Sea breezes have a significant influence on the urban environment of coastal cities. Therefore, the study of the sea breeze cooling range and its relationship with specific humidity is of great significance for improving the urban environment of coastal cities. This study aims to reproduce the climate of Sendai using the regional Weather Research and Forecasting (WRF) model, clarify the influence range of sea breezes in Sendai, and create an urban environmental climate map. The results revealed a strong correlation between the measured temperatures and the calculated results, and that the cooling effect range of sea breezes was mainly concentrated in the coastal area. In addition, the temperature rise mitigation effect changed over time, and although the maximum mitigation effect range affected a part of the urban area, it did not reach the inland area. In comparison, the specific humidity increased over time from the coastal area to the inland area. It was found that sea breezes mainly affected a part of the urban area and coastal areas in terms of temperature, but affected inland areas in terms of specific humidity. The results show that the range of the cooling effect of sea breezes on temperature was only concentrated within 5 km of the coast; in terms of moderating the temperature rise, there was an effect within the area ~7 km from the coast. In terms of humidity, the effect of sea breezes occurred approximately 1 h later than the effect of temperature.

Due to global warming and urbanization, high-temperature events—which frequently occur in cities—are presenting an increasing threat to the daily lives of human beings. In coastal cities, sea breezes can cool the near surface and improve the urban environment to some extent. Understanding the cooling characteristics of sea breeze on the urban environment is informative for improving and mitigating the urban heat island (UHI) effect. In this paper, we analyze the basic characteristics of the timing of the cooling effect of sea breeze in urban summer based on the long-term multi-point measurements of air temperatures. Additionally, the Weather Research and Forecasting (WRF) model is used to show the influence of sea breeze on cities in terms of the cooling action time. The whole process is reproduced based on a time distribution map created using the results of the WRF simulation. The measured temperature and WRF simulation results are also evaluated with observations. The results show little difference between the two. The analysis of the distribution map shows that the sea breeze gradually penetrates inland from coastal areas. It can therefore be concluded that the sea breeze blows at different speeds in different areas. Our results show that the sea breeze is weak in places near the coast, while it is significantly stronger around inland rivers. Moreover, in urban areas that are far from inland rivers, the speed of the sea breeze is evenly distributed in space. The spatial pattern of sea breeze retreat time and arrival time is reversed: retreats happen earlier in inland areas. The duration of the sea breeze shows a significantly decreasing trend from the coast to inland, with the longest duration at the southern end of the urban area near the coast.

Amid intensifying global climate change, coastal cities are facing increased heat stress. The sea breeze plays a crucial role in mitigating the urban heat island effect and improving outdoor thermal comfort, warranting detailed investigation of its spatiotemporal impacts. This research, conducted in Sendai, Japan, combines the Weather Research and Forecasting (WRF) model with the Rayman thermal comfort model to assess the spatiotemporal evolution of the Physiological Equivalent Temperature (PET) on typical sea breeze days, exploring heat stress patterns. The findings indicate significant PET reductions in the area due to sea breeze influence, although high heat stress persists in urban centers. The coastal zone (0–4 km) experiences the longest period of low heat stress, whereas the inland zone (20–26 km) suffers from poor thermal comfort. Heat stress intensifies in the northwestern inland regions, while improvement progresses from the coast inland. Vegetated areas reach low heat stress states earlier than built-up areas; both coastal and urban zones quickly revert to “no heat stress” conditions. The results demonstrate that the cooling effect of sea breezes decreases with distance, its efficacy hindered by urban environments, whereas vegetated lands prolong comfort inland. These insights are crucial for planning thermal environments in coastal cities.

Summer sea breezes provide cooling in coastal cities; however, their temporal cooling distribution and inland penetration distance remain inadequately studied. This study employed the mesoscale Weather Research and Forecasting (WRF) model to analyze the sea breeze cooling capacity (SBCC) in detail. The results identified the distance from the coast, cooling timing, and proximity to inland rivers as key factors influencing the SBCC. The cooling range and intensity of sea breezes exhibited a temporal pattern, initially increasing and then decreasing, with the rate of increase significantly exceeding the decline. The maximum cooling range (277.44 km²) and strongest cooling intensity (37,989.61 °C.h) occurred at 10:00. Between 11:00 and 14:00, the cooling effect remained stable over its longest inland distance (16.2 km). The SBCC intensified notably closer to the coastline. Furthermore, inland rivers significantly enhanced the cooling effect, with the sea breeze penetration distance correlating positively with the proximity to these rivers. A detailed analysis of the SBCC’s spatial extent and cooling distance provides a crucial basis for effectively mitigating urban heat in coastal cities.

Sea breezes alleviate coastal heat stress via cooling and humidifying. Sendai, Japan, in 2015 had a population of 1.08 million and an area of 786 km². Integrating the WRF model with RayMan, this study employs the PET index to assess spatiotemporal distributions of thermal comfort and heat stress, and their influencing factors, on typical summer sea-breeze days in Sendai, Japan. Results indicate that in the coastal zone, PET was primarily regulated by air temperature (Ta) and relative humidity (RH). In contrast, wind speed was the dominant influence on urban/inland zones, with Ta and RH contributing more during the evening. Sea breezes markedly improved the thermal environment in the coastal zone, suppressing PET increases. PET in urban and inland zones exhibited an initial rise followed by a decline, with the inland zone experiencing sustained extreme heat stress for 3 h. Among regions experiencing extreme heat stress, inland zones showed the highest proportion (17.75%), while coastal zones had the lowest (2.14%). Proportions across the three zones were similar under nighttime conditions with no thermal stress, with the urban zone exhibiting a slightly lower proportion. This study provides a theoretical basis for climate-adaptive urban planning leveraging sea breezes as a resource.

Cutoff walls are used to reinforce embankments to prevent instability induced by reservoir seepage during water level fluctuations. This paper analyzes the stability enhancement provided by cutoff walls using the framework of limit analysis upper-bound method combined with a rotational log-spiral failure mechanism. Verification on unreinforced slopes shows that there is a high degree of consistency between the proposed upper bound results and existing analytical and numerical solutions. It was shown that the slope has a higher safety factor as the stabilizing effect of the cut-off wall strengthens. In addition, the critical sliding surface tended to be shallower with an increase in the external water level coupled with a decrease in the internal water level. Due to combined stabilization from soil self-weight and hydrostatic pressure, the stabilizing effect of the cutoff wall is not always necessary under all water level conditions; only when the wall is positioned within a critical normalized distance from the crest could the reinforcing effect of the cutoff wall be fully exerted.