Modeling deltaic response to changes in fluvial sediment delivery

摘要: River deltas are extremely dynamic and complex depositional features, shaped by marine fluvial processes. Due to growing social, environmental economic pressures, such as population growth sea level rise, understanding of these systems becomes increasingly relevant. This study aims at identifying characterizing long-term (centennial) deltaic response changes in sediment load. Two types distinguished: (i) permanent elimination the supply (ii) time periodic supply. Thus: how does shoreline a wave-dominated delta develop having time-periodic or delivery? A numerical model utilizes relation between waves littoral transport calculate displacement. Aimed studying deltas, addition somewhere along shore builds delta. (i) The directionality energy determines large extent develops after There four distinct modes which can be abandoned. A diffusive mode erodes deposits near river mouth. Higher wave direction asymmetry creates discontinuity that propagates downdrift riverine input. One spit portions shoreline. Ebro delta, Spain, is an example mode. current shape spits reveal abandonment conditions historical lobes. Large trains sandwaves before lobe characterize sandwave-mode. (ii) More regular variation input influences migrating sandwaves. frequency magnitude "forcing" initiate equal pattern migrates away from exists select range climate forcing frequencies magnitudes translation one-to-one. Longer period signals shredded autogenic-formed sand waves. Input also affects structure delta. Unstable shorelines, megadroughts influence Godavari have highly non-linear on signals. coupling with updrift deposition much simpler. Regular erosion convex beach ridges up distance determined variation. Understanding recognizing helps determine style results historical, future evolution.