Recognition criteria for hydrological observing stations
Note: Hydrological observations include observations and measurements of precipitation; evaporation; evapotranspiration; soil moisture; water levels of rivers, lakes and reservoirs; ice on rivers, lakes and reservoirs; velocity of stream flow; discharge; water quality and groundwater.
Mandatory criteria:
- The observing station was founded at least 100 years ago, observing regularly (at least monthly) at least one hydrological element since then (element(s) to be listed in the References/Remark column) and is in operation as an observing station at the date of nomination.
- Periods of inactivity of the observing station shall not exceed 10%.
- The minimum historic station metadata for the full duration of station operation shall contain actual or derived geographical coordinates including elevation, basin area, known changes of station name and/or station identifier, identified hydrological element(s) and its unit(s) as well as the measurement methods and observing schedule.
- Any known observing station relocation or change in the measurement technique have not significantly affected the hydrological time-series data.
Notes: Documented data homogenization for the observing station is considered compliant with criterion 4. Major river modifications upstream to the hydrological observing station, which changed the drainage area of the river basin (by bringing in or diverting water courses across water divides) or major changes to water use or land use upstream to the hydrological observing station, which significantly altered the hydrological regime at the point of observation, shall be flagged to the Advisory Board and may rule out recognition as centennial observing station.
- All historic observational data and metadata have been digitally archived or will be rescued. Members shall share their plans for data rescue, if applicable.
- The observing station shall be operated according to WMO observing standards according to the Manual on the WMO Integrated Global Observing System (WMO-No. 1160), the Technical Regulations Volume III Hydrology (WMO-No. 49), the Guide to Hydrological Practices (WMO-No. 168) and the Manual on Stream Gauging (WMO-No. 1044).
Note: Explanatory information shall be provided for those stations that do not meet current WMO observing standards.
- The observed and measured data shall be subject to routine quality control procedures according to current WMO guidelines and practices. The quality control processes as well as their results shall be well documented.
Note: A brief description of the routine quality procedures at the observing station shall be provided.
- Members shall do their utmost to maintain nominated stations according to the above recognition criteria.
- Historic observation data and metadata have been or will be made available for scientific research, according to Resolution 1 (Cg-Ext(2021)) – WMO Unified Policy for the International Exchange of Earth System Data. Members shall share their plans for data availability, if applicable.