What is the standard for water level customization? What is its definition?

Definition of water level: the height of free water surface and underground water surface from datum level in rivers, lakes, reservoirs and oceans. Water level refers to the elevation of the free water surface relative to a certain base surface, and the distance between the water surface and the river bottom is called water depth. The datum plane used to calculate the water level can be the datum plane with a certain characteristic sea level elevation as zero point, which is called absolute datum plane, and the datum plane of the Yellow Sea is commonly used.

You can also use the elevation of a specific point as a reference to calculate the zero point of the water level, which is called the base surface of the station. Water level is the most intuitive factor to reflect water regime, and its change is mainly caused by the increase or decrease of water quantity. Water level hydrograph is a curve of water level changing with time at a certain place with time as abscissa and water level as ordinate.

Extended data:

There are usually two kinds of datum planes representing water level: one is absolute datum plane, and the other is datum plane of station. By the end of 20 14, the absolute benchmark adopted by China is the benchmark of the Yellow Sea, which is based on the characteristic sea surface of a seaside location in the Yellow Sea and Haikou. Wusong base has been used in our province before. In order to compare the water levels of various stations, the conversion relationship between the Yellow Sea and Wusong datum is indicated in the Hydrological Yearbook.

For example, in Changsha water level station, the datum used is Wusong datum, which is converted into the initial water level of the Yellow Sea datum, then: the water level above the Yellow Sea datum = the current observed water level (Wusong datum)-the 2.280m datum of this station is a fixed datum dedicated to the hydrological station, and the water level elevation is calculated as zero point slightly lower than the lowest water level or the lowest river bed in the past years.

Baidu encyclopedia-water level

Baidu Encyclopedia-Water Level (Cartographic Terminology)