Estuarine sand dunes as a nature-based solution against salt intrusion: an idealised morphostatic model approach

Saltwater intrusion in estuaries can pose a critical issue as it potentially leads to a shortage of fresh water. In turn, this can have significant implications for human activities such as industry, agriculture and drinking water extraction; also it can be unfavourable for environmental sustainability. The intensity of salt intrusion is influenced by various factors, of which freshwater river flushing and the amount of vertical transport 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 turbulence, tide-averaged circulation cells and resonant internal waves, and, as such, likely reduce the salt intrusion length. We investigate the complex dynamics of estuarine salt transport and determine the potential of estuarine sand dunes asanature-based solution against salt intrusion.