| Changes in paleo coastline position through time are a function of both local sea-level and sediment flux. While past sea-level changes are fairly well understood, reconstructing the amount of sediment transported by rivers is very difficult. This justifies our proposal which is to untangle sediment flux histories from the sedimentary record by combining field data with new forward and inverse numerical modeling techniques. Numerical models are useful tools to mimic sedimentary processes that occur in rivers, deltas end shorefaces. Because the world is three-dimensional, many models describe the sedimentary processes in 3D, but these models are very elaborate and require long calculation times. A new methodology to collapse 3D information in 2D will be used to develop a new model (2DStratSim). This model simulates an average down-slope profile including uncertainties due to cross-slope deposition and it will be coupled to a module to calculate sediment flux and water discharge based on basin area and relief, temperature, river runoff, lithology and glacier cover. Simulations will be very time-efficient. This enables us to use 2DStratSim in an inverse modeling scheme which is not possible for 3D models. The inversion scheme will infer sediment-flux histories from real-world data. 2DStratSim will be tested and applied using published field data which include Holocene and Pre-Holocene river- and marine systems. Since the behavior of coastal systems under fallings sea-level conditions is still not well understood, we will study a prograding beach ridge and delta in two high-sediment supply areas: Aceh, Sumatra and Hudson Bay, Canada and use this data to validate 2DStratSim and test the inversion scheme. This proposal combines new innovative approaches to form a novel methodology which will teach us much more about the role of varying sediment flux in modern and ancient sedimentary systems |
