THE ROLE OF PORE PRESSURE GENERATION IN SEDIMENT TRANSPORT WITHIN ALLUVIAL BASINS

Here we study of the coupling between compaction, sediment transport, and overpressure generation processes within alluvial basin. A one-dimensional diffusion based sediment transportation equation was coupled to a cross sectional model of groundwater flow to investigate the dynamic feedbacks between the two systems in an evolving, idealized continental synrift dispositional environment. Results suggest that overpressure generation and compaction has first order effect on sediment transport. Varying basin permeability from 10^-16 m² to 10^-19 m² resulted in a transition from near hydrostatic to near lithostatic pressure and resulted in compaction disequilibrium which reduced overall basin length by 20%. It also caused the gravel front retreat by more than 10% and decreased overall basin thickness decreased by 10%. When a 3 orders of magnitude permeability contrast between sand (10^-16 m²) for proximal basin and shale (10^-19 m²) for distal basin was imposed, a hinge line developed in the chronostratigraphic layers. On the other hand sediment transport only have a second order effect on overpressure generation. Our results are consistent with field observations reported by Rusciadelli & Simone (2007) for the Italian Apennines.