Projections of Land Loss to Major Deltas: The Effects of Relative Sea-Level Rise and Fluvial Sediment Delivery in the 21st Century

Abstract

River deltas are currently at risk of substantial land loss due to the dual threats of RSLR and declining fluvial sediment supply. Here we use IPCC RSLR scenarios and projections of fluvial sediment supply to build a model of delta response for 47 world’s major delta. We model 9 scenarios representing four climate pathways (Representative Concentration Pathways 2.6, 4.5, and 8.5), three socioeconomic pathways (Shared Socioeconomic Pathways 1, 2, and 3), and one dam construction timeline. The model results indicate that 35 out of 47 deltas are expected to undergo a loss in the delta area by the end of the 21st century, considering the average scenario. The potential loss for the total of 47 major deltas ranges from 4,924.57 km2 for SSP 3, RCP 2.6 scenarios to 18,161.18 km2 for SSP 1, RCP 8.5 scenarios. The largest projected delta area change suggests a potential 2.78% area loss for the total of 47 major deltas. These anticipated area losses are primarily driven by the overwhelming impact of climate change-induced sea-level rise compared to the combined effects of anthropogenic activities (socio-economic factors and dam construction) and climate-change-induced fluvial sediment delivery. Notably, concerning the fluvial sediment delivery effect on relative delta area change, we find that anthropogenic activities (socio-economic and dam construction) appear to have a more significant impact on the reduction in the changes of delta area rate over time than the effect of future climate change.