Dr. Arshad Rawat

Dr. Arshad Rawat   |Clyto Access

Mauritius Oceanography Institute, Mauritius

Organizing Committee Member

Expertise: Physical oceanography, Ocean hydrodynamics, SST, Wave climatology, Coastal vulnerability, Tsunami inundation preparedness and bathymetry

Biography:

Dr. Arshad Rawat is an Associate Research Scientist at the Mauritius Oceanography Institute. He holds a PhD. in Physical Oceanography with specialization in Wave Modelling and a Masters in Mechanical Engineering with Mathematical Modelling. His aim is to apply know-how in the field of wave modeling to the development of sustainable marine energies and in disaster management. He has been working in the department of physical/satellite oceanography/GIS at the Mauritius Oceanography Institute since 2008. His principal projects include the Mauritian Continental shelf submission, ocean hydrodynamics, SST, wave climatology, coastal vulnerability, tsunami inundation preparedness and bathymetry.

Presentation:

Title: Modelling of waves, lagoonal hydrodynamics and beach erosion at Flic-en-Flac

Abstract:

Swell and wind waves are the primary forcing for the hydrodynamics within reefed lagoons, particularly those with low tidal ranges as in Mauritius. Hence they can be the primary driver for near-shore processes including the morphodynamics inside such lagoons. During the past two decades, erosion has been heavily impacting the beaches of Flic-en-Flac on the western coast of Mauritius. It has been suggested that the degradation of the fringing reefs is one of the main causes although this has not been properly studied. Here we propose to explore the effects of wave action on the morphodynamics inside the Flic-en-Flac lagoon using a nearshore numerical model.
We use a surfbeat modelling approach with sediment transport to assess the natural coastal response during normal and hurricane conditions. Surfbeat models are basically shallow-water models forced on the primary wave group scale. This type of numerical model is computationally efficient since individual short waves don’t need to be resolved. It is therefore adapted to the scale of the whole lagoons such as Flic-en-Flac. The hydrodynamics is examined using linear shallow water equations, taking into account the presence of bottom friction principally due to coral reef, the infragravity wave response, tidal modulations, setup of the mean water level and the induced longshore currents. The bathymetry being used inside the lagoon was established in 2009 by the Mauritius Oceanography Institute. This was complemented by additional datasets from aerial ocean-color imagery as well as drone stereo-imagery. Outside the lagoon, Admiralty hydrographic charts were used, up to the forcing boundary. 
Several wave forcing scenarios were examined and the effect of reef degradation was investigated. Validation was carried out using field data for coastal hydrodynamics and erosion assessment, and also through shoreline evolution investigated from remote sensing.
 

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