waterstands

Waterstand is the height of the surface of a body of water at a given location and time, typically measured relative to a reference vertical datum such as mean sea level. Waterstands can refer to a single measurement or to a time series observed at multiple sites. They are important indicators in hydrology, flood risk assessment, navigation, and water resources management.

Measurement methods range from traditional gauging stations with stilling wells and floats to modern sensors that use pressure, radar, or acoustic technologies. Ground-based systems continuously record water levels, while satellite-based techniques such as radar altimetry provide broader coverage and help fill gaps in ground observations. Measurements are often collected at regular intervals and archived for analysis and forecasting.

A datum or reference level is required to interpret waterstands. Common choices include mean sea level or a local vertical datum. Reported heights are usually given in meters (or centimeters) above the chosen datum. Conversions between datums may be necessary when comparing data from different regions.

Applications of waterstands include flood forecasting and warning, design and operation of dams and reservoirs, river navigation, coastal engineering, and climate research. Data are produced by national hydrological services, meteorological agencies, and international monitoring programs, and are made available to the public and to decision-makers. Quality control, calibration, and metadata are important for ensuring the accuracy and comparability of waterstand records over time.