Navigation and service

Freshwater Fluxes into the World Oceans (GRDC, 2004) - online only

Recommended citation: Couet, Thomas de and Thomas Maurer (2004):Surface Freshwater Fluxes into the World Oceans / Thomas de Couet; Thomas Maurer. Global Runoff Data Centre. Koblenz: Federal Institute of Hydrology (BfG), 2004.

Freshwater input from continents into the oceans is of major interest in research concerned with global monitoring of freshwater resources, the flux of matter into coastal areas and the sea, or the influence of freshwater fluxes on circulation patterns. GRDC calculated the mean annual Surface Freshwater Fluxes into the World Oceans on the basis of a 0.5° source grid optimised for flow path detection. By application of GIS analysis procedures, the specific catchments of 12.000 individual grid cells that form the fringe of the continents were determined so much as all adjacent continental grid cells were co-registered with their respective fringe grid cell through which they drain to the oceans.

World Map with Surface Freshwater Fluxes Surface Freshwater Fluxes to the World Oceans of 5° continental coastline cells (GRDC, 2004)Surface Freshwater Fluxes to the World Oceans of 5° continental coastline cells, GRDC 2004 (click to enlarge)

For 251 watersheds whose outlet is represented by a GRDC station close to the mouth and representing an upstream catchment greater than 25,000 km², the long term annual runoff is derived from observed river discharges. Relating the annual volume at this station to their upstream catchment area and the mean monthly precipitation 1961-1990, a runoff coefficient (RC) for the watershed was calculated. From land areas not integrally captured by a GRDC station, mean annual runoff was estimated by runoff coefficients (RC) by means of regionalisation from nearby monitored areas taking into account data from another 1378 GRDC stations close to the coastline.

This calculation of Surface Freshwater Fluxes into the World Oceans replaces previous publications based on the data of 161 discharge stations (GRDC, 1996) and 181 stations (GRDC, 1998).

This Page

© 2017 BfG