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Numerical modelling: it all starts with 'why?'

Using the right tools at the right time

Numerical models are sophisticated decision-support tools, but can be time consuming and not needed in every situation. How do we ensure we use the right tools at the right time?

Numerical models of marine physical processes are sophisticated decision-support tools that help gain an understanding on a range of topics, from effects of short-term construction activities to geomorphological and ecological consequences of development and climate change over decades.

However, depending on their level of detail, they can be a time-consuming option which is not needed in every situation.

Often developing a robust conceptual understanding (baseline) and desk analysis by an experienced geomorphologist or oceanographer will be enough to meet client needs.

At ABPmer we ensure that we use the right tools at the right time. When considering when and how to use numerical modelling, the following informs our decision:

What is required and why?

Every assignment we undertake starts with the end in mind, this means we make no assumptions that a model will be needed. We consider what the results will be used for and the risks associated with uncertainty; be it feasibility studies, EIA or design.

What are the physical processes that need to be understood or replicated?

Straight open coasts, pocket beaches protected by headlands or complex estuaries; the choice of modelling tool(s) will be the ones that can appropriately replicate the parameters being investigated and how they influence the local environment.

What data is available?

Building models with poor data will naturally lead to poor results, no matter how sophisticated the representation of sediment or fluid dynamics.

Where appropriate calibration data is lacking, we look to mitigate this by using multiple assessment tools and data sources. In many cases we use our calibrated regional SEASTATES models as boundary conditions for local model build, overcoming the need for local data.

What levels of uncertainty remain?

Whatever the choice of modelling tools, uncertainty will remain; whether through the limitations of the primary data or how the models are simulating the complex physics of the natural environment.

The natural environment is a highly dynamic system, with the coast responding to every tide and storm.

Model results, no matter how robust, will only ever be snapshots in time. The key to successful analysis is the interpretation of the results underpinned by a robust understanding of the physical processes of the marine and coastal environment.

The key to quality consultancy is deciding the right route to the answer and that means being proportionate in our choice of approach. We can always model the situation, but sometimes a desk-based study is all that’s needed... it all starts with 'why?'

Prepared by Heidi Roberts, Infrastructure Business Manager