When rivers crest, they are at their highest level possible during a flooding event. It is a normal part of a flood, but a little difficult to understand without the help of an expert.
The definition of crest in hydrology is the expected or measured high water level before the water begins to recede at a specific location during a storm, hurricane or snow melt. A crest is also the highest point of a lake or river that has been reached within a certain amount of time.
Understanding what these terms mean can be confusing especially for students who are just starting to learn the basics of hydrology and flooding. To make things easier for students and the general public, Rita Lee, the engineering studies section chief at the Illinois Department of Natural Resources, has put together an easy-to-understand explanation of some of the more confusing terms in hydrology.
CFS: Cubic feet per second, or the volume of water flowing in a lake or river.
Datum point: A datum point is a fixed reference point established by the USGS or National Weather Service.
Crests are the highest point a river or lake will reach in a certain amount of time and it is usually limited to floods. It is often the most difficult term to understand because of how varying the depth of a river and lake bottom can be, but it is important for students to know the basic definition in order to better comprehend flooding.