Entries in geomorphology (1)


When dynamic equilibrium loses its equilibrium

I attended a workshop on stream erosion.  Stream systems are customarily understood to be in a state of dynamic equilibrium.  Many historical maps and aerial photos show traces of former channels that have been abandoned over and again.  Today’s stream channel is temporary and dynamic.  As long as rainfall, runoff, sediment load, etc. remain fairly constant, then the system will find its own point of equilibrium- hence ‘dynamic equilibrium.’  Changing rainfall patterns, paving the soil etc. changes the system, throwing the equilibrium into a wobble.  Many streams are now unstable and seeking a stable configuration.  The result is erosion, flooding, sedimentation- often at significant costs.  So the workshop is important and the message is crucial.