A framework to quantify flow through coral reefs of varying coral cover and morphology

One of the biggest challenges we face to predict shoreline change adjacent to coral reefs is how a reef affects the flow of water close to the bed. This is important because within a coral reef canopy is where the vast majority of sand and other material is transported.

Usually, we model the transport of sand using empirical equations (there are several of them). Fundamentally, these equations rely on a shear stress (or some proxy for that) to describe the forces imposed on the the sand and thus if it will be transported or not. Normally when we predict this shear stress for coral reefs, we tune model using a friction coefficient. However, this coefficient is usually defined to get the overall hydrodynamics right (basically by representing the reef as a number). It does not consider what happens within the reef close to the bed; how the flow is attenuated by the reef. We can overcome this using methods such as CFD, however these fully 3D models require substancial computing power and are not well suited for practical large scale applications.

Over the last few years, I've been working with some great people UWA Oceans Institute on a new framework to try and describe the flow of water through coral canopies in a practical way. We found that it is possible to define a single coral parameter to explain variation of in-reef velocity across morphologies (archetypal table, massive & branching forms), reef densities, and flow depths. By integrating data of coral cover and geometry, this framework is a practical step towards the prediction of in-reef flows in diverse reef environments.

Our proposed framework was recently published in PlosOne and is Open-Access. What is exciting, is that this framework can be expanded upon by others, and can be implemented in existing numerical models fairly easily. We talk a little bit about that in our paper.

Read it here: https://lnkd.in/g_USyPGX