Flash floods are only a concern for areas near streams and rivers.
FALSE. Flash flooding is caused by heavy rainfall. Flash flood are the most dangerous kinds of floods because they combine the destructive power of floodwaters with incredible speed.
Many times flash floods do occur in and around normally dry creeks or riverbeds and in flowing creeks and rivers. However, intense stationary storms lined up one after the other impacting a certain area can lead to a deluge of rapid moving waters. Think the October 2015 25-inch rainfall in South Carolina.
Flash floods are more and more frequent in areas of high population where the ground cannot absorb the moisture due to abundance of concrete, etc. New York City, Washington/Baltimore, and Philadelphia have seen flash flooding.