The Monitoring for cropping index of arable land in northwest region using SPOTNDVI-A case of Shaanxi Province

Cropping index is a very important information of agriculture.Monitoring the distribution and changes of it accurately in China is useful to exploit the potential of land climatic resources,as well as reflect great significance to estimation of total grain production accurately.The SPOT-VEGETATION ten days NDVI data from January in 2000 to December in 2007 was used,combined with the 1∶ 250000 land-use maps of Shaanxi Province,we desiged a VC program using differential algorithm to monitor the cropping index of Shaanxi Province's cities and counties from 2000 to 2007.The results showed the cropping index is so different among the different districts.In the ares both along the Great Wall in Northwest China Loess Plateau and northern hilly the cropping index are less than 100%.The indexes for the most of areas in southern area of Shaanbei's Loess and Guanzhong Plain have reached 100%-150%.The indexes of Qinling mountains and the Hanzhong Basin,Bashan Mountains is greater than 150%.From the above saying we can get the conclusion that the crops were matured twice or once annual in Shaanxi Province.The cropping index of all the regions have increased since eight years ago,but every area also exists index lowered areas.The index changes of Hilly area in northern Shaanxi,Guanzhong region and Hanzhong basin are highly relate to the spatial pattern and terrain.Generally speaking,the cropping index of hilly area in northern Shaanxi,Qinling and Bashan mountains change greatly,the index changes of GuanzhongHanzhong Plain increase greatly.