Determining the Spatial Pattern of Rice Cropping Schedules using Time-Series Satellite Imagery of the Red River Delta, Vietnam

要旨

We elucidated characteristics of rice cropping schedules across the Red River Delta (RRD), Vietnam by examining the spatial pattern of rice phenology across the delta using MODIS time-series data for 2003. We applied the Wavelet-based Filter for determining Crop Phenology (WFCP) to assess time changes in Enhanced Vegetation Index (EVI), reflecting the crop status. The results of the analysis were summarized at the district level by compiling cropping-schedule maps. For example, the winter-spring rice in eastern regions was cultivated earlier than that in other regions, rainy season rice in coastal regions was harvested later than that in other regions, and the proportion of the land area planted in off-season crops was smaller in regions in which the rainy season rice was harvested relatively late. Although it has been stated that the most recent rice-cropping system employed in the RRD tends to start late and finish early (i.e., a short cropping duration) due to the introduction of short-period rice varieties and the expansion of the off-season crops, the results of this study revealed that there were diverse variations on the rice cropping schedule including even a traditional cropping schedule (i.e., a longer rice-cropping period) in the RRD.