Estimation of Agricultural Area in Large Irrigation Districts in Yellow River Basin of China using AVHRR Combined with ETM+

For the purpose to detect the change of agricultural area in large irrigation districts in the Yellow River basin, the method to estimate the agricultural area accurately using coarse resolution sensor i.e. AVHRR was developed on the Ningxia irrigation district. The agricultural area was calculated with higher spatial resolution sensor i.e. Landsat ETM+ by land cover classification, and it was correlated with annual maximum NDVT derived from AVHRR in order to get the fraction of agricultural area within one AVHRR pixel. The AVHRR estimation result showed the good agreement with ETM+ calculation in the county based comparison.