Severe thunderstorms are expected from central Texas to middle Tennessee and Kentucky this afternoon into tonight. Large hail and damaging winds are the main threats. Heavy to excessive rainfall may produce areas of flooding today and tonight from central Texas into the lower Mississippi Valley.
COMMON HYDROLOGIC TERMS AND DEFINITIONS
| BANKFULL: An established river stage/elevation at a given location along a river which is intended to represent the maximum safe water level that will not overflow the river banks or cause any significant damage within the river reach.
BASIN: Whole geographic area having a common outlet (such as a river, stream, or lake) for its surface runoff. Also known as drainage area or watershed. CREST: The highest stage or level of water at a specific point before the water begins to recede. FLOOD FREQUENCY: The chances that a particular flood event will occur during any given year. The greater the flood, the higher the "Year Flood" Value, but the less chance of occurrence. (i.e. a "100 Year Flood" has a 1% chance of occuring each year). FLOOD STAGE: The elevation at which overflow of the natural banks of a waterway begins to cause damage or presents a flood-damage hazard near the gage where the elevation is measured (can also be expressed in terms of flood flow). FLOW: The volume of water that passes through a point of a river during a given time. Usually expressed in cubic feet per second (cfs). HYDROGRAPH: A graph showing stage, discharge, or other property of a river with respect to time. REACH: The length of area between two specific points (usually between 2 gages) along a river, stream, or channel. RUNOFF: The part of precipitation that flows toward a river or stream on the surface of the ground, or through the soil before returning to the surface. STAGE: The level of the surface of a river or lake above a predetermined base elevation (or "datum"). WATER YEAR: October 1 through September 30. |
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