Human disturbance in the Arctic is increasing. Abrupt changes in vegetation may be expected, especially when spots without vegetation are made available; additionally, climate change alters competition between species. We studied whether 34- to 35-year-old seismic operations had left imprints on local vegetation and whether changes could be related to different soil characteristics. The study took place in Jameson Land in central east Greenland where winter seismic operations in search of oil took place from 1985 to 1989. This area is dominated by continuous dwarf shrub heath with Cassiope tetragona, Betula nana, and Vaccinium uliginosum as dominant species. Using point frame analyses, we registered vascular plants and other surface types in frames along 10-m transects in vehicle tracks (hereafter damages) and in undisturbed vegetation parallel to the track (hereafter references) at eleven study sites. We also measured temperature and pH and took soil samples for analysis. Damaged and reference vegetation types were compared with S & oslash;rensen similarity indices and detrended correspondence analyses. Although most vascular plant species were equally present in damaged vegetation and in references the detrended correspondence analyses showed that at ten out of eleven study sites the damages and references still differed from each other. Graminoids and the herb Polygonum viviparum had the highest occurrence in damages. Shrubs and the graminoid Kobresia myosuroides had the highest occurrence in references. Cassiope tetragona was negatively impacted where vehicles had compacted the snow. Moss, organic crust or biocrust, soil, and sand occurred more often in damages than in references, whereas lichens and litter had the highest occurrence in references. The richness of vascular plant species varied between the eleven study sites, but between damages and references the difference was only up to four species. Temperature was the soil parameter with the most significant differences between damages and references. Total recovery of the damaged vegetation will most likely not occur within several decades. The environmental regulations were important to avoid more serious impacts.

In mid-July 2021, a quasi-stationary extratropical cyclone over parts of western Germany and eastern Belgium led to unprecedented sustained widespread precipitation, nearly doubling climatological monthly rainfall amounts in less than 72 h. This resulted in extreme flooding in many of the Eifel-Ardennes low mountain range river catchments with loss of lives, and substantial damage and destruction. Despite many reconstructions of the event, open issues on the underlying physical mechanisms remain. In a numerical laboratory approach based on a 52-member spatially and temporally consistent high-resolution hindcast reconstruction of the event with the integrated hydrological surface-subsurface model ParFlow, this study shows the prognostic capabilities of ParFlow and further explores the physical mechanisms of the event. Within the range of the ensemble, ParFlow simulations can reproduce the timing and the order of magnitude of the flood event without additional calibration or tuning. What stands out is the large and effective buffer capacity of the soil. In the simulations, the upper soil in the highly affected Ahr, Erft, and Kyll river catchments are able to buffer between about one third to half of the precipitation that does not contribute immediately to the streamflow response and leading eventually to widespread, very high soil moisture saturation levels. In case of the Vesdre river catchment, due to its initially higher soil water saturation levels, the buffering capacity is lower; hence more precipitation is transferred into discharge.

A wharf is typically constructed as an engineering structure for loading and unloading goods. This structure may be built on weak layers of sand and gravel, depending on the beach conditions. In this way, if a wharf is poorly designed or experiences a rupture, all activities at the site might be halted for a significant period, potentially causing damage to nearby facilities. For this reason, it is of great importance to evaluate the behavior of coastal structures against rupture factors, such as earthquakes and their liquefaction effects. Generally, numerical methods are used to analyze the performance of wharves against liquefaction. This article aims to simulate liquefaction in the soil around the wharf by applying the capabilities of FLAC3D software to analyze nonlinear effective stress and generate excess pore water pressure in a continuous soil environment. The simulation was conducted using the P2PSand behavioral model, a multi-directional model, under bidirectional earthquake loading. Subsequently, the effect of various earthquake parameters on wharf behavior was investigated to extract results for excess pore water pressure, horizontal displacement, soil settlement, and bending moments of piles. Further, an attempt was made to assess the correlation of these parameters with different earthquake factors. Earthquake intensity measures are crucial in the probabilistic seismic demand assessment of various structures. Thus, this study seeks to investigate determinant indicators such as efficiency, practicality, proficiency, and sufficiency in relation to earthquake magnitude and the distance from the center of earthquake propagation to evaluate the quality of earthquake intensity measures. The results indicated good agreement between earthquake CAV parameters and response parameters.

The batter piles of a pile-supported wharf are severely damaged under excessive lateral loads, and effective reinforcement strategies are of great concern. In this paper, the effect of different reinforcement strategies on the lateral bearing performance of the wharf, taking into account the pile-soil interaction, was investigated using centrifuge test and numerical simulation. The results showed that both reinforcement strategies were effective in improving performance, with results generally aligning with those of the intact wharf in terms of load-displacement relationships, and significantly reduced the magnitudes of pile lateral deflection, soil pressure, bending moment, and shear force compared to the broken wharf. However, the concrete jacketing method resulted in larger lateral deflections in the middle sections of the retrofitted batter piles, and then abruptly reduced to match those of the steel-bonding method in the cap-pile regions. The degree of abrupt changes of bending moment in retrofitted batter piles was more distinct in the concrete jacketing wharf than that in the steel-bonding wharf. The steel-bonding method distributed the lateral load more evenly than the concrete jacketing, which involved more abrupt changes in shear forces. Overall, although the performance of both retrofitting methods was slightly better than that of the intact wharf at component level, the steel-bonding method appeared to prove superior due to the smaller change in stiffness and the more even distribution of lateral loads.

Pile-Supported Wharves (PSW) are critical for maritime operations but are highly vulnerable to seismic events, which can disrupt port activities. Previous seismic events have highlighted that short free length piles in wharf structures are particularly prone to earthquake damage. This paper aims to mitigate damage between the wharf deck and piles connections by adopting the seismic isolation systems. Conventional Wharf (CW) and Isolated Wharf (IW) structures were comprehensively assessed, focusing on Pile-Soil Interaction (PSI), using the finite element software OpenSees for advanced numerical simulations. Non-Linear Time History Analysis (NLTHA) of CW and IW has been conducted to verify the design under Contingency Level Earthquake (CLE) and Maximum Considered Earthquake (MCE) scenarios. The analysis aims to enhance the performance of short free length piles within the IW structure. Comparative analysis of fragility curves between CW and IW structures shows that isolation systems significantly reduce seismic fragility by 49%, 60%, and 67% at the MCE level for minimal damage, control & repairable damage and life safety protection across three performance levels, respectively. These findings indicate that the implementation of isolation measures has significantly enhanced the seismic performance and safety of PSW structures.

Combined with the research results of shaking table test, through the deformation performance of steel pipe pile foundation, the seismic damage and seismic performance of steel pipe high pile wharf are evaluated, and the appropriate evaluation method is given. By setting the numerical analytical model of multi working condition steel pipe high pile wharf with different water depth, different pile types and different pile diameters, the limit displacement of the pile in the soil under different ground motions is calculated. The calculated results show that, the plasticity ratio (defined as mu = delta u/delta y) of the structural system of steel pipe high pile wharf ranges from 1.5 to 3.0; and the fitting relationship between plasticity ratio mu and the diameter thickness ratio D/t was obtained. The fitting relationship is tested by the existing experimental research results. The results show that the given fitting relationship can be in good agreement with the experimental results in the range of +/- 15%. On the basis of this fitting relationship, taking the diameter thickness ratio as the basic parameter, a seismic damage evaluation method of steel pipe high pile wharf structure based on deformation performance is proposed.

The approach bridge of the pile-supported wharf is an important structure that connects the pile foundation platform and the land, and it has a significant impact on the safety of the high-pile wharf. However, the influence of an approach bridge on the seismic dynamic response of a pile-supported wharf has often been neglected in previous studies. Besides, the excess pore water pressure (Delta u) generated under combined vertical and horizontal seismic components is typically greater than that induced by unidirectional excitations, which may further impact the dynamic response of pile-supported wharf. Firstly, this study developed a numerical method for simulating the approach bridge of a pile-supported wharf. Secondly, the three-dimensional finite element model of a pile-supported wharf with an approach bridge is established to investigate the dynamic response during horizontal and vertical seismic components. Additionally, the effects of seismic frequency and relative density of liquefied layer on the dynamic response of pile-supported wharf were also studied. By comparing with the experimental results, the numerical model effectively simulated the overall response of the pile-supported wharf and the liquefaction behavior of the surrounding soil. During high-frequency earthquakes, the influence of the approach bridge on the dynamic response of the pile-supported wharf is minimal, whereas it has a more significant impact during low-frequency earthquakes. Furthermore, vertical seismic components significantly amplify the effect of approach bridge on the lateral displacement and internal forces of piles. The effect of the approach bridge on the lateral displacement and internal force of the pile decreases with the increase of the relative density of the liquefaction layer.

The soft soil foundations of gravity wharves are subject to the wharf weight and wave forces, and the deterioration of the wharf soil foundation strength under such cyclic loading affects the structural safety of gravity wharves. This study investigated the weakening characteristics of soft soil strength. Undrained triaxial tests were conducted on undisturbed saturated soft soil specimens under isotropic consolidation conditions, and a dynamic finite element model of the wave-gravity-structure-soft-soil-foundation interaction was established. The results indicated that the shear modulus of the soil was related to the effective confining pressure and shear strain; this relationship was fitted using the Van Genuchten equation. As the internal friction angle of the soft-soil foundation decreased, its stability decreased nonlinearly, the strength decreased, and the sliding failure surface expanded. Simply increasing the riprap layer thickness had a limited effect on the overall wharf stability. These findings will guide the design of gravity wharves with foundations on soft soils in port areas that are subjected to intense wave actions.

Since the 1970s, China has continuously improved air pollution treatment and emission standards, but polluted weather still occurs frequently in some areas, especially haze weather. At present, most of the research on haze weather focuses on particulate matter, while ignoring the mechanism of aerosol-radiation-surface ozone interaction under haze weather. Therefore, this paper analyses the relationship between aerosol-radiation-surface ozone with the help of the (SBDART) model for the Guangdong-Hong Kong-Macao Greater Bay Area (GBA), using 2013-2021 as the time line. The results show similar trends in total column ozone and tropospheric ozone, and separate trends in surface ozone. Total column ozone and tropospheric ozone concentrations are at high values in spring and summer and low values in fall and winter; surface ozone is higher in summer and fall and lower in winter and spring. In contrast, Absorbing aerosol index (AAI) had high values in both spring and winter, and low values in summer and autumn. AAI, PM10 and Black carbon (BC) showed negative relations with ozone overall, but AAI and tropospheric ozone reached high values simultaneously in spring, indicating a rapid increase of pollutants caused by meteorological factors and human activities. Ozone concentration decreases from high values when precipitable water increases significantly. The analysis of potential sources of AAI indicated that local sources centered in Guangzhou were the primary source of AAI in the urban agglomeration of GBA, while other potential sources include biomass sources in the south and ozone sources in the northeast. The photolysis rate of fine-grained urban/industrial aerosols did not decrease significantly, leading to an increase in surface ozone concentration. Therefore, low aerosol radiative forcing (ARF) may increase surface ozone concentrations in the fine-particle aerosol mode.

The gravity -type wharf is generally more vulnerable during earthquakes due to its massive gravity quay wall, especially when located in a liquefiable area. Therefore, this study aims to develop numerical analysis procedure for its seismic performance assessment and fragility analysis considering the influence of soil liquefaction. Firstly, the quantitative damage criteria for gravity -type wharves were introduced and verified by case histories. Then, the finite element (FE) modeling of a gravity quay wall founded on liquefiable ground for seismic response analysis using PLAXIS 2D was suggested. Utilizing this modeling, the earthquake -induced damage cases of two gravity -type wharves in two ports in Taiwan were simulated for validation. The seismic performance of both wharves was further assessed by comparing the analyzed response under design earthquake with the damage criteria. Finally, the procedure of seismic fragility analysis based on massive numerical analysis was proposed. Actual earthquake records were scaled to various seismic intensity levels to serve as input motions. Thus, the relationships between the seismic intensity and the damage probability of a gravity -type wharf corresponding to different damage levels, namely, the fragility curves, can be accordingly obtained. These results benefit the seismic performance design and rapid estimation of possible seismic damage of port facilities.