"A dataset of historical monthly streamflow at the farthest downstream stations for the world’s 925 largest ocean-reaching rivers has been created for community use. Compared with previous studies, the new dataset has improved homogeneity and enables more reliable assessments of decadal and long-term changes in continental freshwater discharge into the oceans." The data are in the form of time series.
National Center for Atmospheric Research Staff (Eds). Last modified 09 Oct 2013. "The Climate Data Guide: Freshwater Discharge: 1948-2004." Retrieved from https://climatedataguide.ucar.edu/climate-data/freshwater-discharge-1948-2004.