This tool calculates the yearly siltation inside the harbour basin based on the theory of Van Rijn (Harbour siltation and control measures, 2012). The tool uses tidal characteristics (mean high water MHW, mean low water MLW and ebb/flood flow velocities) and harbour characteristics (Total surface area, entrance width and entrance configuration) to calculate the exchanged volumes of water and suspended sediment, variable concentrations and the yearly sedimentation within the harbour basin.
Default values for input parameters are presented in the long descriptions (place your mouse on input parameter name).
Measurements from reference projects reported in Van Rijn (2012) show the following typical range of yearly siltation (m sediment thickness):
Salt/brakish conditions | Lower range | Upper range |
Harbour basin | 1.0 m | 2.0 m |
Harbour entrance | 2.0 m | 5.0 m |
Fresh conditions | Lower range | Upper range |
Harbour basin | 0.3 m | 0.4 m |
Harbour entrance | 1.0 m | 3.0 m |
A number of user input fields are provided which can be used to adjust the calculation according to the local situation. Default values are provided for each input field. The following inputs are defined:
| Default Value | Unit | Min. | Max. | Brief Description |
Width harbour entrance | 200 | m | 0 | 1000 | Width of the harbour entrance (distance between breakwaters). |
Initial bottom level inside harbour | -15 | m+MSL | -50 | -0.5 | Level of bottom of harbour (constant). |
Entrance factor: horizontal eddy flood flow | 0.03 | - | 0 | 0.25 | Entrance factor inducing horizontal eddy during flood flow. |
Entrance factor: horizontal eddy ebb flow | 0.03 | - | 0 | 0.25 | Entrance factor inducing horizontal eddy during ebb flow. |
| Default Value | Unit | Min. | Max. | Brief Description |
Phase difference tidal level-flow | -90 | ° | -360 | 360 | Phase difference in tidal level versus tidal flow. In case of 0° flow velocity is peaking together with the maximum water level. |
Water density outside harbour | 1020 | kg/m3 | 500 | 2000 | Density of water outside harbour. |
Maximum density difference outside-inside | 0 | kg/m3 | 0 | 100 | Maximum density difference between outside and inside the harbour. Water density inside harbour will be lowered with this value. |
| Default Value | Unit | Min. | Max. | Brief Description |
Concentration outside harbour (constant) | 0.1 | kg/m3 | 0 | 10 | Constant mud concentration outside harbour |
Concentration outside harbour (max variable) | 0.02 | kg/m3 | 0 | 10 | Maximum variable mud concentration outside harbour |
Settling velocity sediment | 0.0003 | m/s | 0 | 1 | Settling velocity of suspended sediment (silt/clay) |
Bulk density | 400 | kg/m3 | 0 | 3000 | Bulk density after sedimentation of sediment (silt/clay) |
| Default Value | Unit | Min. | Max. | Brief Description |
Sensitivity parameter: Flow velocity | 0 | % | 0 | 50 | Possible change or uncertainty in Flow velocity |
Sensitivity parameter: Entrance Width | 0 | % | 0 | 50 | Possible change or uncertainty in Entrance width harbour |
Sensitivity parameter: Susp. Sediment Concentration | 0 | % | 0 | 50 | Possible change or uncertainty in Suspended Sediment Concentration |
Sensitivity parameter: Settling velocity | 0 | % | 0 | 50 | Possible change or uncertainty in Settling velocity sediment |
The main limitation of this tool is that both hydrodynamics and harbour are strongy simplified. Simplifying the harbour to one unit results into an average concentration and average sedimentation over the complete area of the harbour. Both concentration and sedimentation will differ significantly over the total harbour.
The following files (.dsproj) can be downloaded and loaded into CoDeS to serve as examples. They are not based on actual projects, but are intended as illustration.
Unzip the files to an convient folder (but make sure the file structure does not change), and open the .dsproj file from within CoDeS.