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Introduction & summary

In this tool (breakwater design) you can compute required dimensions, overtopping, cross-sections and costs of rubble mound breakwaters.
The tool requires at least a breakwater and bathymetry data (you can inspect the generic data availability in the top panel of the tool).
Optionally, any generic wave data can also be used, in order to fill the wave condition fields.

Computations of breakwater dimensions and costs are based on rough guidelines in the Rock manual.
Results of the breakwater tool should therefore be interpreted with a considerable range of uncertainty.

How to use the tool

  1. Open a new project
  2. Start in Generic Data by defining:
    1. a Coastline,
    2. a Cross-shore profile (both a slope and a spatial varying field are supported by this tool),
    3. at least one breakwater structure. Make sure that the breakwaters intersect with the coastline,
    4. extreme wave conditions (optional).
  3.  Open the Breakwater design tool.
  4. Provide input according to the user input field description below. After selecting the breakwater, grey dots are shown along the breakwater to indicate the cross sections that will be calculated.
  5. Press the play button to start the breakwater design calculation.
  6. After the calculation, subwindows are presented below the map which hold the following information:
    1. Cross-sectional breakwater design
      For each cross-section along the breakwater (indicated by the grey dot), this plot shows the cross-sectional dimensions of the armour, filter and core layer.  Also the water level during storm conditions is indicated. The slider below the plots allows for selecting a different cross-section. The cross-sections are numbered in offshore direction.
    2. Longitudinal breakwater design
      This plot shows the breakwater dimensions along the breakwater's longitudinal axis. The water level, the depth profile and the crest height are all indicated in this plot. At every cross-section a vertical line is shown, corresponding to the breakwater height at that specific cross-section. 
    3. Output properties
      This panel shows a summery of the input and output parameters per cross-section. The slider below the plots allows for selecting a different cross-section.

  7. Press the delete button to delete the output from the map.

User input fields

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:

Generic computation settings

 Default ValueUnitMin.Max.Brief Description
Structure    Select one of the breakwater structures.
Safety level    Select the design safety level which determines the amount of allowable wave overtopping.
Allowable overtopping0.03l/s/m0.0350Based on the selected safety level, this shows the allowable overtopping for the breakwater design.
Depth type    Toggle between Varying and Uniform. In case of a Varying depth type, the bottom depth provided by Generic Data is used.
Uniform depth10m0.019999In case a uniform depth type is selected, provide the water depth value.
Automated crestheight calculationTrue TrueFalseIn case this is selected, the crest height will be automatically calculated based on the design criteria. In case this option is not selected, provide a crest height.
Slope3-0.25100Provide the outer slope of the breakwater (as 1: .., e.g. 1:3). The inner and outer slopes are considered equal.
Crest width5m0.01999Provide the width of the top of the breakwater (crest).
Crest height0m, MSL0.01999In case the automated crest height calculation is switched off, provide the crest height of the breakwater.


Design storm conditions

Provide the design storm condition. By clicking on the () button, you can also select extreme wave conditions from the generic data.

 Default ValueUnitMin.Max.Brief Description
LocationOffshore OffshoreNearshoreIndicate whether the design storm conditions are provided at an offshore or nearshore (at the breakwater toe). Using lineair wave theory the wave height is transformed to nearshore conditions in case offshore storm conditions are provided.
Hs3m0.0120Significant wave height during design storm conditions.
Tp12s0.0120Wave peak period during design storm conditions.
Water level1m, MSL-1010Provide the water level at the tip of the breakwater w.r.t. to MSL that is present during storm conditions.
Storm duration6hr0.148Total duration of the storm. This is used to calculate the total number of waves that is expected to reach the breakwater.
Breaker parameter0.73-0.00011Defines the wave height at which waves start to break. The maximum wave height is defined by the breaker parameter times the local waterdepth.
Offshore depth100m09999In case the design storm conditions are provided at an offshore location, provide the offshore depth of that location. Using lineair wave theory, the wave height is transformed to nearshore conditions.


Armouring

 Default ValueUnitMin.Max.Brief Description
Armour typeRock-  Currently only a rock armouring layer is supported.
Armour density2650kg/m310005000Density of the armour layer.
Water density1025kg/m310001250Density of the water, which should be in between 1000 kg/m(e.g. fresh water) and 1025 kg/m3 (e.g. salty water).
Layer coefficient1kt01 
Notional permeability0.4P0.010.9 
Damage number2S117 


Reduction factors

 Default ValueUnitMin.Max.Brief Description
Berm reduction1-01Reduce forces in case of expected wave breaking on a berm. A value of 0 indicates the absence of wave breaking due to a berm, a value of 1 indicates full reduction of wave breaking due to a berm.
Roughness reduction0.4-0.11Indicate whether the roughness of the armour material reduces wave run-up. 0.1 indicates the absense of wave-run up reduction (smooth surface) whilst 1 indicates full reduction (rough surface).
Angle of incidence0deg cross-shore-9090Indicate whether the waves are approaching the breakwater under an angle.


Unit cost price

 Default ValueUnitMin.Max.Brief Description
Unit rate armour20€/m30inf.Provide the unit rate for the armour layer material which is used to calculate the cross-sectional breakwater costs.
Unit rate filter15€/m30inf.Provide the unit rate for the filter layer material which is used to calculate the cross-sectional breakwater costs.
Unit rate core10€/m30inf.Provide the unit rate for the core layer material which is used to calculate the cross-sectional breakwater costs.


Tool limitations

The following processes are not included in the tool: waves approaching under a cross shore varying angle, bed level changes caused by wave reflection, shoals causing wave breaking etc. Besides, the tool only provides linear cross-sections comprising of 3 default materials, without providing information on the breakwater toe or round heads. Results of the breakwater tool should therefore be interpreted with a considerable range of uncertainty.

Example cases

The following files (.dsproject) 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 .dsproject file from within CoDeS.

Breakwater design.zip

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