Global Composite Runoff Data Set 1.0

The Global Runoff Data Centre (GRDC) and the Institute for the Study of Earth Ocean and Space at the University of New Hampshire (UNH) have teamed up to develop methods and data products allowing for the re-distribution of observed global river discharge data from GRDC data archives along grid-based, simulated river networks. These simulated river networks are at 30-minute (~50 km at the equator) spatial resolution and were developed at UNH.

The present data set demonstrates the potential of combining observed river discharge information with a climate-driven Water Balance Model in order to develop composite runoff fields which are consistent with observed discharges. Such combined runoff fields preserve the accuracy of the discharge measurements as well as the spatial and temporal distribution of simulated runoff, thereby providing the best estimate of terrestrial runoff over large domains.

The method applied in the preparation of this data set utilizes a gridded river network at 30-minute spatial resolution to represent the river flow pathways and to link the continental land mass to oceans through river channels. Selected gauging stations from the Global Runoff Data Centre data archive were co-registered to the UNH Simulated Topological Network (STN-30). Inter-station regions between gauging stations along the STN-30 network were identified. Inter-station discharge and runoff were calculated to compare observed runoff with outputs from the water balance model (WBM) simulation. Correction coefficients based on the ratio of observed and simulated runoff for inter-station areas were calculated and applied against simulated runoff to create composite runoff fields.

Global Composite Runoff Data can be accessed online through Station Data Explorer, Basin Data Explorer, and Runoff Data Explorer. Data at global and continent scales can be downloaded directly from the website at [http://www.grdc.sr.unh.edu/html/Data/index.html].

A CD-ROM has also been prepared. It contains not only UNH-GRDC Composite Runoff Fields v1.0 but also intermediate data sets, such as station attributes and long-term monthly regimes of the selected gauging stations. Also included on the CD are the STN-30, STN-30 derived attributes for the selected stations, and gridded fields of the inter-station regions along STN-30. An HTML-based data explorer was developed to help users of the CD-ROM view the data. With a standard web browser and the CD-ROM, it is possible to navigate from a global view of the data, down to a subbasin or station level.

A report describing the Global Composite Runoff Data Set can be downloaded in PDF format from the Global Composite Runoff Data Set 1.0 Website (http://www.grdc.sr.unh.edu/) or ordered free of charge from GRDC ([e-mail]) or WMO ([e-mail]).