Atmospheric pressure disturbances of high translational speed can excite significant water waves, which are widely believed to be the main cause of destructive meteotsunamis. During the response of sea surface to adisturbance, energy is transferred from the atmosphere to the ocean, while the forced wave induced by the disturbance gradually grows and finally reaches a quasi-steady state. This study aims at quantifying the time required to excite the forced wave. Based on the nonlinear shallow water wave model, the evolution of the forced wave is numerically investigated. Analyses of the accumulation of wave energy are imported to help understand the evolution of the forced wave in different situations. The characteristics of energy accumulation show a great difference in the cases of different Froude number Fr. A parameter named response time is defined to quantify the time required for the evolution of the forced wave. It can be seen that Fr is the principal parameter that controls the wave evolution, while the effects of nonlinearity and bottom friction are significant only when Fr is close to 1. Simple relationships are proposed to roughly estimate the response time for Fr1.1, which can also provide a lower limit for Fr≈1.

Quantitative probability has been computed for the tsunami hazard posed by earthquakes from the Manila Trench, which has been regarded as a huge threat in the South China Sea. This study provides a spatial distribution of the tsunami hazard covering the affected area with a spatial resolution of 0.1° for disaster prevention of islands and continental coasts. The quantitative probability of the tsunami hazard is computed by an efficient model, which can realize a large amount of potential tsunami scenarios analysis in order to consider the randomness and uncertainty in earthquake magnitude, source location and focal depth. In the model, for each potential tsunami scenario, the occurrence probability of the corresponding earthquake and the intensity of tsunami waves at each target location are computed. The occurrence probability of each scenario is estimated based on the historical earthquake records. Then, the subsequent tsunami caused by each scenario is computed using a new, efficient approach, instead of direct simulation using an ocean dynamics model. A total of 1,380,000 scenarios are computed in order to obtain a stable statistical result. Based on the results, the spatial distribution of the tsunami hazard is discussed and high-hazard regions along the coast have been identified.

The coast around the Abandoned Yellow River Delta underwent significant changes under anthropogenic disturbance. This study aims to reveal the variation of the coastline, tidal flat area, and intertidal zone slope before, during, and after extensive reclamation during the period of 1984–2019 using satellite remote sensing images. In order to eliminate the influence of the varying water level, a new coastline correction algorithm had been proposed under the condition of insufficient accurate slope and water level data. The influence of seawalls on slope estimation were considered in it. The spatiotemporal evolution of coast had been analyzed and confirmed to be reasonable by comparing with the observed data. The results show that the coast can be roughly divided into a north erosion part and a south deposition part. Affected by reclamation, their tidal flat area in 2019 is reduced to only 43 and 27% of original area in 1984, respectively, which results in a continuous decrease in the tidal flat width. The adjustment of the tidal flat profile makes the slopes steeper in the erosion part, while the slopes in the deposition part remain stable. The reclamation has stimulated a cumulative effect as the disappearance of the intertidal zone, which may lead to the destruction of biological habitats.