Effect of topography and hydrological change on solute transport at the sediment-water interface in seasonal lakes

Abstract

Study regionThe Poyang Lake is located in northern Jiangxi Province, which is the largest fresh water in China. The upstream connection with rivers and downstream access to the Yangtze River create seasonal hydrological regimes, resulting in over 100 seasonal lakes within the floodplain. These lakes provide important habitats for migratory birds to forage and nest during dry seasons, and contribute to floodwater regulation during wet seasons, maintaining lake ecosystem. Study focusThis study has combined laboratory experiments and numerical simulations to mechanically analyze the effect of the depth, width, slope of seasonal lakes, water level amplitude and dry season periods on water recharge patterns, exchange fluxes and solute transport characteristics at the sediment-water interface. New hydrological insights for the regionReducing the lake area by 33% through adjustments in depth or slope significantly reduces solute transport range (12.81% and 6.5% within 120 min) and high velocity area. The sensitivity of the solute amount in the lakebed to depth is the highest, followed by slope and width. Decreasing water level amplitude during dry seasons increases the flow velocity within the beach, facilitating short-term solute transport towards the lakebed. Extending the duration of dry periods increases cumulative flux of solutes entering the lakebed. These findings contribute to the ecological restoration efforts in floodplains and water pollution control measures.