An extended data set of river discharges for validation of general circulation models

Using existing measurements of streamflow data, we present a new data set of river discharges to the ocean, for use in validating climate models. This data set includes annual mean discharges for 981 rivers, representing approximately 824,500 m(3)/s of global river discharge. This is about 65% of contemporary estimates of continental precipitation minus continental evaporation (P-E). Using our new data set, we present a self-consistent water budget over continents. We find that rivers with annual mean discharges between about 250 m(3)/s and about 20,000 m(3)/s closely follow a power law size distribution. We estimate the total flow from rivers smaller than 250 m(3)/s by assuming they obey the same power law size distribution. Under this assumption, the estimated total flow from these rivers is about 33% of P-E. Including an existing estimate of soil moisture entering the ocean underground, our estimated total flow into the ocean is within about 2% of contemporary estimates of continental P-E. Our data set is available in digital format.