Impact of mega-nourishment interventions near river mouths on upstream areas

Kumar, Pavitra ORCID: https://orcid.org/0000-0002-4683-724X and Leonardi, Nicoletta (2025) Impact of mega-nourishment interventions near river mouths on upstream areas. In: River Flow 2024. Taylor & Francis, London, pp. 638-645. ISBN 9781003475378

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Abstract

Sand engines are large-scale beach nourishment projects designed to protect coastlines from erosion and flooding. They are typically constructed as artificial islands or extensions of existing beaches and can provide decades of protection. Compared to standard nourishment interventions, sand engines can attenuate wave energy and feed sediments to nearby coastlines over a longer period. This reduces the need for frequent maintenance work, which can be costly and disruptive. However, there is still some uncertainty about the impact of sand engines on nearby areas, e.g., nearby riverine areas, including their impact on sediment transport, water levels, and wave heights. This study explores the potential effects of a sand engine located in the proximity of rivers mouths on suspended sediment transport, water level, and significant wave height within nearby rivers. Using Delft3D, the coastal and riverine system of Morecambe Bay and River Leven were simulated with and without the presence of a sand engine near the river mouth. The findings were used to train a machine learning model for predicting the impact of sand engines on suspended sediment transport and significant wave heights without the use of numerical modelling and by using a few variables as inputs.