Multi-scale morphodynamics of an estuarine beach adjacent to a flood-tide delta: Assessing decadal scale erosion

Wave direction shift triggered severe erosion of beaches in estuaries and bays with limited post‐storm recovery

“…Note that we also explored changes in alongshore shoreline orientations using the method of Harley et al (2015), but there were no clear trends so these data are not shown here. In addition, Harris et al (2020) showed that beach rotation is generally not important on BEBs because any swell always propagates from the same direction as allowed by the estuary/bay mouth orientation.…”

“…Estuarine and bay coasts are widespread and densely populated (Eliot et al, 2006;Vila-Concejo et al, 2010;Harris et al, 2020). A ubiquitous feature of estuaries and bays is sandy beaches (Vila-Concejo et al, 2020), which can be small in scale when compared with open coast beaches.…”

“…BEBs are sometimes also referred to as low-energy beaches (Jackson et al, 2002; Vila-Concejo et al, 2020), fetch-limited beaches (Jackson et al, 2002;Nordstrom and Jackson, 2012), bayside beaches (Nordstrom, 1980;Ekwurzel, 1990), sheltered beaches (Hegge et al, 1996;Travers et al, 2010) and tide-dominated beaches (Masselink and Short, 1993;Short, 2006). The lack of understanding of BEB morphodynamics is a critical issue with climate change, as it exacerbates uncertainties and vulnerability (Vila-Concejo et al, 2010;Nordstrom and Jackson, 2012;Harris et al, 2020).…”

“…Meanwhile, Nordstrom (1980), Nordstrom et al (1990), Jackson and Nordstrom (1992) and Nordstrom et al (1996), among other works such as Rosen (1977) and Rosen (1980), focused largely on beaches in estuaries and bays in north-eastern USA. Studies in other parts of the world include Ría de Vigo (Costas et al, 2005;Bernabeu et al, 2012), Sydney Harbour (Kennedy, 2002) and Port Stephens (Vila-Concejo et al, 2010;Harris et al, 2020), among others. Research in these few locations suggests that BEBs tend to be narrow and steep (Jackson and Nordstrom, 1992;Suhayda and Oivanki, 1993), planar (Nordstrom, 1980;Hegge et al, 1996) with no offshore bars or rhythmic topography (Kennedy, 2002) and with no backshore (Jackson et al, 2002).…”

Decadal shoreline erosion and recovery of beaches in modified and natural estuaries

“…Rather, it appears that beaches typically protected from swell recover at slower rates than open coast beaches (Costas et al, 2005). Previous BEB studies have focused largely on timescales of months to a few years (Gallop et al, 2020;Harris et al, 2020;Vila-Concejo et al, 2010) and it is not known if BEBs can recover fully over longer timescales -or if erosion is a one-way process for some BEB settings, leading to progressive shoreline retreat (Harris et al, 2020). For example, sediments eroded from BEBs can be transported to nearshore sediment sinks, such as flood-tide deltas/shoals (Austin et al, 2018;Vila-Concejo et al, 2011;Vila-Concejo et al, 2007).…”