Description
Particle track starts from a source point and migrates based on the direction and magnitude of the flow field. This message appears when the track encounters a depression or a sink, such as a well, from where it cannot migrate any farther.
Solution
Check the correctness of the input data to Darcy Flow or Darcy Velocity, from which the input direction and magnitude rasters are created. The depression could either represent a real sink, such as well, or the head data could be bad.