Semi-enclosed bays are significantly influenced by the interactions between land and sea, as well as human activities. One notable human activity, land reclamation, impacts water exchange within these bays. However, the variability of sediment transport and cross-bay transport following reclamation remains poorly understood. This study aims to enhance the understanding of sediment dynamics and the responses of cross-bay transport to reclamation. A well-validated three-dimensional numerical model was developed in the Laizhou Bay (LB). Following reclamation, tidal currents suspended sediment concentration, and erosion increased seaward, while these factors decreased landward. In LB, surface and bottom subtidal currents flowed in opposite directions, with the direction of volume transport primarily determined by bottom currents. In the western LB, volume and sediment transport exhibited an anticyclonic pattern, with pronounced seasonal variations observed elsewhere. During summer, volume and sediment transport predominantly occurred from the northeast to the southwest. In winter, volume transport in northern LB was directed westward, while it was eastward in the southern part; sediment transport was primarily eastward. Advection played a significant role in sediment transport dynamics. The pathway of cross-bay sediment transport was primarily located in the central part of the bay. Notably, the cross-bay sediment transport flux in winter was approximately 3.5 times greater than in summer, with reclamation resulting in a reduction in cross-bay transport flux by about 22.17%.

Understanding on the spatiotemporal interactions between ecosystem services (ESs) and social–ecological drivers is crucial for the design of sustainable development strategies for coastal wetlands. In this paper, we took the Yellow River Delta (YRD) as a case study, based on multiple evaluation methods to study the spatiotemporal dynamics of ESs in the YRD from 1980 to 2020. With the help of principal component analysis (PCA) for identification of multiple drivers, we researched the spatiotemporal differentiation and influence mechanism of drivers on ESs, using the coupling coordination degree (CCD) model and geographically and temporally weighted regression (GTWR) model, and subsequently provided the development strategy for each district in Dongying City. The results showed that (1) the patterns of ESs were spatially heterogeneous, with a fluctuating upward trend from 1980 to 2020, which was mainly affected by regulating service. (2) Our spatiotemporal analysis of ES interactions identified that cultural service was mainly disorder with other ESs. Nevertheless, in wetlands, various ESs can basically develop in a coordinated manner. (3) We integrated multiple drivers into five principal components by PCA, to which the response of ESs had spatial heterogeneity. (4) Consequently, we integrated spatiotemporal knowledge on ES interactions and their drivers into spatial planning.

Tropical cyclones (TCs) play important roles in the evolution of beaches. The response of beaches to a single tropical cyclone (TC) has been well reported, however, few studies have compared the responses of the same beach to TCs with different characteristics. Taking Haiyang Beach in the northern China Seas as a case study, the beach profiles before and after two TCs, Lekima and Bavi, which passed through the west and east sides of the study area, were investigated. The beach exhibited erosion at the upper foreshore and minor deposition near the mean high water level (MHW) after Lekima with subaqueous sandbars formed in the nearshore zone, whereas all the beach profiles showed little changes after Bavi. A high-resolution FVCOM model was established and eleven sensitive experiments were conducted to simulate hydrodynamic changes induced by TCs with different tracks, intensity and duration. Then the Xbeach model was used to display the beach evolution due to different TCs conditions. It is found that the significant storm surge and strong seaward bottom current induced by landward wind of the TCs passed through the west side of the study area should responsible for the beach profile changes. Negligible storm surge rise and landward bottom current related to the seaward wind of eastern path TCs can only result in little change of the beach. Swell contributes most to the wave height while has less effect on the beach changes. In this study, we conclude that the effects of TCs on beaches are primarily dependent on relative position of a beach and TCs’ tracks.

The field of seawater desalination faces some challenges. For example, at present, site selection and layout of water intakes and outlets are often not carefully considered. This can easily result in the degradation of water quality due to coastal sea pollution and sudden brine discharge, which can be hazardous and can negatively impact marine development and activities such as aquaculture. By using the MIKE21 numerical simulation software, this paper establishes a two-dimensional mathematical tidal current model of the engineered sea area and a mathematical convection diffusion model after brine discharge. The tidal current field of the Laoshan Bay waters and the salinity field distribution after brine discharge in different water intake-outlet arrangement schemes in desalination plants are calculated and analyzed. In view of the various control factors affecting the layout and location selection of water intakes and outlets, combined with the current situation of marine development and utilization, calculation results and layout advantages and disadvantages of the primary schemes are compared and analyzed, the scheme with the best water intake-outlet layout is recommended, and relevant optimization suggestions are presented.