A phenology-based approach to map crop types in the San Joaquin Valley, California

An accurate and timely crop-type map is essential in water planning in California. So far, no effort has been made to effectively and efficiently identify specific crop types on an annual basis in this area. We have explored the potential of Moderate Resolution Imaging Spectroradiometer (MODIS) reflectance images to annually map major crop types in the San Joaquin Valley, California. A phenology-based classification approach has been employed, which has extracted phenological metrics from normalized difference vegetation index (NDVI) profiles and identified crop types based on these metrics using decision trees. According to a comparison with traditional maximum-likelihood classification, this phenology-based approach has shown great advantages when the size of the training set was limited by ground-truth availability and when the central tendency was absent in agricultural systems heavily influenced by human activities.