waterpeil

Waterpeil is the vertical height of the surface of a body of water, such as a river, lake, estuary, or reservoir, relative to a reference datum. It fluctuates with tides, rainfall, evaporation, river discharge, wind, and atmospheric pressure. Waterpeil is a fundamental parameter in hydrology, navigation, flood management, and water resource planning.

Water levels are measured with gauges that produce time series of height above a reference level. In many countries the datum is a local vertical reference; in the Netherlands the common reference is Normaal Amsterdams Peil (NAP). Other regions use mean sea level or a national datum. Observations include tide-induced highs and lows, river stages, and target levels for reservoirs. Data can be transformed between datums using offset values and local corrections.

Applications of waterpeil include flood risk management, where dikes, sluices, pumping stations, and reservoirs are operated to keep levels within safe limits. For maritime operations, accurate water levels are essential for navigation, docking, and harbor planning. Waterpeil also supports climate and hydrological research, including forecasting, drought assessment, and infrastructure design.

Data on waterpeil are provided by national hydrological services, weather agencies, and satellite observations. Public time series and real-time measurements enable trend analysis, flood forecasting, and informed decision-making for water management and urban planning.