On the basis of these considerations, the above-mentioned sensitivity parameters were chosen in this study. As a result, a total of nine parameters were investigated by applying physical feasible ranges for each parameter. The calculated deposited amount of each sensitivity simulation was compared to the simulation results of a reference case computation and to the amount of deposits calculated from measurements (given in Table 3). The reference case computations were done on the coarser gird to save computational time. The definitions of the input parameters for the reference case are given in Table 2.

Table 2

Numerical parameters | |

Grid resolution | Coarser grid (100 × 40 × 10) |

Time step | Varying time step with an average time step of 10,000 seconds |

Discretization scheme | Second-order scheme |

Active layer thickness | 10 cm |

Physical parameters | |

Initial grain size distribution | See Table 1 |

Roughness | 2 cm |

Bed load transport formula | van Rijn (1984b) |

Parameters correlated to cohesive sediments | |

Fall velocity | Zanke (1977), see Table 1 |

Critical shear stress for bed particles | Shields (1936) |

Numerical parameters | |

Grid resolution | Coarser grid (100 × 40 × 10) |

Time step | Varying time step with an average time step of 10,000 seconds |

Discretization scheme | Second-order scheme |

Active layer thickness | 10 cm |

Physical parameters | |

Initial grain size distribution | See Table 1 |

Roughness | 2 cm |

Bed load transport formula | van Rijn (1984b) |

Parameters correlated to cohesive sediments | |

Fall velocity | Zanke (1977), see Table 1 |

Critical shear stress for bed particles | Shields (1936) |

Table 3

Method . | Deposits [m³] . | Deviation, reference [%] . | Deviation, measured [%] . |
---|---|---|---|

Measured | 51,000 | −10 | 0.0 |

Computed, reference case | 56,850 | 0.0 | 11 |

Computed, 300 seconds fixed time step (30,000 time steps) | 54,721 | −3.7 | 7.3 |

Computed, fine grid and 300 seconds fixed time step | 50,031 | −14 | −1.9 |

Computed, with initial bed grain size distribution from reference case | 56,239 | −1.1 | 10 |

Computed, fall velocities from Winterwerp formula for 3 finest fractions | 45,305 | −20 | −13 |

Computed, 5 × larger fall velocities for 3 finest fractions | 83,961 | 48 | 65 |

Computed, roughness from 2 to 5 cm | 47,769 | –16 | −6.7 |

Computed, roughness from 2 cm to a value calculated using the van Rijn formula in equation (1) | 51,947 | –8.6 | 1.8 |

Computed, active layer thickness from 0.1 to 0.2 m | 57,635 | 1.4 | 13 |

Computed, active layer thickness from 0.1 to 0.02 m | 57,144 | 0.5 | 12 |

Computed, Engelund–Hansen formula | 46,140 | −19 | −11 |

Computed, van Rijn suspended load formula only | 60,458 | 6.3 | 19 |

Computed, first-order scheme instead of second-order scheme | 59,616 | 4.9 | 17 |

Computed, cohesion equivalent to 1 Pa on 4 finest fractions | 70,395 | 24 | 38 |

Computed, cohesion equivalent to 0.1 Pa on 4 finest fractions | 67,022 | 18 | 31 |

Computed, cohesion equivalent to 0.01 Pa on 4 finest fractions | 58,264 | 2.5 | 14 |

Method . | Deposits [m³] . | Deviation, reference [%] . | Deviation, measured [%] . |
---|---|---|---|

Measured | 51,000 | −10 | 0.0 |

Computed, reference case | 56,850 | 0.0 | 11 |

Computed, 300 seconds fixed time step (30,000 time steps) | 54,721 | −3.7 | 7.3 |

Computed, fine grid and 300 seconds fixed time step | 50,031 | −14 | −1.9 |

Computed, with initial bed grain size distribution from reference case | 56,239 | −1.1 | 10 |

Computed, fall velocities from Winterwerp formula for 3 finest fractions | 45,305 | −20 | −13 |

Computed, 5 × larger fall velocities for 3 finest fractions | 83,961 | 48 | 65 |

Computed, roughness from 2 to 5 cm | 47,769 | –16 | −6.7 |

Computed, roughness from 2 cm to a value calculated using the van Rijn formula in equation (1) | 51,947 | –8.6 | 1.8 |

Computed, active layer thickness from 0.1 to 0.2 m | 57,635 | 1.4 | 13 |

Computed, active layer thickness from 0.1 to 0.02 m | 57,144 | 0.5 | 12 |

Computed, Engelund–Hansen formula | 46,140 | −19 | −11 |

Computed, van Rijn suspended load formula only | 60,458 | 6.3 | 19 |

Computed, first-order scheme instead of second-order scheme | 59,616 | 4.9 | 17 |

Computed, cohesion equivalent to 1 Pa on 4 finest fractions | 70,395 | 24 | 38 |

Computed, cohesion equivalent to 0.1 Pa on 4 finest fractions | 67,022 | 18 | 31 |

Computed, cohesion equivalent to 0.01 Pa on 4 finest fractions | 58,264 | 2.5 | 14 |

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