The figure(s) below are from 2013 draft US National Climate Assessment.
Rivers Discharge 48-04 - Dai+ 1108.pdf
from Dai's "Rivers Discharge, 1948-2004 - Dai 1108".
Vobs is the river volume, in cubic kilometers per year, at the station indicated.
bobs is the trend per year over the 1945-2005 period. Bold is statistically significant. Negative is decreasing flow trend.
Climate Change Impact on Stream Flow Varies by Location 0213.rtf
Dai's 1108 graphs above show that flows in the Ganges/Brahmaputra and Mekong Rivers approach zero (8% of peak) during the dry season. The Indus, Yellow, Salween, and Irawaddy Rivers face similar problems. All depend heavily on monsoon rains, but during the dry season on meltwater from the Himalayas. The same can be said, but more weakly, of the Changjiang (Yangtze River). This makes them vulnerable to running out of water during years when flow is low, or when Himalayn glaciers vanish.
Flows also are very low (4-8% of peak) in the Yenisey and Lena rivers, during the frozen season. Flows change more for the Orinoco River between the rainy and dry seasons than they do for the Amazon. Flows in the Congo and Parana Rivers are not very sensitive to season, and Amazon flows only somewhat more sensitive.
Typical monthly river basin precipitation and flows for the world's 10 largest rivers, by volume.
Left axis is for flows, right axis for precipitation.
Year-to-year variability ranges from 6:1 for the Uruguay River and 3:1 for the Mississippi, Niger and Xi Rivers, to 1.4:1 for the Amazon River. Years with low water flows in some rivers leave them at risk of running dry.
Dai's graphs below show annual discharge into the world's ocean basins. Discharge into the Arctic Ocean rose, while into the Pacific and Indian Oceans it fell.
Section Map: Water