2005 years were collected from the MODIS Web Fire Mapper,the number of the fire pixels in China is 162378.These data were identified with land-use map and administration boundary map in the geography information system.Then the fire pixel in the till field were sought out,and the open-field burning of agricultural residues in every province was evaluated.To display the spatial distribution of fire pixel attributed to the agricultural residues burning clearly,point density analysis then is used to calculate density of the fires pixel,and displayed as GRID format.The size of the GRID cell is 10KM*10KM.The fire point density map can display the intensity of agricultural residues burning in the till field,but it is not very effective to calculate its area which agricultural residues burning appeared.The reason is: some burning is missed due to cloud and the small size of fire;the agricultural residues are not always burned completely in a MODIS fire pixel;recurring detection of the burning in the same till field.The characteristic of agricultural residues burning is analyzed,and then this paper presents a simple method to calculate the area of till field,which straw was burned.The number of MODIS fire pixel in the till field of China is 5835,9497,12352,16877,from 2002 to 2005 year,respectively,which is incremental year-by-year.The temporal and spatial distributing of straw burning is also educed.The spatial distributing of straw burning is mapped in pixel density,and the area proportion of till field which Agricultural residues is burned is also mapped in the 10KM*10KM grid.The agricultural residues burning mainly appeared in June and October,when the wheat and maize were harvested,and the till field which straw were burned are mainly located in Jiangsu,An'hui,Henan,Shandong,and Shanxi provinces.The change of the spatial distribution of the agricultural residues burning is not very large in the latest years.