To investigate the evolution of a disastrous oil spill from the Hebei Spirit accident, oil slicks were identified from SAR images using a neural network and
an adaptive threshold method.

The results from the two objective methods showed good agreement, which was enough for the estimation of the extent of oil patches and their
trajectories.

Quantitative analyses showed that the detected oil slicks moved southward, corresponding to the prevailing wind and the tidal currents, and gradually
dissipated during the spill, except for an extraordinary rapid decrease in onshore regions at the initial stage.

The initial dissipation of the spilled oil was induced by tidal mixing in the tidal front zone. The spatial and temporal variations of the oil slicks confirmed
the influence of atmospheric and oceanic environmental factors.