Sediment gravity flows drive the buildup of the modern Huanghe (Yellow River) delta front

Abstract

The rapid development of the delta front is heavily influenced by sediment gravity flows (SGFs), posing significant challenges to coastal infrastructure. Accurately assessing the long-term impacts of SGFs—triggered by river floods, slope failures, and wave activities—on delta front geomorphology and sedimentation patterns remains a complex task. This complexity is heightened during the formative stages of delta development, where distinguishing between the contributions of different SGF triggers is particularly challenging. To address this, we employed the forward stratigraphic model Sedflux-2D, integrating key input parameters, such as initial bathymetry, river discharge, suspended sediment concentration, and wave height, based on observed values. The model was calibrated against seismic stratigraphy and sediment core grain size data to reconstruct the annual-to-decadal evolution of the modern Huanghe Delta (MHD). By comparing the simulated outputs with present-day bathymetry and grain size distributions, we quantitatively evaluated the impacts of SGFs driven by primary factors such as wave energy, river discharge, and slope stability on MHD front development. Our findings reveal that, during the transition from nearshore to offshore environments, sediment grain size distribution within the delta strata is predominantly controlled by SGFs driven by waves, river fed, and collapses. Hyperpycnal flows, generated by river floods, contribute significantly to deltaic sediment dynamics, accounting for approximately 20 % of total sediment volume and 30–50 % of foreset progradation over sub-decadal to decadal timescales. Collapse-induced SGFs, meanwhile, are responsible for approximately 25 % of foreset sediment volume loss, influencing bottomset development beyond 10 m water depth. These findings highlight the critical role of hyperpycnal flows in shaping the MHD front. This study integrates forward simulation with inverse sediment record analysis, providing a robust framework for quantifying the contributions of SGFs to delta front development. The comprehensive insights gained from this approach are essential for informed decision-making in delta management.