The Influence of Estuarine Sand Dunes on Salt Intrusion

Saltwater intrusion in estuaries can pose a critical issue with significant implications for human activities such as industry, agriculture and drinking water extraction, and can be unfavourable to environmental sustainability. This phenomenon arises when saline water infiltrates the estuarine system, potentially leading to a shortage of freshwater. The intensity of salt intrusion is influenced by various factors, of which freshwater river flushing and the amount of vertical transport in the flow are key predictors (Geyer & MacCready, 2014).

This study investigates the impact of estuarine sand dunes, bedforms with heights in the order of meters and lengths of tens to hundreds of meters (Zorndt et al., 2011), on salt intrusion. Estuarine sand dunes potentially increase the net vertical flux, by an increase in large-scale turbulence, tide-averaged circulation cells and resonant internal waves. An increase in vertical transport generally decreases stratification and reduces salt intrusion. We determine the potential of estuarine sand dunes as a nature-based solution against salt intrusion and investigate the complex salt transport dynamics over these bedforms on an estuarine scale.