U.S. National Advanced Hydrologic Prediction Service
Information such as the flood forecast level to which a river will rise and when it is likely to reach its peak or crest, is shown through hydrographs. Other information includes, 1) the likelihood of a river exceeding minor, moderate, or major flooding, 2) the likelihood of a river exceeding certain level, volume, and flow of water at specific points on the river during 90 day periods, and 3) a map of areas surrounding the forecast point that provides information about major roads, railways, landmarks, etc. likely to be flooded, the levels of past floods, etc.