TY  - JOUR
A1  - Cordonnier, Guillaume
A1  - Bovy, Benoit
A1  - Braun, Jean
T1  - A versatile, linear complexity algorithm for flow routing in topographies with depressions
JF  - Earth surface dynamics
N2  - We present a new algorithm for solving the common problem of flow trapped in closed depressions within digital elevation models, as encountered in many applications relying on flow routing. Unlike other approaches (e.g., the Priority-Flood depression filling algorithm), this solution is based on the explicit computation of the flow paths both within and across the depressions through the construction of a graph connecting together all adjacent drainage basins. Although this represents many operations, a linear time complexity can be reached for the whole computation, making it very efficient. Compared to the most optimized solutions proposed so far, we show that this algorithm of flow path enforcement yields the best performance when used in landscape evolution models. In addition to its efficiency, our proposed method also has the advantage of letting the user choose among different strategies of flow path enforcement within the depressions (i.e., filling vs. carving). Furthermore, the computed graph of basins is a generic structure that has the potential to be reused for solving other problems as well, such as the simulation of erosion. This sequential algorithm may be helpful for those who need to, e.g., process digital elevation models of moderate size on single computers or run batches of simulations as part of an inference study.
Y1  - 2019
U6  - https://doi.org/10.5194/esurf-7-549-2019
SN  - 2196-6311
SN  - 2196-632X
VL  - 7
IS  - 2
SP  - 549
EP  - 562
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Yuan, Xiaoping
A1  - Braun, Jean
A1  - Guerit, Laure
A1  - Simon, Brendan
A1  - Bovy, Benoît
A1  - Rouby, Delphine
A1  - Robin, Cécile
A1  - Jiao, R.
T1  - Linking continental erosion to marine sediment transport and deposition: A new implicit and O(N) method for inverse analysis
JF  - Earth & planetary science letters
N2  - The marine sedimentary record contains unique information about the history of erosion, uplift and climate of the adjacent continent. Inverting this record has been the purpose of many numerical studies. However, limited attention has been given to linking continental erosion to marine sediment transport and deposition in large-scale surface process evolution models. Here we present a new numerical method for marine sediment transport and deposition that is directly coupled to a landscape evolution algorithm solving for the continental fluvial and hillslope erosion equations using implicit and O(N) algorithms. The new method takes into account the sorting of grain sizes (e.g., silt and sand) in the marine domain using a non-linear multiple grain-size diffusion equation and assumes that the sediment flux exported from the continental domain is proportional to the bathymetric slope. Specific transport coefficients and compaction factors are assumed for the two different grain sizes to simulate the stratigraphic architecture. The resulting set of equations is solved using an efficient (O(N) and implicit) algorithm. It can thus be used to invert stratigraphic geometries using a Bayesian approach that requires a large number of simulations. This new method is used to invert the sedimentary geometry of a natural example, the Ogooue Delta (Gabon), over the last similar to 5 Myr. The objective is to unravel the set of erosional histories of the adjacent continental domain compatible with the observed geometry of the offshore delta. For this, we use a Bayesian inversion scheme in which the misfit function is constructed by comparing four geometrical parameters between the natural and the simulated delta: the volume of sediments stored in the delta, the surface slope, the initial and the final shelf lengths. We find that the best-fit values of the transport coefficients for silt in the marine domain are in the range of 300 - 500 m(2)/yr, in agreement with previous studies on offshore diffusion. We also show that, in order to fit the sedimentary geometry, erosion rate on the continental domain must have increased by a factor of 6 to 8 since 5.3 Ma. (C) 2019 Elsevier B.V. All rights reserved.
KW  - river erosion
KW  - sediment-transport model
KW  - efficient method
KW  - inverse analysis
KW  - the Ogooue Delta
Y1  - 2019
U6  - https://doi.org/10.1016/j.epsl.2019.115728
SN  - 0012-821X
SN  - 1385-013X
VL  - 524
PB  - Elsevier
CY  - Amsterdam
ER  -