Abstract
There are few studies on the estimation the spatial distribution of rice-planting time. In this study, we tried to develop the methods to estimate the rice-planting time with multi-temporal RADARSAT data. And by using the distribution map of the rice-planting time, we investigated the relationship between the rice-planting time and the environmental factors (soil and temperature) spatially in the middle and upper areas of Ishikari Basin. The rice-planting time was quantified by analyzing the time series water status of paddy field. And it was also possible to estimate the total planted area for each district with estimation errors ranging from -11.5％～+25.7％. The root mean square error (RMSE) of the estimation was 1.5 km2. By making the distribution map of the rice-planting time and comparing it with the distribution map of the referential environmental factors, which are soil type and average temperature, it was not confirmed that there is no spatial relationship between the distribution of average temperature and that of rice-planting time. Additionally, it was noted that the paddy fields where the soil type is gley soil or peat soil tend to be planted later than that where the other soil are distributed.
