Sediment Resuspension Under Wind-Driven Currents and Waves: 1D Numerical Simulations Guided by Direct Observations Along the Dead Sea Shore

Resuspension of fine-grained bottom sediment under wind-driven currents and waves is a key process in shaping nearshore environments. Commonly, resuspension is quantified for predicting the dispersion of contaminants and nutrients affecting water quality by numerical modeling and field measurements. Although a large body of research deals with this topic, unique field observations from hypersaline environments coupled with conceptual-quantitative description of the process are lacking. Here, we present high-resolution direct measurements of winds, waves, currents, and turbidity conducted along the Dead Sea shores and derivations of an integrated 1D-numerical model based on mass and momentum conservation laws. Comparing the model predictions and the observations determine, for the first time, that depth-averaged turbulent viscosity during Dead Sea storms is of order of 10⁻³ m² s⁻¹. Resuspension of bottom clay to fine sand is governed primarily by waves inducing shear stress three orders of magnitude larger than current-induced shear stress, a ratio which is rather constant during Dead Sea storms. The observed spatiotemporal turbidity pattern is reproduced and accounts for the effect of grain-size distributions on the lake floor. Additionally, we highlight the importance of wave-induced resuspension as an additional source of sediment involved in the formation of thin, muddy layers that are traditionally interpreted as indicators of inflowing sediment plumes. The novelty of the manuscript lies in the combination of rare observations and modeling, which provides comprehensive physics of the studied processes, an approach that can be used in other nearshore environments of lakes or oceans.