The grain size distribution was analysed by taking core samples. It was shown that the grain sizes in the reservoir range from clay to gravel. The numerical model computed the sediment transport by nine different fractions. The initial grain size distribution on the bed is given in Table 1. The distribution is based on measurements of the main river bed and was initially given uniformly over the whole geometry. The distribution of the inflowing sediment fractions is also based on measurements (Astor et al. 2014) and is also given in Table 1. This was used as the upstream boundary conditions for the numerical model.
Sediment characteristics for the different sizes
| Size number . | Diameter [mm] . | Initial fraction at bed, reference case [%] . | Fall velocity Winterwerp & van Kesteren (2004) [mm/s] . | Fall velocity, Zanke (1977), reference case [mm/s] . | Inflow sediments [%] . |
|---|---|---|---|---|---|
| 1 | 20 | 88 | – | 568 | 0 |
| 2 | 3 | 8.4 | – | 216 | 0 |
| 3 | 1.3 | 2.3 | – | 136 | 0 |
| 4 | 0.4 | 1.3 | – | 56 | 2 |
| 5 | 0.13 | 0 | – | 11 | 11 |
| 6 | 0.04 | 0 | – | 1.1 | 19 |
| 7 | 0.02 | 0 | 0.027 | 0.27 | 35 |
| 8 | 0.005 | 0 | 0.0069 | 0.017 | 12 |
| 9 | 0.002 | 0 | 0.0028 | 0.0027 | 21 |
| Size number . | Diameter [mm] . | Initial fraction at bed, reference case [%] . | Fall velocity Winterwerp & van Kesteren (2004) [mm/s] . | Fall velocity, Zanke (1977), reference case [mm/s] . | Inflow sediments [%] . |
|---|---|---|---|---|---|
| 1 | 20 | 88 | – | 568 | 0 |
| 2 | 3 | 8.4 | – | 216 | 0 |
| 3 | 1.3 | 2.3 | – | 136 | 0 |
| 4 | 0.4 | 1.3 | – | 56 | 2 |
| 5 | 0.13 | 0 | – | 11 | 11 |
| 6 | 0.04 | 0 | – | 1.1 | 19 |
| 7 | 0.02 | 0 | 0.027 | 0.27 | 35 |
| 8 | 0.005 | 0 | 0.0069 | 0.017 | 12 |
| 9 | 0.002 | 0 | 0.0028 | 0.0027 | 21 |