 In extreme cases, the overwhelming fall of rain creates mudslides and greatly increases the flow of urban rivers.This sudden influx of water has the potential to flood populated places and drown out wetland habitat; measures have been taken to reduce this potential negative affect while simultaneously restoring the rivers and their watersheds to a pristine and natural state.This regional climate supports a chaparral and woodlands ecoregion that is further divided in three sub-regions where two are observed in San Diego–Tijuana.