Dataset for article: "Viability of beach nourishment as a long-term strategy for maintaining beaches in bays and estuaries"

Datasets associated with: Viability of beach nourishment as a long-term strategy for maintaining beaches in bays and estuaries (Submitted for review: Feb 2025) Funding: Department of Energy, Environment and Climate Action, Victoria, Australia Authors: Oliver Dalby-1, Robert J. McCarroll-2*, David M. Kennedy-2 and Daniel Ierodiaconou-1 1 School of Life and Environmental Sciences, Deakin University, Warrnambool, Victoria, Australia 2 School of Geography, Earth and Atmospheric Sciences, The University of Melbourne, Carlton, Victoria, Australia * Corresponding author: Robert Jak McCarroll, [email protected] Abstract Beach nourishment is a widely used coastal adaptation strategy, though for some coastlines, debate exists as to its long-term viability to offset the impacts of sea level rise, due to limited sediment sources and negative environmental impacts. For beaches in bays and estuaries, in contrast to the open coast, wave energy is lower, decreasing required nourishment volumes, and bay shorelines around large cities are often already extensively disturbed. We examine whether nearshore-sourced beach nourishment is a viable long-term option for a range of lower energy shorelines across Port Phillip Bay, Australia. Sand volumes were estimated from sub-bottom profiling (75 km of shoreline to 2 km offshore) and grain size was compared against beaches. Shoreline recession was estimated for 1 m sea level rise to 2100, applying a high-end ‘Bruun’ response (likely on moderate energy shorelines), and a low-end ‘Beachface’ response (very low energy beaches). Offset nourishment volumes to maintain present-day beach width were calculated. Available sand volumes substantially exceeded projected offset nourishment volumes for 4 out of 5 zones. Moderate energy shorelines had sandbodies sufficient for long-term nourishment (4000 – 5000 m3/km/year; < 20% of available volume required). For low energy beaches, sediment volumes were plentiful but may be less viable due to higher mud content. A comparison between long-term nourishment requirements of open coast and bay beaches estimates 40 – 90% less sand is required for bay beaches, due to reduced shoreface extent. Accordingly, coastal managers should consider incorporating long-term beach nourishment into nature-based adaptation strategies for bay and estuarine coastlines.