Hydrology

Water level at the point of greatest depth at the average elevation for a natural body of water, and at the normal operating elevation for an artificial body of water.

Average rainfall over a year: it is obtained mostly by adding the average daily rainfalls of the year and dividing the result by the number of days in the year.

The nature of the tidal range is different if the water level is influenced by a human control of the tidal range (dam or other structure affecting the water level) or if it is only influenced by natural factors (rainfall,

Mean variation in the water level of a body of water (in metres given to the nearest decimetre), excluding flooding and drainage periods, for a year of normal operation. The calculation of an interannual tidal range is as…

Frequency at which the water line of the body of water is changing altitude.

Average flow over a year: it is most often obtained by adding the average daily flows of the year and by dividing the result by the number of days in the year.

Elevation of the water line of a man-made body of water under normal conditions of use of the structure that generates and regulates this water body (usually a dam). The normal operating water level is defined by…

Usual average altitude of the water line of a natural body of water. The average elevation is calculated by regularly measuring the height of the water line of the water body using a scale, indexed on the geographic levelling in force or any other technical means (probe, sounding line or other) and on a given period (calendar year or other period). For lack of regular measurements, especially for smaller water…

Vertical elevation of a place or object relative to a basic level. Altitude is also a value that expresses a difference between a given point and an average level. On land, this level is usually the sea level (or "zero level"). Specifically, the altitude of the body of water is considered as average for natural water bodies and as normal operating level or normal water retention level (NR) for man-made water bodies. The…