WMO Strategic Priority: WIGOS and WIS, Polar and High Mountain Regions, Capacity Development
Status: Ongoing
Funding: Contributions by participating countries
Programmes: Hydrology and Water Resources Programme
Implementation in: Canada, Denmark, Finland, Iceland, Norway, Russian Federation, Sweden, USA
Regions: Region IV: North America, Central America, Caribbean; Region VI: Europe
Donors: Contributions by participating countries
Project Partners: WMO


The Arctic-HYCOS project aims to improve the monitoring of freshwater fluxes into the Arctic Ocean for better climate predictions in the Northern Hemisphere. The project serves as a vital platform for the regular collection and free exchange of Arctic hydrological data among all participants. Main activities include evaluating, maintaining and potentially upgrading existing observational stations.

Network Analysis allow identifying observational stations suitable to evaluate freshwater flux to the Arctic Ocean and Seas and to study changes in Arctic hydrological regimes relative to climate change.



The meaningful use of data requires knowledge about the conditions under which the observations were made. The Arctic-HYCOS database includes metadata to allow users to filter data based on this supplementary information. The following guide provides information on the metadata included in the Arctic-HYCOS database and their definitions.

Drainage area The land area where precipitation falls off into creeks, streams, rivers, lakes, and reservoirs. This land feature can be identified by tracing a line along the highest elevation between two areas on a map, often a ridge. The drainage area for a river basin is measured in a horizontal plane enclosed by the drainage divide outlining the basin. In some cases river, basins may have non-contributing sub-basins, or commonly called enclosed basins, where the runoff stays within the basin and not contributing to the larger basin surrounding the enclosed basin. In the Arctic-HYCOS database, drainage area is defined by catchment size in square kilometres (km2).
Data Quality  A general assessment of the accuracy (and uncertainty) of the continuous discharge estimate from each station. The suggested technique is to form an accuracy assessment for a station’s dataset based on the stability of the station’s rating curve. Aspects to consider include the slope of the rating curve, how well the curve is defined in relation to the number of measurements, the spread of the measurements over the range of the curve, and the stability of the curve over time (weed growth, ice conditions, erosion, deposition, etc.). The accuracy assessment is split by time of the year – open-water and ice-cover conditions – as accuracy may vary throughout the year for some sites, such as poor winter measurements, but excellent open water data, or vice versa.
Land Use Change A “significant” amount of land use change in a basin is defined as greater than 10% of the surface area of the station’s drainage area having been modified in some fashion. In the case of the Canadian RHBN, stations all have a non-significant degree of basin development and are considered to represent pristine, or as a minimum, stable land-use conditions. In the Arctic-HYCOS database, Significant (1) indicates that less than 10% of the surface area of the basin has been modified from natural conditions while Non-significant (0) indicates that more than 10% of the surface area has been modified.
Regulation Identifies  stations in basins with and without “significant” regulation or diversions in the river system. This designation reflects only the physical structures within the waterways upstream of the site; it does not reflect the land use within the basin. The “natural” designation does not infer pristine conditions, but it does infer that there are no control structures upstream. In the Arctic-HYCOS database, Regulated (1) refers to basins with structures controlling more than 5% of the area of the basin while No significant regulation (0) indicates no significant regulation or diversions within the river system less than 5% of the basin area affected, or “natural” conditions.



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Meteorological Service of Canada
Water Survey of Canada

Point of contact:
Dr. Alain Pietroniro

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Danish Meteorological Institute (DMI)

Point of contact:
Mr. Claus Kern-Hansen

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Finnish Environment Institute

Point of contact:
Johanna Korhonen

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Icelandic Meteorological Office

Point of contact:
Dr. Jorunn Hardardó

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Norwegian Water Resources and 
Energy Directorate (NVE)

Point of contact:
Mr. Morten Johnsrud

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Russian Federation

State Hydrological Institute 
of Roshydromet

Point of contact:
Prof. Valery Vuglinsky

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Swedish Meteorological and 
Hydrological Institute

Point of contact:
Cristina Alionte-Eklund

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United States of America

U.S: Geological Survey (USGS)

Point of contact:
Jeff Conaway