Global suspended sediment and water discharge dynamics between 1960 and 2010: Continental trends and intra-basin sensitivity

Establishing a quantitative description of global riverine fluxes is one of themain goals of contemporary hydrol-ogy and geomorphology. Herewe study changes in global riverinewater discharge and suspended sediment fluxover a 50-year period, 1960-2010, applying a new version of theWBMsed (WBMsed v.2.0) global hydrologicalwater balancemodel. A newfloodplain component is introduced to better representwater and sediment dynam-ics during periods of overbank discharge. Validated against data from 16 globally distributed stations, WBMsedv.2.0 simulation results show considerable improvement over the original model. Normalized departure froman annual mean is used to quantify spatial and temporal dynamics in both water discharge and sediment flux.Considerable intra-basin variability in both water and sediment discharge is observed for the first time in differ-ent regions of the world. Continental-scale analysis shows considerable variability in water and sediment dis-charge fluctuations both in time and between continents. A correlation analysis between predicted continentalsuspended sediment and water discharge shows strong correspondence in Australia and Africa (R2 of 0.93 and 0.87 respectively), moderate correlation in North and South America (R2 of 0.64 and 0.73 respectively) and weak correlation in Asia and Europe (R2 of 0.35 and 0.24 respectively). We propose that yearly changes inintra-basin precipitation dynamics explain most of these differences in continental water discharge andsuspended sediment correlation. The mechanism proposed and demonstrated here (for the Ganges, Danubeand Amazon Rivers) is that regions with high relief and soft lithology will amplify the effect of higher than aver-age precipitation by producing an increase in sediment yield that greatly exceeds increase in water discharge.