Design rule purpose

This design rule is specific to offshore infrastructure and has a simple purpose: to ensure that options generated by Optioneer avoid land or shallow water. Offshore assets are exposed to higher risk when in shallow waters and should obviously avoid any land outcrop as it will be infeasible to install an on-land section.

This seemingly simple challenge for a human designer is actually surprisingly tricky from the perspective of Optioneer engine since not all sections of land are labelled and there is nothing preventing Optioneer to go there. This is particularly problematic in case of complex coastlines. The most versatile approach is to use the bathymetry dataset and set up a threshold of water depth above which the route is considered infeasible.

How to configure

This design rule only requires very little configuration as Optioneer uses the 'elevation' dataset which has to be supplied for every project.

The example below is to illustrate how the design rule works and uses slightly exaggerated assumptions.

The main issue is that landmass datasets often do not coincide with reality of what is happening at complex coastlines. Landmass data below was obtained from recognised public sources.

Using topography / bathymetry datasets appears like a feasible solution to the situation but unfortunately, most elevation datasets are poor quality close to shore (and likewise with bathymetry).

The best results to identify areas where it is infeasible to lay the cable (such as close to shore or around little land outcrops) is to exclude values above a certain threshold.

The only exception to this is when cable is making landfall and therefore there is no alternative.

Important notes

  • When setting up the offshore landfall location, it is important to take into account that this design rule might make the landfall itself infeasible. The landfall point should be placed sufficiently far offshore (a few hundred meters). Landfalls are usually designed in detail separately.

Input / output summary

Input parameters

Name

Default value

Unit

Threshold above which the area is considered to shallow (and therefore has to be avoided)

0

meters

NB: Elevation above sea level is defined as positive. Depth is negative. This means that to instruct Optioneer to avoid water less than 5m deep, users should enter -5m as the threshold.

Output parameters

There is no output of this design rule - it only ensures that areas that should be avoided are in fact avoided.

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