Long-term trends of basinwide water balance from 1950 to 1990 in 33 major rivers in the world were examined by using annual precipitation and runoff records, as well as the correlation with El Niño/Southern Oscillation (ENSO). The time series of the annual precipitation and the runoff anomalies show the decreasing tendency of precipitation and runoff in Africa, Asia and Eastern part of Russia, and the increasing tendency in North America. The lag-correlation between the precipitation and the Southern Oscillation Index (SOI) showed the annual precipitation in North America and that in Europe had negative correlation with the SOI at the same year and that of one year before, respectively. The time series of annual precipitation and runoff in North America had a negative correlation with those in Europe. In addition, the time series of annual runoff in Africa had a negative correlation with that in North America and Europe. The analyses in this study were based on annual basis. Further analysis based on seasonal or monthly basis may leads to the clearer results.
