AN IMPROVED RESOLUTION SPATIALLY DISTRIBUTED GLOBAL SEDIMENT FLUX MODEL

Abstract

The magnitude of a river’s sediment discharge provides insight to many ongoing processes in the upstream basin, in particular the basin-averaged erosion rate and the pace of landscape evolution. Knowledge of sediment discharge is applied in agriculture, water quality, calculating dam life expectancy, delta and alluvial fan dynamics, long-term nutrient cycling, and coastal morphology and dynamics. Few models of earth surface sediment processes have been created for the global scale. This thesis improves by a factor of 100 the resolution of a global, spatially-distributed sediment flux model developed by Pelletier (2012) that explicitly differentiates the detachment of sediment from hillslopes and the movement of sediment down-gradient via riverine transport. Using data for monthly precipitation, vegetation cover, slope, soil grain-size distribution, and two free parameters, the model replicates the sediment yield of 128 global rivers with a Pearson correlation coefficient of 0.73. The parameters that minimize the sum of squared residuals are c1 = 0.060 and c2=3 m s-1. Residual analysis indicates that low-magnitude sediment yields are over predicted and high magnitude sediment yields are under predicted, though this trend may be a function of errors in the routing algorithm used. Residuals are statistically independent of upstream basin area.