Predicting the terrestrial flux of sediment to the global ocean: a planetary perspective

A new model for predicting the long-term flux of sediment from river basins to the coastal ocean is applied to a global data set of 340 river basins. The model is based on relief, basin area (or, averaged discharge), and basin-averaged temperature. Basin-averaged temperature is determined from basin location (latitude, longitude) and the lapse rate across the basin relief (hypsometric approximation). The sediment flux model incorporates climate through basin temperature and hydrologic runoff. Solutions are provided for each of the major hemispheric climate regions (polar, temperate and tropic). The model successfully predicts the pre-anthropogenic flux of sediment to within the uncertainties associated with the global observations (within a factor of two for 75% of rivers that range across five orders of magnitude in basin area and discharge). Most of the "problem" rivers are associated with low observational loads (often smaller rivers where anthropogenic impacts are often magnified, and temporal variability is high). Model predictions provide a baseline for researchers: (1) to question the quality of observational data where available and disagreement is greatest, (2) to examine a river basin for unusually large anthropogenic influences (i.e. causes of erosion or causes of hinterland sediment retention), and (3) to uncover secondary factors not addressed by our model (lithology, lakes). The model provides a powerful tool to address the impact of paleo-climate fluctuations (warmer/colder; wetter/drier) on the impact of sediment flux to the coastal ocean. (C) 2003 Elsevier B.V. All rights reserved.