Impact of Shelf Valleys on the Spread of Surface-Trapped River Plumes

Abstract This study focuses on mechanisms of shelf valley bathymetry affecting the spread riverine freshwater in nearshore region. In context Changjiang River, a numerical model is used with different no-tide idealized configurations to simulate development unforced river plumes over sloping bottom, and without off estuary mouth. All simulated are surface-trapped continuously growing bulges near mouth narrow coastal currents downstream. The simulations indicate that tends compress bulge along direction long axis modify incident angle flow impinging toward coast, which then affects strength current. compression results from geostrophic adjustment isobath-following tendency depth-averaged Generally, resulting change enhances down-shelf momentum advection delivery into Sensitivity altered discharges Q , Coriolis parameter, bottom slope, geometry, ambient stratification show enhancement transport current, Δ c increases increasing depth within region decreasing slope Burger number shelf. Assuming potential vorticity conservation, scaling formula / developed, it agrees well sensitivity simulations. Mechanisms influences revealed here will help future studies topographic influence under more realistic conditions.