The present study investigates the temporal and spatial variation of storm surge activity at different temporal scales using reconstructed daily maximum storm surge levels in the southeastern coastal area of China for the past 60 years. Considering the surge height and the duration of storm surge, the comprehensive intensity of storm surge is proposed, namely Accumulated Storm Surge Potential Impact. The results show that with the intensification of climate warming, the intensity has increased rapidly, although the overall the frequency and duration of storm surges have not changed significantly. In relation to the spatial distribution of storm surge intensity, storm surge at different time scales (interannual and decadal) was mainly located in the areas of concentration of historical tropical cyclones landing and in subconcentration areas. In terms of climate change response, it is clear that the frequency, duration, and intensity of storm surges have increased significantly since the end of the 1980s. From the perspective of the spatial distribution of the climate tendency rate (it reflects the change trend of regional climatic elements) of storm surge intensity, the areas of increased intensity are mainly located in several concentrated areas where storm surge events occur frequently, while the weakened areas are also other areas where storm surges have rarely occurred. El Niño‐Southern Oscillation events have a certain effect on the frequency, duration, and intensity of storm surge activity, although the effect on intensity is more significant. The impact of the Pacific Decadal Oscillation on the frequency, duration, and intensity of storm surge activity at different phases was also different, with clear regional distribution features for each phase. In this way, we can make targeted preparations for disaster prevention and mitigation, and avoid further socio‐economic losses.

The Three Gorges Project is the largest water conservancy project in the world. To cope with the ecological problems of the subsidence zone in the Three Gorges Reservoir area, the Kaizhou water-level-regulating dam was built, forming a model of nested water conservancy projects. The Pengxi River Basin is affected not only by this project but also by human activities in the reservoir area and changes in the substratum and hydro-meteorology, which exert influences on the water connotation function and its ecological value through complex mechanisms. In addition, the response mechanism of the changes in the environment is unclear. Therefore, based on the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model and a spatial interpolation method, in this study, two time nodes (2005 and 2018) before and after the operation of the nested water conservancy projects began were selected, and seven simulation scenarios with different water levels, precipitations, and temperatures were created to explore the evolution of the water conservation service function in the nested water conservancy project operation area under the complex changes in the environment. The results reveal that the operation of the water conservancy projects has had some influence on the water content, but the response of the water content function to the precipitation conditions has been more significant. In colder and rainier years, the water content was higher. In contrast, the lowest value occurred in a year with high temperatures and low rainfall. The highest and lowest values were quantitatively different. Therefore, the influences of the complex environmental factors on the regional water connotation service function deserve more attention. The results of this study provide a scientific basis for research on the ecological service function and the value of water conservation in the Three Gorges Reservoir subsidence zone and the nested operation area of the related water conservancy projects, as well as a data reference for the optimal allocation of regional water resources.

It is a very difficult task to analyze the spatial and temporal variability of storm surge activity with current monitoring methods, because tide gauge observation, satellite altimeter, and numerical simulation do not ensure sufficient spatial and temporal resolution and temporal coverage at the same time. We propose to use a reanalysis data set, which covers the period from 1958 to 2016, to statistically reconstruct the daily maximum storm surge levels in the southeastern coastal area of China. Then, we used the Geographical Differential Analysis (GDA) calibration to correct the reconstruction results. The verification of the statistical model and the calibration results show that both the statistical model and the GDA calibration have a good accuracy in terms of high correlations and small errors. However, they also reveal a variable spatial quality of the multivariate statistical model in the reconstructed maximum storm surge levels, especially in the extreme events of the storm surge activity, the daily maximum surge is often underestimated. The GDA calibration result readily solves this problem, as it can accurately reflect not only the daily maximum storm surge levels but also the whole spatial and temporal dynamic storm surge evolution process. Therefore, this work provides an effective method to establish long‐term sequence and high‐precision daily maximum storm surge levels. This method can reveal the spatial and temporal evolution features of storm surge intensity at a climatic scale and main variability features. Moreover, it can predict possible trends in the geospatial distribution pattern of storm surge intensity in the context of future climate change.

In the context of promoting high-quality development of mountainous urban areas, it is of great significance to explore the evolutionary trajectory of habitat quality in the future based on policy-driven backgrounds, particularly for the protection of the Western mountainous ecosystem. This study takes the Chongqing metropolitan area, a typical southwestern mountainous city, as the study area. Based on land use data from 1990 to 2020, the study combines the InVEST and PLUS models, considering the constraints imposed by urban construction planning and ecological control policies, to investigate the spatiotemporal variations of habitat quality from 1990 to 2030. The findings are as follows: (1) From 1990 to 2020, there was a significant decrease in cultivated land area in the study area, while forestland and unused land showed a declining trend. Conversely, built-up land, grassland, and water bodies exhibited an increasing trend. In the land use simulation for 2030, under the scenarios of natural growth and ecological protection, the cultivated land area further decreased, while forestland and grassland received a certain degree of protection. In the scenario of development, a large amount of cultivated land was converted into built-up land. (2) From 1990 to 2030, significant overall habitat quality changes were observed among different regions within the study area. Except for Nanchuan District and Qijiang District, other administrative regions experienced a certain degree of decline in habitat quality. The distribution of habitat quality exhibited significant spatial heterogeneity. The low-value habitat areas were centered in the middle of the metropolitan area and gradually expanded outward. The high-value habitat areas were concentrated in the study area, including the Huaying Mountain range and other mountainous ecological corridor regions. (3) Habitat quality in the study area showed a decreasing trend with an increasing slope gradient. With the development of urbanization, habitat quality degradation gradually spread to high-altitude and steep-slope areas. (4) The expansion of built-up land is the main cause of habitat degradation in the study area. From 1990 to 2030, against the background of development strategies in the study area, the expansion of built-up land encroached upon cultivated land and forestland. In the habitat quality prediction for 2030, habitat degradation in the region will continue to intensify. This study provides scientific references and the basis for promoting regional sustainable land use and ecological conservation.

The aim of the present study was to assess the suitability of mountainous areas for construction land on the basis of landslide susceptibility, to obtain the spatial distribution pattern of said suitability and to improve the existing theories and methods used to ascertain said suitability. Taking Hechuan District in Chongqing as the research area and using data relating to 754 historical landslide sites from 2000 to 2016, we selected 22 factors that influence landslides. The factors were classified into five types, namely topography and geomorphology, geological structure, meteorology and hydrology, environmental conditions and human activities. A landslide susceptibility model was constructed using the random forest algorithm, and safety factors of construction land suitability were established according to the results of landslide susceptibility, with the suitability of land for construction in mountainous areas assessed by combining the key factors (natural, social and ecological factors). The weights of the factors were determined through the use of expert approaches to classify the suitability of land for construction in the research area into five levels: prohibited, unsuitable, basically suitable, more suitable and most suitable. The results of the study show that: (1) The average accuracy of the tenfold cross-validation training set data of landslides reached 0.978; the accuracy of the test set reached 0.913; the accuracy of the confusion matrix reached 97.2%; and the area under curve (AUC) values of the training set, test set and all samples were 0.999, 0.756 and 0.989, respectively. Historical landslide events were found to be mostly concentrated in highly susceptible areas, and the landslide risk level in Hechuan District was mostly low or very low (accounting for 76.26% of the study area), although there was also a small proportion with either a high or very high risk level (9.25%). The high landslide susceptibility areas are primarily concentrated in the southern and southeastern ridge, in the valley and near water systems, with landslides occurring less frequently in the gentle hilly basin. (2) The suitability of land for construction in mountainous areas was strongly influenced by landslide susceptibility, distance from roads and distance from built-up areas; among such parameters, rainfall, elevation and lithology significantly influenced landslides in the region. (3) The land suitable for construction in the study area was highly distributed, mainly in urban areas where the three rivers meet and around small towns, with a spatial distribution pattern of high in the middle and low on both sides. Furthermore, the suitability of land for construction in Hechuan District was found to be primarily at the most suitable and more suitable levels (accounting for 84.66% of the study area), although a small proportion qualified for either the prohibited or unsuitable level (accounting for 15.72%). The present study can be extended and applied to similar mountainous areas. The landslide susceptibility map and construction land suitability map can support the spatial planning of mountainous towns, and the assessment results can assist with the development direction of mountainous towns, the layout of construction land and the siting of major infrastructure.