Publications
Following publications have been announced by our department Sediment Transport and Morphodynamics. For further information please contact the marked authors of the publications:
Ma, M., Zhang, W., Chen, W., Deng, J., & Schrum, C. (2023): Impacts of morphological change and sea-level rise on stratification in the Pearl River Estuary. Front. Mar. Sci., 10:1072080, doi:10.3389/fmars.2023.1072080
Abstract:
The Pearl River Delta (PRD), where several megacities are located, has undergone drastic morphological changes caused by anthropogenic impact during the past few decades. In its main estuary, the water area has been reduced by 21% whilst the average water depth has increased by 2.24 m from 1970s to 2010s. The mainly human-induced morphological change together with sea level rise has jointly led to a remarkable change in the water stratification. However, the spatial and temporal variability of stratification in the estuary and associated driving mechanisms remain less understood. In this study, stratification in the Pearl River Estuary (PRE) in response to morphological change and external forcing is investigated by 3-dimensional numerical modeling. Simulation results indicate that stratification in the PRE exhibits distinct spatial and temporal variabilities. At a tidal-to-monthly time scale, variation of stratification is mainly driven by advection and straining through tidal forcing. At a monthly-to-seasonal scale, monsoon-driven river runoff and associated plume and fronts dominate the variation of stratification. Human-induced morphological change leads to an enhancement of stratification by up to four times in the PRE. Compared to an overwhelming human impact in the past few decades, future sea level rise would further enhance stratification, but to a much lesser extent than past human impacts. In addition, stratification in different areas of the estuary also responds differently to the driving factors. The western shoal of the estuary is most sensitive to changes in morphology and sea level due to its shallowness, followed by the channels and other parts of the estuary, which are less sensitive.
Xu, Y., Zhou, F., Meng, Q., Zeng, D., Yan, T., & Zhang, W. (2023): How do topography and thermal front influence the water transport from the northern Laotieshan Channel to the Bohai Sea interior in summer? Deep Sea Research Part II: Topical Studies in Oceanography, Volume 208, 2023, 105261, doi:10.1016/j.dsr2.2023.105261
Abstract:
Water renewal through the Bohai Strait largely dominates the water quality of the semi-enclosed Bohai Sea (BS), which connects only to the northern Yellow Sea (NYS) through the strait. Although the peak water transport through the Bohai Strait occurs in summer, the spatially averaged water residence time of the BS shows no significant decrease compared to other periods. A three-dimensional model is applied to unravel the detailed structure and dynamic processes of the summertime NYS water transport from the northern Laotieshan Channel to the BS interior. Model results from both climatological and hindcasting cases show that despite a large amount of the NYS water enters the strait, they are confined to the Laotieshan Channel between the Central Bank and Dalian surrounded by a strong Ω-shaped tidal front and could not move further north into the Liaodong Bay. The strong along-front flow steered by the topography forms a counter-clockwise circulation pattern in the strait zone, resulting in most of water southward movement east of the Central Bank, then join the outflow south of the strait and leave for the NYS. The Central Bank and the topographic sill north of the Laotieshan Channel act as a barrier that significantly reduces the water exchange between the strait zone and the BS interior, in particular the Liaodong Bay. Particle-tracking experiments suggest that less than 10% of particles released in the NYS could finally reach the BS interior, and among of them only a small portion of them could move further north into the Liaodong Bay. Momentum diagnostics suggest that the water transport northwest of the strait is dominated by geostrophic balance in the Ω-shaped frontal region. Sensitivity experiments indicate that tides promote the surface water transport from the NYS to the BS interior. The realistic wind forcing including synoptic events may facilitate the water transport from the strait to the BS interior by modulating the barotropic and baroclinic pressure gradient than that with the climatological wind case.
