section_path: Topography/The flow of rivers/Subterranean rivers
section_name: Subterranean rivers
paragraph_text: Subterranean rivers
  
  Subterranean rivers may flow underground through flooded caves. This can happen in karst systems, where rock dissolves to form caves. These rivers provide a habitat for diverse microorganisms and have become an important target of study by microbiologists. Other rivers and streams have been covered over or converted to run in tunnels due to human development. These rivers do not typically host any life, and are often used only for stormwater or flood control. One such example is the Sunswick Creek in New York City, which was covered in the 1800s and now exists only as a sewer-like pipe.