Even after the winds have subsided, the flooding potential from storms can remain for several days. Nearly 60% of the deaths due to hurricane flooding have been from drownings related to inland heavy rain events. The graph shown is called a hydrograph. Hydrologists, a person that studies water and its interaction with the Earth, use hydrographs to monitor the discharge of a river at a particular fixed point with respect to time. Discharge is the volume of water flowing past a location per unit time (usually in cubic feet per second (cfs)).
These hydrographs are from some of the major rivers that experience unprecedented flooding. The extensive amount of rainfall from Hurricane Florence caused the rapid rise of river systems across portions of the Southeast, creating disastrous flooding in areas that were inland from the coast.
Source: weather.gov
The color code helps identify the intensity of flooding or potential flooding along the river: