Development of a method to estimate spatio-temporal distribution of paddy field in the Heilongjiang Province of China using MODIS data

Abstract

For the purpose of obtaining information about recent changes of distribution of paddy field in the Heilongjiang Province of China, a method to estimate the area of paddy field in spatially wide range using MODIS data was developed. Land cover condition of the site exhibit characteristically as the mixture with paddy field inundated by water and upland field exposed by bare soil as well as vegetation of perennial trees during the first of June, when rice was transplanted just before the period for the whole part of Province. Based on this feature, two indices derived from MODIS data, NDVI (Normalized Difference Vegetation Index) calculated by using the reflectance of Band 1 and Band 2 and NDBSI (Normalized Difference Bare Soil Index) by Band 1 and Band 7, were introduced. The allocation in the two dimensional scattergram of NDVI and NDBSI showed evidential relation with the fractional area of paddy field per pixel, thereafter, the relation was formulated by introducing integrated indicator obtained from the scattergram. The estimated acreage showed high correlation with the area obtained from Landsat data in condition that the amount was assembled by administrative unit of County. The scattergram produced for different years exhibited the similar features, therefore, the same scheme could be adopted to estimate for continuous years. The method mentioned above estimated the distribution of paddy field in the Heilongjiang Province for the period from 2003 to 2007. The results successfully indicated the substantial increase of area of paddy field in the Sanjiang Plain located in the eastern part of the Province for 2006 and 2007, which could supplement the lack of statistical information.