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Mangrove wetlands are hotspots of global biodiversity and blue carbon reserves in coastal wetlands, with unique ecological functions and significant socioeconomic value. Annual fine-scale monitoring of mangroves is crucial for evaluating national conservation programs and implementing sustainable mangrove management strategies. However, annual fine-scale mapping of mangroves over large areas using remote sensing remains a challenge due to spectral similarities with coastal vegetation, tidal periodic fluctuations, and the need for consistent and dependable samples across different years. In previous research, there has been a lack of strategies that simultaneously consider spatial, temporal, and methodological aspects of mangrove extraction. Therefore, based on an approach that considers mangrove habitat, tides, and a semantic segmentation approach, we propose a method for fine-scale mangrove mapping suitable for long time-series data. This is an optimized hybrid model that integrates spatial, temporal, and methodological considerations. The model uses five sensors (GF-1, GF-2, GF-6, ZY-301, ZY-302) to combine deep learning U-Net models with mangrove habitat information and algorithms during low-tide periods. This method produces a mangrove map with a spatial resolution of 2 m. We applied this algorithm to three typical mangrove regions in the Beibu Gulf of Guangxi Province. The results showed the following: (1) The model scored above 0.9 in terms of its F1-score in all three study areas at the time of training, with an average accuracy of 92.54% for mangrove extraction. (2) The average overall accuracy (OA) for the extraction of mangrove distribution in three typical areas in the Beibu Gulf was 93.29%. When comparing the validation of different regions and years, the overall OA accuracy exceeded 89.84% and the Kappa coefficient exceeded 0.74. (3) The model results are reliable for extracting sparse and slow-growing young mangroves and narrow mangrove belts along roadsides. In some areas where tidal flooding occurs, the existing dataset underestimates mangrove extraction to a certain extent. The fine-scale mangrove extraction method provides a foundation for the implementation of fine-scale management of mangrove ecosystems, support for species diversity conservation, blue carbon recovery, and sustainable development goals related to coastal development. [ABSTRACT FROM AUTHOR]

Instantaneous precipitation can often cause devastating disasters on the Earth's surface. Continuous increases in extreme precipitation around the world have caused widespread concern, and it is necessary to study the extreme hourly precipitation over a large scale and long time series. Using specific numbers of unique hourly precipitation point data from 1980 to 2019, our research found that there are different spatial patterns regarding the frequency and intensity of extreme hourly precipitation in Mainland China, but the clear spatial pattern of being weak in the west and strong in the east of China. Most extreme hourly precipitation events occurred from June to August in the north of China and from April to October in the south of China. Afternoon and midnight are the peak periods of extreme precipitation events in southern China. The frequency of extreme hourly precipitation in the whole of China had increased by 0.7 hr/10a and increased significantly in the northwest and southeast of China. The average intensity of extreme hourly precipitation has decreased by 0.1 mm·hr−1/10a in the whole of China. While the maximum intensity has increased in local areas, the trend of changes is not significant in the whole of China. We have discovered that rapid urbanization is likely to be responsible for the frequency of extreme hourly precipitation in China. It is urgent to enact flood protection measures because this change is expected to worsen in the future with intensified urbanization in China. [ABSTRACT FROM AUTHOR]

Wetland cities were proposed by the International Wetland Convention Organization for the protection of urban wetlands. Few studies have performed land cover classifications for internationally recognized wetland cities or explored what contribution the classification results can make to the establishment of additional wetland cities to date. Based on Sentinel-1 and 2 data, this study used a 10-fold random forest method to classify the land cover of the first six wetland cities recognized in China. A land cover dataset, which had a resolution of 10 m and included four wetland types, was obtained and the wetland area and protected wetland areas of the six cities were calculated. The results showed that (1) the classification accuracy of six cities was good, the overall accuracy was above 90%, and the Kappa coefficient was above 0.88. (2) Cropland or forested areas were the most common non-wetland land coverage type in wetland cities and accounted for more than 20% or 40% of the land coverages, while water was the most common wetland type and accounted for more than 2% of the land coverages. From 2015 to 2020, the built area in most cities increased, while cropland and forest decreased significantly. (3) The wetland rate was 6.68–37.56% and the wetland protection rate was 49.48–73.74% in the six wetland cities. From 2015 to 2020, the wetland rate of the six cities were relatively stable, and the wetland protection rate of inland cities (Yinchuan, Changde, Harbin and Changshu) increased significantly, while those of coastal cities (Haikou and Dongying) decreased, which might be related to the change in coastline. Therefore, we found that the wetlands in these cities were well protected. Land cover classification for wetland cities can provide a reference for using remote sensing techniques used to monitor internationally wetland cities while also supporting the creation of additional wetland cities. [ABSTRACT FROM AUTHOR]

Wetlands provide vital ecological services for both humans and environment, necessitating continuous, refined and up-to-date mapping of wetlands for conservation and management. In this study, we developed an automated and refined wetland mapping framework integrating training sample migration method, supervised machine learning and knowledge-driven rules using Google Earth Engine (GEE) platform and open-source geospatial tools. We applied the framework to temporally dense Sentinel-1/2 imagery to produce annual refined wetland maps of the Dongting Lake Wetland (DLW) during 2015–2021. First, the continuous change detection (CCD) algorithm was utilized to migrate stable training samples. Then, annual 10 m preliminary land cover maps with 9 classes were produced using random forest algorithm and migrated samples. Ultimately, annual 10 m refined wetland maps were generated based on preliminary land cover maps via knowledge-driven rules from geometric features and available water-related inventories, with Overall Accuracy (OA) ranging from 81.82% (2015) to 93.84% (2020) and Kappa Coefficient (KC) between 0.73 (2015) and 0.91 (2020), demonstrating satisfactory performance and substantial potential for accurate, timely and type-refined wetland mapping. Our methodological framework allows rapid and accurate monitoring of wetland dynamics and could provide valuable information and methodological support for monitoring, conservation and sustainable development of wetland ecosystem. [ABSTRACT FROM AUTHOR]

Poyang Lake and Dongting Lake are the two largest freshwater lakes in China. They play a critical ecological role in regional sustainable development, which is closely related to water occurrence (WO). This study aimed to characterize the spatiotemporal changes, ecological impacts, and influencing factors of WO in the two lakes. First, this study utilized the Google Earth Engine (GEE) platform and all available Landsat images to retrieve the time series of WO in Poyang Lake and Dongting Lake on a two-year scale from 1989 to 2020. Then, the study explored the landscape variation intensity, landscape structure, and their ecological impacts on net primary production (NPP) and total nitrogen (TN) based on the landscape transfer rate (LTR), landscape indices, and geostatistical connectivity analysis. Finally, the study investigated the natural and human factors that influence the changes in WO. The major conclusions include the following: (1) the mean WO showed a significantly decreasing trend in the two lakes from 1989 to 2020. According to the LTR, the landscape variation in Dongting Lake was more intense before 2002, while after 2002, the landscape variation in Poyang Lake was more intense. (2) The landscape structure of WO gradually fragmented and diversified, along with decreasing hydrological connectivity in the two lakes. (3) The increase in NPP in Poyang Lake and the increase in TN in Dongting Lake were closely correlated with the changes in WO. (4) The upstream runoff showed a significantly positive correlation with the mean WO in Poyang Lake and the annual precipitation showed a significantly positive correlation with the mean WO in Dongting Lake; the influences of natural factors on WO changes became weaker. This study reinforces the understanding of long-term changes in the water body in Poyang Lake and Dongting Lake. [ABSTRACT FROM AUTHOR]

Sustainable Development Goals (SDGs) target 11.a is a good vision for the coordinated development of the economy, society and environment in urban agglomerations. However, there was an extreme lack of indicators, data or case studies for SDG target 11.a, since it is a vague "process target", which is not conducive to the implementation of SDG target 11.a. It is important to propose a quantitative, convenient, and local policies relevant method to promote the realization or to test the implementation effects of SDG target 11.a. Combined with socio-economic data and land use data, this study uses the methods of comprehensive evaluation model, coupling and coordination degree, and comparative advantage degree methods to study the pattern evolution, coordination characteristics and advantageous areas of production–living–ecological (PLE) functions in the Guangxi Beibu Gulf Urban Agglomeration (GBG_UA) from 1995 to 2019. The results showed that, (1) considering the spatiotemporal distribution of PLE functions, the study area has a relatively stable ecological function as well as fluctuating production and living functions. Considering the coordination characteristics of PLE functions, high–high and low–low clustering effects were observed, and primary coordination maintained the highest proportion, accounting from 55.26% in 1995 to 71.05% in 2019, indicating the SDG target 11.a level in the GBG_UA was poor. Considering the advantageous areas for PLE functions, the region mostly comprises single-function advantageous areas and a few multifunction advantageous areas, including 20 single-function advantage counties (accounting for 52%), 15 dual-function advantage counties (accounting for 39%), and three multi-function advantage counties (accounting for 7.8%), which indicates the lack of diversified land use structures in this region. (2) Optimization suggestions for the coordinated development and realization of SDG target 11.a for the GBG_UA were provided. Suggestions were made based on the radiation and driving role of Nanning city to guide the coordinated development of surrounding counties (districts). Suggestions were also made to improve the design of the integrated transportation network as well as to optimize allocation according to the resource endowment of land and to realize an upgraded ecology as well as agricultural products and services. (3) The evaluation of PLE functions is a quantitative and convenient method that can optimize national and regional development planning and test the implementation effects of SDG target 11.a. This study offers foundational knowledge for the realization of SDG target 11.a in the GBG_UA and provides a reference for the research and implementation of SDG target 11.a in other regions around the world. [ABSTRACT FROM AUTHOR]

Determining the effect of casting geometric structure on freckle formation is important in designing the directional solidification parameter of single‐crystal superalloy castings. In this research, single‐crystal castings of a third‐generation nickel (Ni)‐based superalloy with different thicknesses and structures are prepared by conventional Bridgman high‐rate‐solidification technique at withdrawal rates of 1, 3, and 6 mm min–1. The experimental results show that the freckles in castings with expansion structures are severer than those with contraction structures at a withdrawal rate of 1 mm min–1, and vice versa at withdrawal rates of 3 and 6 mm min–1. It is found that the larger casting thickness tends to promote the freckle formation at the same withdrawal rate. Furthermore, a lower tendency is displayed at the withdrawal rate of 3 mm min–1 in freckle formation, whereas an increased tendency is displayed at the withdrawal rate of 6 mm min–1. The different withdrawal rates, thicknesses, and structures of casting cause differences in cooling rate, shrinkage flow, and mushy zone morphology, which are believed to be responsible for the tendency of freckle formation. [ABSTRACT FROM AUTHOR]

In 2015, the Sustainable Development Goals (SDG) replaced the Millennium Development Goals (MDG), providing guidance and direction for the future development of countries around the world. Both MDG and SDG have established multiple indicators to achieve environmental sustainability. However, few studies have compared the changes in the ecological environment during the two periods. Therefore, this study selected the seven major river basins in China as the study area and comprehensively assessed the changes in ecosystem service importance (ESI) within different basins in the MDG and SDG periods based on six ecosystem services, including habitat quality, soil conservation, water yield, carbon storage, grain production, and aesthetic landscape. Specifically, the changes from 2000 to 2015 and 2015 to 2020 were used to represent MDG and SDG periods, respectively. The results showed that the overall ESI of the seven major river basins showed an increasing trend in both periods, and the proportion of extremely important basins reached 20.39% in 2020, mostly distributed in the Yangtze River basin and the Pearl River basin. Except for carbon storage, other ecosystem services were restored in the SDG period. However, COVID-19 and a series of sudden disasters in 2020 have greatly affected grain production and the aesthetic landscape. The fluctuation of habitat quality also indicated that although the ecological environment has a trend of recovery, there was still some degradation compared to 20 years ago. National protection policies and restoration projects have gradually improved the ecological environment of the seven river basins and are striving to reach the SDG standards step by step. However, many problems still need to be solved urgently, such as the reduction of ecological land, the increase in carbon emissions, and the weak resilience to disasters. China has made significant positive progress in MDG, and more efforts are needed to achieve the SDG goals in the future. [Display omitted] • The changes in ecosystem services and their importance of the seven major river basins in China were explored. • The ecosystem service importance has steadily increased in the MDG and SDG periods. • China ecological policies and restoration projects have been essential to mitigate the environment degradation. [ABSTRACT FROM AUTHOR]

The freckle formation and evolution in directionally solidified single-crystal specimens with different thicknesses and abruptly expanding rectangular cross-section were investigated at different withdrawal rates. The microstructure was studied by optical microscope (OP) and scanning electron microscope (SEM), and the crystallographic orientation in freckle areas was characterized by electron backscattered diffraction (EBSD). The experimental results showed that the freckle was the most severe in specimens with a thickness of 10 mm at the same withdrawal rate, and the freckle chain was observed to form below an abruptly expanding cross-section ended at the expanding step. It was found that freckles formed exclusively on the edges of casting facing the central sprue of the shell mould. Findings reveal that freckles tend to form at the highest position of the mushy zone, mainly due to the thermosolutal convection and the radial flow caused by feeding behavior in the mushy zone. The freckle formation is pronounced at a low withdrawal rate, and can further generate stray grains. • Freckle formation is more pronounced at a low withdrawal rate of 1 mm/min. • Freckles form exclusively on the edges facing the central sprue of the shell mould. • Radial flow and feeding behavior play a major role in freckle position. • Freckle grains can evolve into stray grains at a low withdrawal rate of 1 mm/min. [ABSTRACT FROM AUTHOR]

In this study, the effect of the thickness of a silica-based ceramic core on its creep deformation, either in air or under vacuum, was studied. Specimens with different thicknesses after sintering were heated to 1550 °C and by maintaining the same temperature for 40, 70 or 100 min. Scanning electronic microscopy (SEM) was employed to observe the surface microstructures and fracture morphologies of the samples. X-ray diffraction (XRD) was used to characterize the phases that formed after creep deformation. The 3D distribution of micropores and the porosities of the specimens at different states were tested by X-ray computerized tomography (XCT). The experimental results show that the effect of the thickness of the specimen on the creep deformation was notably different under different atmospheres. The creep deformation of samples with the same thicknesses under vacuum atmosphere was clearly higher than the deformation in air. In air, the creep resistance was slightly affected by the thickness of the specimen. However, the creep deformation was significantly affected by the thickness of the specimen under vacuum. The creep resistance of the 4-mm-thick specimen is noticeably higher than that of the 0.5-mm-thick specimens. The creep rate of the 0.5-mm-thick specimen is linear with the porosity of the surface layer and higher compared to the 4-mm-thick specimen, which exhibited non-linear behaviour. Reactive micropores were formed on the surface layer of these specimens under vacuum. The volume fraction of the micropores increased with increasing creep time, which resulted in the different characterization of creep for specimens with different thicknesses under vacuum. [ABSTRACT FROM AUTHOR]

Terrestrial water, an important indicator of inland hydrological status, is sensitive to land use cover change, natural disaster and climate change. An accurate and robust water extraction method can determine the surface water distribution. In this paper, a new method, called the spectrum matching based on discrete particle swarm optimization (SMDPSO) is proposed to recognize water and nonwater in Landsat 8 Operational Land Imager (OLI) images. Only two parameters, the standard water spectrum and the tile size, are considered. These parameters are sufficiently stable so it is unnecessary to change their values for different conditions. By contrast, in supervised methods, samples are chosen based on conditions. Eight test sites covering various water types in different climate conditions are used to assess the performance relative to that of unsupervised and supervised methods in terms of overall accuracy (OA), kappa coefficients (KC), commission error (CE) and omission error (OE). The results show that: (1) SMDPSO achieves the highest accuracy and robustness; (2) SMDPSO has lower OE but higher CE than the supervised method, which means that SMDPSO is the least likely to misclassify water as nonwater, but is more likely to misclassify nonwater as water; (3) SMDPSO has advantages with respect to removing shallows and dark vegetation and preserving the real distribution of small ponds, but cannot recognize shadows, ice, or clouds without the help of other data such as DEM. In addition, a case of flooding in northeastern China is analyzed to demonstrate the applicability of SMDPSO in water inundation mapping. The findings of this study demonstrate a novel robust, low-cost water extraction method that satisfies the requirements of terrestrial water inundation mapping and management. [ABSTRACT FROM AUTHOR]

Depletion of water resources has threatened water security in the Beijing-Tianjin-Hebei urban agglomeration, China. However, the relative importance of precipitation and urbanization to water storage change has not been sufficiently studied. In this study, both terrestrial water storage (TWS) and groundwater storage (GWS) change in Jing-Jin-Ji from 1979 to the 2010s were investigated, based on the global land data assimilation system (GLDAS) and the EartH2Observe (E2O) outputs, and we used a night light index as an index of urbanization. The results showed that TWS anomaly varied in three stages: significant increase from 1981 to 1996, rapid decrease from 1996 to 2002 and increase from 2002 to the 2010s. Simultaneously, GWS has decreased with about 41.5 cm (500% of GWS in 1979). Both urbanization and precipitation change influenced urban water resource variability. Urbanization was a relatively important factor to the depletion of TWS (explains 83%) and GWS (explains 94%) since the 1980s and the precipitation deficit explains 72% and 64% of TWS and GWS variabilities. It indicates that urbanization coupled with precipitation deficit has been a more important factor that impacted depletion of both TWS and GWS than climate change only, in the Jing-Jin-Ji region. Moreover, we suggested that the cumulative effect should be considered when discussing the relationship between influence factors and water storage change. [ABSTRACT FROM AUTHOR]

The microstructure of single crystal superalloy with and without tin layer on the surface of as-cast and heat-treatment state was investigated by optical microscope (OM) and scanning electron microscopy (SEM). The composition of different regions on the surface was tested by energy dispersive X-ray (EDS). The reaction intermetallic compound (IMC) formed in the heat treatment process was confirmed by X-ray diffraction (XRD). The orientations of different microstructure in samples as heat treatment state were determined by electron back-scattering diffraction (EBSD) method. The porosity location in the interdendritic region was observed by X-ray computed tomography (XCT). The experiment results showed that the remained Sn on the surface of the superalloy reacted with Ni, and then formed Ni 3 Sn 4 in the as-cast state. Sn enriched by diffusion along the porosity located in the interdendritic region and γ + γ′ (contain a little of Sn) eutectic and Ni 3 Sn 2 formed in single crystal superalloy during heat treatment, and the recalescence behaviors were found. Ni 3 Sn 2 nucleated independently in the cooled liquid at the front of (γ + γ′) (Sn) eutectic. The nucleation and growth mechanism of the eutectic and Ni 3 Sn 2 IMC during heat treatment was discussed in the present paper. [ABSTRACT FROM AUTHOR]

Wetlands play an important role in regional development and environmental protection. Under the impact of natural and artificial factors, the plateau wetlands have degenerated and even disappeared, resulting in serious problems for society and the ecological environment. It is necessary to establish a reasonable risk assessment method to evaluate the risk of wetland degradation, and then to analyze changes in the range and features of risk. For this work, the Zogie Plateau wetland was selected as the study area. For this site, a wetland degradation risk assessment method was established based on the conceptual model of Ecological Risk Assessment (ERA). The method included nine indicators used to analyze the wetland hazard index, wetland vulnerability index, and wetland degradation risk synthetically. From the spatial-temporal pattern, the wetland degradation risk was analyzed using data from 2000 to 2014. The calculated results revealed the following: (1) from 2000 to 2014, the wetland hazard index (WHI) showed a trend of increase, the value of which increased from 0.29 to 0.42, with a growth rate of 44.83%. Similarly, the wetland vulnerability index (WVI) significantly increased from 0.30 to 0.54, with a growth rate of 80%. Over the same time, the total wetland area decreased from 3910.25 km 2 to 2777.38 km 2 , a reduction of 28.97%. (2) Using the equidistant method, the risk value was divided into three risk grades. The wetland degradation risk in the whole region is increasing, and the risk rank has changed from the low risk zone (0.092) to the medium risk zone (0.25). The degradation risk becomes greater with distance from the center to fringe areas. [ABSTRACT FROM AUTHOR]

• Integrating phenology and geometry features boosts wetland classification accuracy. • Developing a novel algorithm for detailed wetland types classification. • Mapping 5 inland wetlands, 6 coastal wetlands, and 3 human-made wetlands. • First wetland map at 10-m resolution covering northern, central and southern Asia. Wetlands have suffered from considerable degradation due to anthropogenic and natural disturbances in recent decades. Although some advancements have been made, effective methods that can produce large-scale wetland maps with detailed categories are still lacking due to the diversity and complexity of wetland ecosystems. To address this issue, we developed a novel algorithm for detailed wetland types classification integrating k-fold random forest and hierarchical decision tree, and so named two-step classification algorithm. Firstly, the phenology-based features were composited based on time series Sentinel-1/2 images, and the k-fold random forest was used to extract five rough wetland types in Google Earth Engine platform. Secondly, the hierarchical decision tree designed based on geometric features was used to separate the rough wetland types into fourteen detailed types. Application of the two-step classification method in Northern, Central and Southern Asia (NCSA) resulted in a continental-scale wetland map with an overall accuracy of 90.0 ± 0.5%. Wetland types, including inland marsh, lake, river, coastal swamp, estuarine water, lagoon, shallow marine water, reservoir, canal/channel and agricultural pond, had good accuracy with both UA and PA over 77%. The remaining wetland types had moderate accuracy, with both UA and PA over 58%. As we calculated, total wetland areas of NCSA were 1,375,489.27 km2. Among the fourteen wetland categories, the inland marsh had the largest area (544,584.38 km2) and was primarily distributed in subarctic and humid continental climates, while the canal/channel had the smallest area (1,651.57 km2) and was primarily scattered in desert, semiarid and humid subtropical climates. The lake and floodplain shared generally large areas with value of 392,413.55 km2 and 173,255.71 km2 respectively, which were typically distributed across desert and semiarid climates. This study successfully mapped continental-scale wetlands with detailed categories at a 10-m spatial resolution, which can provide valuable information for the management of wetland ecosystems and facilitate the implementation of wetland-related sustainable development goals. [ABSTRACT FROM AUTHOR]

The increasing frequency of global drought events poses a significant threat to the stability of grassland ecosystems' functionality. The Inner Mongolian grasslands stand out as one of the world's most drought-prone regions, facing elevated drought risks compared to other biomes. An in-depth comprehension of the impact of drought on grassland ecosystems is paramount for their long-term sustainability. Using the Standardized Precipitation Evapotranspiration Index (SPEI) from 1982 to 2018, this study identified various drought events within the Inner Mongolian grasslands, encompassing moderate drought, severe drought, and extreme drought. The resistance of the vegetation to the different drought conditions, assessed through net primary productivity (NPP) as a metric (reflecting its capacity to maintain its original level during drought periods), was examined. The research findings indicated that the period from 2001 to 2018 witnessed a substantial increase in both the frequency and the extent of drought events compared to the period from 1982 to 2000, particularly concerning severe and extreme droughts. The areas most severely impacted by extreme drought were the Xilingol League and the Alxa League. From 1982–2000 to 2001–2018, under moderate drought conditions, vegetation resistance exhibited a minor decrease in the central and eastern regions but experienced a slight increase in the western region. In contrast, under severe drought conditions, the western region saw a significant decrease in vegetation resistance. Remarkably, under extreme drought conditions, the western region showed a substantial increase in vegetation resistance, while the central and eastern regions experienced a slight decrease. Across all three drought conditions, as precipitation levels declined, the resistance of the meadow–steppe–desert ecosystems demonstrated a high–low–high distribution pattern. The temperate desert steppe exhibited a minimal vulnerability to drought, boasting resistance levels exceeding 0.9. Notably, extreme drought had the most pronounced impact on the temperate meadow steppe, temperate steppe, and temperate desert steppe, particularly within the temperate meadow steppe category. Given these findings, the authorities responsible for grassland management should prioritize regions characterized by frequent drought occurrences and low drought resistance, such as Ulanqab City, the Xilingol League, and the western part of Hulun Buir City. Safeguarding steppe ecosystems is of paramount importance for stabilizing vegetation productivity and land carbon sinks, especially under the anticipated exacerbation of climate conditions in the future. [ABSTRACT FROM AUTHOR]

Carbon storage plays an important role in urban ecosystems. However, urban expansion leads to urban ecosystem changes and hence directly threatens carbon storage. Therefore, modelling the potential impacts of urban expansion on carbon storage is necessary. This study links the Conversion of Land Use and its Effects at Small regional extent (CLUE-S) model and the Integrated Valuation of Environmental Services and Tradeoffs (InVEST) model to analyze the potential impacts of urban expansion on carbon storage in Changsha-Zhuzhou-Xiangtan urban agglomeration from 2014 to 2023 under three urban expansion scenarios, namely Natural Increase Scenario (NIS), Cultivated Protection Scenario (CPS), and Ecological Protection Scenario (EPS). The results indicated (1) carbon storage of Changsha-Zhuzhou-Xiangtan urban agglomeration experienced a loss of 8.64 Tg from 1995 to 2009; (2) from 2014 to 2023, the carbon storage will experience the most loss of 8.54 Tg under the NIS, will experience the least loss of 7.12 Tg under the EPS, and will experience moderate loss of 7.92 Tg under the CPS; (3) the conversions of green land ecosystem and cultivated ecosystem to built-up ecosystem are the main cause of regional carbon storage loss in Changsha-Zhuzhou-Xiangtan urban agglomeration; (4) the carbon storage loss will primarily occur in the junction region of Changsha-Zhuzhou-Xiangtan urban agglomeration because every city is incline to expand toward other cities in an urban agglomeration system. We argue in favor of integrating multiple ecosystem services into urban land use planning to obtain a sustainable development. [ABSTRACT FROM AUTHOR]

China, the largest coal consumer in the world, is one of the countries that experience the most coal fires. Hence, it is critical for China to monitor coal fires and carry out coal fire monitoring, assessment, and appropriate suppression work. The Wuda coalfield, located in China's Inner Mongolia Autonomous Region, was selected as the study area. This paper was aiming to analyze spatiotemporal changes of coal fires located in Wuda of China from 2000 to 2015 and focused on the assessment of fire protection project during 2006–2008. Landsat Thematic Mapper and Enhanced Thematic Mapper Plus images were used to detect changes in coal fires over the last 16 years by utilizing a generalized single-channel method to retrieve land surface temperature data and natural breaks extracting coal fire zones. The results showed that: 1) the changes of coal fires area represented obvious three stages: Stage I (2000–2006) was before the fire suppression project with fire spread and expansion; Stage II (2006–2008) was the implementation of this project with rapid reduction of fire area; Stage III (2008–2015) was after this project with stable fire area at a low level; 2) the fire suppression work was highly successful; the area of coal fires basically remained at 192.98 ha, a reduction by 45.74% from 2000 and 62.40% from 2006 (before fire suppression projects); 3) fire suppression work in the south (zone F) and in the northwest (zone A) was the most successful, while some new patches sporadically appeared in other regions (zone B, C and D); 4) coal fire suppression methods have led to significant destruction of local geomorphology; 5) it was difficult to completely extinct coal fires underground with current suppression method. Compared with previous studies, this research paid more attention to the estimation of fire suppression projections which provided an available way for environment decision makers and coal energy producers to qualitatively assess the status and effectiveness of coal fire suppression projects. [ABSTRACT FROM AUTHOR]

Changsha–Zhuzhou–Xiangtan is an urban agglomeration along the middle reaches of the Yangtze River, the development plan of which is listed as one of national strategic development. The eco-environmental quality of the Changsha–Zhuzhou–Xiangtan urban agglomeration concerns the ecological security of China. It is essential to discuss the method of creating urban agglomeration plans to increase ecological security. In this paper, the ecosystem distributions were mapped using the CLUE-S model incorporated with Gray Model (GM) (1, 1) and an auto-logistic regression model under the conditions of a natural increase scenario (NIS), a cultivated protection scenario (CPS) and an ecological protection scenario (EPS). We analyzed the change and conversion characteristics of ecosystems both in the study area and the junction of Changsha, Zhuzhou and Xiangtan. The results showed that the ecosystem change model developed in this paper performed well in mapping future urban ecosystem distributions. The change of the ecosystem spatial distributions showed us that the built-up ecosystem would expand in the future by transforming cultivated and green land ecosystems and that the boundaries between cities would be blurred. In the whole study area, the amount of converted area from cultivated and green land to built-up land was lower in CPS and EPS than in NIS. However, in the key area, the converted result was contrary to the whole study area. Although the CPS and EPS were beneficial to the eco-environmental protection of the whole study region, the sub-regional eco-environment should be given more attention to assure that the ecological security of the whole region remains safe. [ABSTRACT FROM AUTHOR]

To understand the variation and patterns of vegetation coverage in the Yellow River Basin, as well as to promote regional ecological protection and maintain ecological construction achievements, MOD13Q1 data at a resolution of 250 m were used to calculate the annual average normalised difference vegetation index (NDVI) in a time series from 2000 to 2010. Using a variation coefficient, a Theil–Sen Median trend analysis, the Mann–Kendall test, and the Hurst index method, this study investigated the temporal and spatial variations of vegetation coverage characteristics of the Yellow River Basin. The results showed that (1) the vegetation coverage of the Yellow River appeared to have an overall trend of high in the southeast and west and low in the northwest; (2) the averaged NDVI of the whole basin fluctuated in a range of 0.3 to 0.4 from 2000 to 2010 (from 2000 to 2004 there were larger variations and these have been growing rapidly since 2005); (3) the NDVI was stable, 73.4% of the vegetation-coverage area fluctuated with a low-to-medium amplitude, while 27.6% of the area varied by a large amplitude; (4) the regions with improved vegetation coverage (62.9%) were far greater than the degraded regions (27.7%), while the sustained invariant area accounted for 9.4% of the total vegetation coverage regions; and (5) 86% of the vegetation-covered area was positively sustainable. The areas with sustainable improvement accounted for 53.7% of the total vegetation coverage area; the invariant area accounted for 7.8%. The area with sustainable degradation was 24.5%; the future variation in trends of the residual (14%) could not be determined. Therefore, continuous attention must be given to the variation in trends of vegetation in the sustainably degraded and underdetermined regions. [ABSTRACT FROM AUTHOR]

• The misorientation between two corners of triangular GCs was increased as the increase of flare angle and withdrawal rate. • The freckle chains formed at the inside corner of triangular GCs with a low flare angle under a low withdrawal rate. • The freckle defect formed at the start position of thick triangular GCs with high flare angle under a low withdrawal rate. • Under 3 mm/min withdrawal rate, 2 mm triangular GCs with 46–68° flare angle were expected to prepare high quality casting. The evolution of the crystallographic orientation and the microstructures in triangular adapters of grain continuators (GCs) with different flare angles and thicknesses prepared by a 3rd-generation single crystal (SX) superalloy were investigated under different withdrawal rates. The microstructures were observed by an optical microscope and the crystallographic orientation of the GCs was measured by electron backscatter diffraction (EBSD). The directional solidification process was simulated by a commercial simulation software ProCAST. The experimental results showed that the [001] misorientation between both sides of the GCs at top cross section increased with the increasing of the flare angle, the thickness of specimens, and the withdrawal rate. These phenomena were attributed to the changing of the isotherm morphology in the mushy zones and the velocity of the solidification front. As for a low flare angle, the freckle defect formed at one side of specimens under the withdrawal rate of 1 mm/min. With the increasing of flare angle, the freckle defect cannot be found at the same position of the specimens. The formation mechanisms of freckle defect in the triangular adapters of GCs were further discussed. [ABSTRACT FROM AUTHOR]

As one of the most open and dynamic regions in China, the Guangdong-Hong Kong-Macao Greater Bay Area (GBA) has been urbanizing rapidly in recent decades. The surface water in the GBA also has been suffering from urbanization and intensified human activities. The study aimed to characterize the spatiotemporal patterns and assess the losses and gains of surface water caused by urbanization in the GBA via long time-series remote sensing data, which could support the progress towards sustainable development goals (SDGs) set by the United Nations, especially for measuring SDG 6.6.1 indicator. Firstly, utilizing 4750 continuous Landsat TM/ETM+/OLI images during 1986–2020 and the Google Earth Engine cloud platform, the multiple index water detection rule (MIWDR) was performed to extract surface water extent in the GBA. Secondly, we achieved surface water dynamic type classification based on annual water inundation frequency time-series in the GBA. Finally, the spatial distribution and temporal variation of urbanization-induced water losses and gains were analyzed through a land cover transfer matrix. Results showed that (1) the average minimal and maximal surface water extents of the GBA during 1986–2020 were 2017.62 km2 and 6129.55 km2, respectively. The maximal surface water extent fell rapidly from 7897.96 km2 in 2001 to 5087.46 km2 in 2020, with a loss speed of 155.41 km2 per year (R2 = 0.86). (2) The surface water areas of permanent and dynamic types were 1529.02 km2 and 2064.99 km2 during 2000–2020, accounting for 42.54% and 57.46% of all water-related areas, respectively. (3) The surface water extent occupied by impervious land surfaces showed a significant linear downward trend (R2 = 0.98, slope = 36.41 km2 per year), while the surface water restored from impervious land surfaces denoted a slight growing trend (R2 = 0.86, slope = 0.99 km2 per year). Our study monitored the long-term changes in the surface water of the GBA, which can provide valuable information for the sustainable development of the GBA urban agglomeration. In addition, the proposed framework can easily be implemented in other similar regions worldwide. [ABSTRACT FROM AUTHOR]

Abstract: The microstructure and the grain orientations of one shroud prepared by directional solidification process have been investigated using metallographic method and electronic backscatter diffraction (EBSD). The results indicate that the solidification process of the tested shroud is composed of three steps: dendritic branching, the break-up and drift of the dendrite arms and the solidification of the residual liquid. Misoriented grains were formed between the primarily solidified dendrite stems during the process of recalescence which was caused by the accumulation of the solidification latent heat. A low angle grain boundary of 6° was produced across the impinging dendrite fronts. [Copyright &y& Elsevier]

Human activity is one of the most important aerosol sources. Because the underlaying surface feature records most human activities, it is important to recognize the correlation between aerosol distribution and the underlaying surface. In this research, the dark object algorithm and a second-generation operational algorithm of Moderate-Resolution Imaging Spectroradiometer (MODIS) aerosol retrieval are used to estimate aerosol optical depth from Enhanced Thematic Mapper Plus (ETM+) images acquired by the Landsat 7 satellite system in urban regions, and the correlations between aerosol distribution and urban underlaying surface features (including landform, land cover and urbanization level) is analysed. Results show that (1) it is feasible to apply a second-generation algorithm to retrieve aerosol optical depth with ETM+ images. When a validation is performed with the ground observation meteorological range converted into aerosol optical depth with the correlation model acquired by a Moderate-Resolution Atmospheric Transmission (MODTRAN) simulation, the retrieval error is about 0.0094. For higher spatial resolution of an ETM+ image, it is better to study the aerosol distribution features in the urban regions. Additionally, (2) there are obvious variations in spatial distribution of aerosol over the different features of the underlaying surface. For the landform, aerosol optical depth is mountain < hill < plain; for the land cover, aerosol optical depth is dense vegetation < sparse vegetation < water < bare soil < residential area; for the different urbanization-level regions, there is bigger and bigger aerosol optical depth with increasing of the urbanization level. On the whole, as human activities increase, so too does the aerosol optical depth. [ABSTRACT FROM AUTHOR]

Coal fire burning around the world is an environmental catastrophe characterized by the emission of noxious gases, particulate matter, and condensation by-products. In this study, coal fire temperature is retrieved based on Landsat 5 TM images and Generalized Single-Channel Algorithm (GSCA), in Wuda coalfield, Inner Mongolia, China. Then coal fire zones are extracted by Jenks' natural breaks and threshold methods based on temperature images. Changes of coal fire zones are analyzed from 1989 to 2008. The results are summarized as follows: 1) The coal fire temperature retrieval method based on Landsat 5 TM and the GSCA model is effective and feasible, because the temperature error is relatively small (from −2.9°C to +2.6°C) between the measured temperature and the retrieved temperature. 2) The accuracy is relatively high to extract coal fire zones through the Jenks' natural breaks and threshold methods, because 83.56% of surveyed area is located in the coal fire zones extracted in 2005. 3) The coal fire area increased 9.81 × 10 m from 1989 to 2005, and the annual growth is about 6.1 × 10 m, with an annual increasing rate of 2.48%. The area of coal fire decreased by 8.1 × 10 m from 2005 to 2008. [ABSTRACT FROM AUTHOR]

Abstract: Floods often take place around rivers and plains, which indicates a higher risk of flooding in these areas. This paper adopts fuzzy comprehensive assessment (FCA), simple fuzzy classification (SFC), and the fuzzy similarity method (FSM) to assess flood disaster risk in Kelantan, Malaysia. Validation data, such as the flooded area, paddy area, urban area, residential area, and refuges, were overlaid to validate and analyze the accuracy of flood disaster risk. The results show that (1) 70–75% of flooded areas lie within the higher and highest risk zones, which shows an effective assessment accuracy; (2) paddy, built-up, and residential areas concentrated in the higher and highest risk zones are more likely to be destroyed by flood disasters; (3) 200–225 refuges in the higher and highest risk zones account for around 50% of all refuges, which means that more refuges should be built in the higher and highest risk zones to meet the accommodation requirement; (4) three methods proved to be feasible and effective in evaluating flood disaster risk, among which FCA is more suitable for the study area than the two other methods. [Copyright &y& Elsevier]

Viable aneuploid embryos of pearl oyster, Pinctada martensii Dunker, were produced by inhibiting the first polar body (PB1) with cytochalasin B treatment in eggs from triploids fertilized with haploid sperm. During the period of growth measurement, aneuploid showed the slowest growth compared with diploid and triploid groups. The body size and weight measurement data showed that there were no differences between aneuploids (as a group) and diploids in body size and weight (P>0.10), but that they were significantly different from triploids (P<0.01). There were no differences between aneuploids within diploid condition (2n±n) and diploids in SL (P>0.1), but significant differences in BW were found (P<0.05). Aneuploids within triploid condition (3n±n) were significantly smaller than triploids in BW (P<0.05), but not different from triploids in SL (P>0.05), and almost identical to diploids in both (P>0.1). These dada indicated that some aneuploids might be associated with growth retardation. Karyotype analysis revealed that there were metacentric, submetacentric or subtelocentric chromosomes losses or gains; aneuploid pearl oysters with the same chromosome numbers had different chromosome composition. Aneuploids are valuable research materials for genetic analysis. [Copyright &y& Elsevier]

Terrestrial ecosystem services can offer various kinds of benefits for human life and production and play a critical role in the attainment of the Sustainable Development Goals (SDGs). The quantitative evaluation and spatial mapping of ecosystem services can offer useful information and knowledge for the natural resource protection and implementation of the SDGs. In our study, we investigated the ecosystem service value (ESV) from 2015 to 2035 under three alternative scenarios and examined their contributions to the SDGs in the Wuhan urban agglomeration. The spatial allocation algorithm, which integrates random forest regression and the CLUE-S model, was used to project the spatial distribution of land use from 2015 to 2035 under the natural increase scenario (NIS), economic development scenario (EDS), and ecological protection scenario (EPS). These simulation results generated the indicators of SDG 15.1.1 and 15.3.1. Then, the equivalent coefficients table method was leveraged to evaluate the ESV changes that resulted from land use changes, which could directly contribute to the SDG 15.9 target. The results indicated that the EDS had the lowest value for SDG 15.1.1 and the highest value for SDG 15.3.1, while the EPS had the highest value for SDG 15.1.1 and a moderate value for SDG 15.3.1. The total ESV increased from 2015 to 2035 under NIS and EPS, with gains of 5.46 and 8.86 billion CNY, respectively. In contrast, the total ESV decreased under EDS, with a loss of 0.33 billion CNY. In addition, it was found that the land degradation corresponding to SDG 15.3.1 would result in ESV losses of 8.40, 12.24, and 4.88 billion CNY under NIS, EDS, and EPS, respectively. This research developed an integrated framework to assess the potential impacts of land use changes on the ESV under three future scenarios and could offer foundational knowledge for urban development and realization of the SDGs. • Predict future patterns of land use by coupling random forest and CLUE-S model. • Evaluate ecosystem service value (ESV) using equivalent coefficients table method. • Calculate SDG 15.1.1 and 15.3.1, and link the ESV with other SDGs targets. • Analyze implications for SDGs reporting and urban sustainable development. [ABSTRACT FROM AUTHOR]

In this paper, we propose a theoretical model based on quantitative dispersion value to evaluate the influence of loss and transmission coefficient on the flatness of the interleaver. We use dispersion range (the difference between the maximum and the minimum) as the measure of flatness, and when the dispersion range is 0.352, the flatness of the interleaver is the highest. We can control the dispersion range around 0.352 by selecting appropriate parameters, achieving self-dispersion compensation. In addition, we can also utilize dispersion range as the index to guide the parameter optimization in the design stage. This method can quickly determine the optimum parameters without a large amount simulation and calculation attempts, thus saving a lot of time and cost. Not limited to the interleaver employing add–drop​ resonator Mach–Zehnder interferometer (ADR–MZI) demonstrated in this paper, our method can also apply for the parameter optimization in the fabrication of interleavers based on various infinite-impulse-response (IIR) filters. Our quantitative dispersion model can greatly reduce the cost of interleaver's parameter design process and has practical application. • Use quantitative dispersion to evaluate the flatness of the interleaver. • Realize self-dispersion compensation without introducing compensators. • Guide the parameter optimization of interleavers with the best performance. • Can be generalized to all the infinite-impulse-response filters. [ABSTRACT FROM AUTHOR]

• Wetland ecological risk is related to external hazard and internal vulnerability. • An index system consisting of 22 indexes was founded from hazard and vulnerability. • The changes of wetland ecological risk in 181 counties were quantitatively evaluated. • Protection policies have played a substantial role in wetland restoration. Wetlands are some of the most highly productive ecosystems on earth and are one of the most important environments for human survival and development. However, with the acceleration of industrialization and urbanization, wetlands have been constantly occupied and destroyed and have even disappeared in some areas, so it is necessary to establish a reasonable and scientific ecological risk assessment system for wetlands. In this study, 181 counties in Beijing-Tianjin-Hebei urban agglomeration (Jing-Jin-Ji) were selected as the research objects, and an index system with 22 indexes was established from two aspects: the external hazard degree and the vulnerability of the wetland itself. The ecological risk of the wetlands during 6 periods from 1990 to 2015 was comprehensively evaluated by long-term data and multiple index factors. The results showed that (1) due to the decrease in the hazard degree and the increase in the vulnerability, the ecological risk of the wetlands in Jing-Jin-Ji first increased and then decreased; (2) more than 60% of the counties were at the middle or middle-high risk level, especially in the center of urban development, which generally had higher risk level than other regions; (3) most wetland parks were at the middle-high risk level, while wetland reserves, reservoirs and lakes were mostly in the low risk or middle-low risk level. Therefore, in recent years, the implementation of wetland protections and restoration policies and projects has played a significant role in reducing the ecological risk of the wetlands. In the future, more targeted management and protection measures need to be formulated and followed up in time. [ABSTRACT FROM AUTHOR]

• A method for wetland simulation was proposed by coupling random forest and CLUE-S. • Three scenarios were designed to explore different modes for urban development. • The wetland patterns in WUA were predicted from 2015 to 2040 under three scenarios. • Future wetland losses/gains were examined by transition matrix and overlay analysis. Wetlands are one of the most productive ecosystems and play an important role in supporting a wide range of biodiversity and providing various kinds of ecosystem services. Rapid urbanization and climate change, however, have resulted in the disappearance of large amounts of wetlands. In this research, we developed a spatial allocation model by coupling random forest regression and the CLUE-S algorithm to simulate the spatial dynamics of wetlands in the Wuhan Urban Agglomeration. Then, the calibrated model was used to predict the wetland distributions from 2015 to 2040 under three scenarios, i.e. natural increase scenario (NIS), economic development scenario (EDS), and wetland protection scenario (WPS). The results showed that: (1) the natural wetlands exhibit a slight decreased trend under EDS, and a slight increased trend under WPS. But regardless of scenarios, the natural wetlands will suffer from degradation in densely built-up areas during 2015–2040; (2) The ponds will clearly expand under all scenarios, and most of their expansion distribute in Xiantao city; (3) The paddy will continue to degradation under three scenarios, and the area decreases most under EDS with value of 2866.94 km2. Most of the paddy degradation are located in Wuhan, Xiantao and Ezhou city. The proposed framework offered an effective tool to explore the urban wetland dynamics in the future, and revealed wetland distribution under different scenarios, which could provide support for the protection of urban wetlands and sustainable future develop in the Wuhan Urban Agglomeration. [ABSTRACT FROM AUTHOR]

The eco-environment is dynamic and shows a continuous process of long-term change. It is helpful for policymakers to know the status of the regional eco-environment through accurate evaluations of the history and current situation of the regional eco-environment. The remote sensing ecological index (RSEI) model of China was established in this study by using four indexes: wetness, greenness, dryness, and heat. Knowledge granulation of the RSEIs were carried out, and a method to determine the weights of the knowledge granulation entropy of the indexes based on their characteristics was proposed. This study used Moderate Resolution Image Spectroradiometer (MODIS) data from the Google Cloud Computing Platform to study and calculate the eco-environmental quality of China from 2000–2017. The overall eco-environmental quality in China tended to improve from 2000–2017, although there were large areas of ecological degradation from 2009–2014. The eco-environment of eastern China was better than that of western China. Most of the national ecological areas were third-level ecological areas, which had moderate environmental quality. Dryness was the most important factor affecting the quality of the eco-environment, followed by greenness, which reflected the increasing environmental damage caused by human activities in China in recent years. [ABSTRACT FROM AUTHOR]

Wetlands play a critical role in the environment. With the impacts of climate change and human activities, wetlands have suffered severe droughts and the area declined. For the wetland restoration and management, it is necessary to conduct a comprehensive analysis of wetland loss. In this study, the Xiong'an New Area was selected as the study area. For this site, we built a new method to identify the patterns of wetland loss integrated the landscape variation and wetland elements loss based on seven land use maps and Landsat series images from the 1980s to 2015. The calculated results revealed the following: (1) From the 1980s to 2015, wetland area decreased by 40.94 km2, with a reduction of 13.84%. The wetland loss was divided into three sub stages: the wet stage from 1980s to 2000, the reduction stage from 2000 to 2019 and the recovering stage from 2009 to 2015. The wetland area was mainly replaced by cropland and built-up land, accounting for 98.22% in the overall loss. The maximum wetland area was 369.43 km2 in the Xiong'an New Area. (2) From 1989 to 2015, the normalized difference vegetation index (NDVI), normalized difference water index (NDWI) and soil moisture monitoring index (SMMI) showed a degradation, a slight improvement and degradation trend, respectively. The significantly degraded areas were 80.40 km2, 20.71 km2 and 80.05 km2 by the detection of the remote sensing indices, respectively. The wetland loss was mainly dominated by different elements in different periods. The water area (NDWI), soil moisture (SMMI) and vegetation (NDVI) caused the wetland loss in the three sub-periods (1980s–2000, 2000–2009 and 2009–2015). (3) According to the analysis in the landscape and elements, the wetland loss was summarized with three patterns. In the pattern 1, as water became scarce, the plants changed from aquatic to terrestrial species in sub-region G, which caused the wetland vegetation loss. In the pattern 2, due to the water area decrease in sub-regions B, C, D and E, the soil moisture decreased and then the aquatic plants grew up, which caused the wetland loss. In the pattern 3, in sub-region A, due to the reduction in water, terrestrial plants covered the region. The three patterns indicated the wetland loss process in the sub region scale. (4) The research integrated the landscape variation and element loss appears potential in the identification of the loss of wetland areas. [ABSTRACT FROM AUTHOR]

The spatiotemporal changes of open-surface water bodies in the Yangtze River Basin (YRB) have profound influences on sustainable economic development, and are also closely relevant to water scarcity in China. However, long-term changes of open-surface water bodies in the YRB have remained poorly characterized. Taking advantage of the Google Earth Engine (GEE) cloud platform, this study processed 75,593 scenes of Landsat images to investigate the long-term changes of open-surface water bodies in the YRB from 1984 to 2018. In this study, we adopted the percentile-based image composite method to collect training samples and proposed a multiple index water detection rule (MIWDR) to quickly extract the open-surface water bodies. The results indicated that (1) the MIWDR is suitable for the long-term and large-scale Landsat water bodies mapping, especially in the urban regions. (2) The areas of permanent water bodies and seasonal water bodies were 29,076.70 km2 and 21,526.24 km2, accounting for 57.46% and 42.54% of the total open-surface water bodies in the YRB, respectively. (3) The permanent water bodies in the YRB increased along with the decreases in the seasonal water bodies from 1984 to 2018. In general, the total open-surface surface water bodies in the YRB experienced an increasing trend, with an obvious spatial heterogeneity. (4) The changes of open-surface water bodies were associated with the climate changes and intense human activities in the YRB, however, the influences varied among different regions and need to be further investigated in the future. [ABSTRACT FROM AUTHOR]

• Urban water bodies in China showed a significant spatial autocorrelation in spatial distribution. • About 40% and 60% of total cities were detected with a mutation point in urban permanent and seasonal water bodies, respectively. • GDP explained about 13 %∼35 % of spatiotemporal variations of urban water bodies in China. Urban water bodies constitute a vital element within the urban ecosystem. Knowledge of the spatiotemporal changes in urban water bodies and their relationship with economic development in China is critical for sustainable development. However, previous studies usually investigated the spatiotemporal changes of urban water bodies at discrete time points and ignored the relationship between urban water bodies and economic development. Here, this study first corrected freely available water body products based on spatiotemporal majority filter, thereby obtaining an improved yearly urban water body dataset. Then, the research adopted Moran's I and Anselin Local Moran's I to explore the spatial distribution patterns of urban water bodies and employed linear regression and segmented linear regression to investigate the temporal abrupt change and long-term trend of urban water bodies. Finally, we used geodetector to evaluate the relative contributions of GDP to the spatial heterogeneity of trends in urban water bodies. The study revealed a significant spatial autocorrelation in the distribution of urban water bodies, particularly notable in the "High-High" cluster within the Yangtze and Pearl River Deltas. It was observed that approximately 40 % and 60 % of total cities experienced an abrupt change in permanent and seasonal urban water bodies, respectively. Specifically, the majority of these abrupt changes occurred during 2010–2013. When considering both long-term trends and abrupt changes, permanent urban water bodies in Chinese cities exhibited primarily a steadily increasing trend, while seasonal water bodies in Chinese cities displayed two distinct temporal patterns: a steadily increasing trend and a decreasing trend followed by a subsequent increasing trend. Furthermore, it was noted that GDP exhibited a significantly positive correlation with the temporal changes of permanent urban water bodies from 2000 to 2020 at the national scale while it first showed a significantly negative correlation with the temporal changes of seasonal urban water bodies from 2000 to 2012 and then showed a significantly positive correlation from 2012 to 2020 on a national scale. In conclusion, we found that GDP played a more important role in driving the spatial heterogeneity of trends in urban water bodies during 2012–2020 compared to 2000–2012, with the relative contribution of ∼ 32.5 %. [ABSTRACT FROM AUTHOR]

The use of remote sensing to monitor surface water bodies has gradually matured. Long-term serial water change analysis and floods monitoring are currently research hotspots of remote sensing hydrology. However, these studies are also faced with some problems, such as coarse temporal or spatial resolution of some remote sensing data. In general, flood monitoring requires high temporal resolution, and small-scale surface water extraction requires high spatial resolution. The machine learning method has been proven to be effective against long-term serial surface water extraction, such as random forests (RFs). MODIS data are well suited for large-scale surface water dynamic analysis and flood monitoring because of its short return cycle and medium spatial resolution. In this paper, the Yangtze River Basin (YRB) in China was selected as the study area, and two MODIS products (MOD09A1 and MOD13Q1) and RF method were used to extract the surface water from 2000 to 2016. Considering the disadvantages of temporal or spatial resolution of these two MODIS products, this study also presents a data fusion method to combine them and get higher spatiotemporal resolution water results. Finally, 762 surface water maps from 2000 to 2016 are obtained, whose temporal and spatial resolution is every eight days and 250 m, respectively. In addition, water extent variation is analyzed and compared to observed precipitation data. The main conclusions are as follows: (1) this constructed approach for long-term serial surface water extraction based on the RF classifier is feasible, and a good fusion method is used to obtain the surface water body with higher spatiotemporal resolution; (2) the maximum area of the surface water extent is 48.53 × 103 km2, and seasonal and permanent water areas are 20.51 × 103 km2 and 28.01 × 103 km2, respectively; (3) surface water area is increasing in the YRB, such that seasonal water area decreased by 3450 km2, and the permanent water area increased by 3565 km2 in 2001–2015; (4) precipitation is the main factor causing variation in the surface water bodies, and they both show an increasing trend in 2000–2016. As such, the approach is worth referring to other remote sensing applications, and these products are very both valuable for water resource management and flood monitoring in the study area. [ABSTRACT FROM AUTHOR]

Changes in heavy precipitation events (HPEs) are closely related to hydrological disasters, such as floods and urban water logging. This study investigated the spatiotemporal changes in HPEs by using hourly precipitation data from the warm season (from May to September) from 1980 to 2016 in the Beijing-Tianjin-Hebei (BTH) region. Sen's slope estimator and the modified Mann-Kendall test were used to detect the temporal trend. A circular statistical approach was used to analyze the diurnal distribution of HPEs. The study found that the temporal changes in the HPEs in the BTH region could be divided into three stages: 1980–1994, 1994–2002, and 2002–2016. The first period and the last period witnessed an increase in the frequency and maximum intensity of HPEs, while the second period experienced a decreasing trend in the frequency and maximum intensity of HPEs. By comparing the HPEs in the first and last periods, the study revealed that the short-duration HPEs (HPEs of 1–6 h in duration) became more frequent and more extreme, while the long-duration HPEs (HPEs lasting longer than 6 h) became less frequent and less extreme. In addition, the study found that the peak time of the short-duration HPEs occurred from 19:00 local standard time (LST) to 24:00 LST; however, the peak time of the long-duration HPEs occurred from 01:00 LST to 06:00 LST. Moreover, the peak time of short-duration HPEs tended to be more concentrated than that of long-duration HPEs. Because an increasing number of short-duration HPEs occurred in the period of 2002–2016, the peak time of the HPEs in the BTH region was delayed and more concentrated. Local temperature showed an obvious correlation with the changes in HPEs at the decadal timescale. Our study provided useful information about spatiotemporal changes in precipitation events at the sub-daily scale in the BTH region. [ABSTRACT FROM AUTHOR]

• A framework is proposed to integrate machine learning, ecological footprints and PLUS models. • Coupling of multiple data sources with machine learning algorithms improves classification accuracy. • The random forest algorithm is optimal for comparison accuracy. • Improved ecological footprint models to improve the accuracy of ECC. • Restoration of forest land with the highest ECC potential. Ecological carrying capacity is key to evaluating sustainable development capacity, and land use change has varying degrees of impact on ecosystems. This study explores the ecological carrying capacity based on land use change, which is important for the conservation and scientific and rational use of ecosystems. Therefore, in this study, three machine learning classification 3algorithms, namely support vector machine, random forest and artificial neural network, were selected for accuracy comparison and analysis based on multi-source data, using Southwest Guangxi Karst-Beibu Gulf as the study area. The Patch-generating Land Use Simulation Model is used to dissect the spatial and temporal changes in ecological carrying capaciyt from 1990 to 2040 and future trends. The results showed that (1) Coupling multiple sources of data and machine learning classification algorithms can ultimately improve land use classification accuracy. The RF is compared and found to be the optimal classification algorithm for this study. (2) The area of arable and grassland gradually decreases between 1990 and 2040, mainly encroached upon by build land; the area of forested land gradually recovers, the watershed fluctuates up and down, and the area of build land gradually increases. (3) The ecological carrying capacity from 1990 to 2040 shows a trend of decreasing and then increasing, and the area of low and medium–low decreases from 2020 to 2040, with arable land and forest land having a stronger potential to increase ecological carrying capacity. Nanning City, Qinzhou City and Chongzuo City are severely damaged. The framework provides an effective tool for exploring future ecological carrying capacity to support the ecological conservation and future sustainable development of the region. [ABSTRACT FROM AUTHOR]

To systematically investigates the forming ability and properties of micro-arc oxidation (MAO) coatings on magnesium alloys using different types of single electrolytes and further enhance the understanding of the coating formation mechanism from multiple perspectives. MAO treatments were performed in three types of single electrolyte solutions containing either sodium silicate, potassium fluoride, or sodium hydroxide, which were severally designed in terms of main salts, additives, and alkaline substances. The results show that MAO coatings could still be formed in the three single electrolyte solutions; however, the sparks and observable phenomena on the sample surface differed obviously from those in multicomponent electrolytes. In potassium fluoride and sodium hydroxide electrolytes, sparks occurred continuously at fixed positions on the sample surface, forming concave defects with uneven distributions of Mg, F, and O on the coating surface. In addition, a larger response current was observed in the sodium hydroxide electrolyte during MAO; this is disadvantageous in reducing energy consumption. The coating obtained in the potassium fluoride electrolyte had the highest thickness and number of micropores because of the synergy between the electrochemical process and the spark state on the sample surface. In contrast, the coating prepared in the sodium silicate electrolyte exhibited better corrosion resistance because of a certain thickness and good compactness. [ABSTRACT FROM AUTHOR]

• Improved ecological footprint model for assessing ECC. • Constructed an ecological safety pattern based on the "history-present-future" concept. • Constructed an integrated ecological security network of points, lines and surfaces. • Proposed an ecological security optimization scheme of "two belts, three screens, four zones and multiple centres". The construction of ecological security pattern and ecological security network and reasonable ecological security planning are of great significance for ecosystem protection and restoration and optimal regulation. This study takes the Southwest Guangxi Karst - Beibu Gulf as the study area. Based on the improved ecological footprint model and the Patch-generating Land Use Simulation (PLUS) model, the ecological carrying capacity changes and driving mechanisms from 1990 to 2040 were analysed. The study proposed the idea of "history-present-future" to construct an ecological security pattern, We have constructed an integrated "points, lines and surfaces" ecological security network and carried out ecological security optimization planning. The results show that (1) The overall 1990–2040 belongs to the medium-high carrying capacity grade, showing a trend of rising and then falling, and the spatial changes are dominated by the type of unchanging ecological carrying capacity. Nanning is the most severely damaged. Slope and temperature are the main driving factors. (2) A total of 17 ecological source patches were identified in this study. The ecological source patches account for the overall area in general, and their distribution is relatively concentrated, so the ecological security of the central city needs to be focused on. (3) This study extracts 17 ecological corridors and 11 karst ecological corridors, generating an integrated ecological security network structure of "points, lines and surfaces". The ecological optimization planning proposal of "two belts, three screens, four zones and multiple centers" is proposed. [ABSTRACT FROM AUTHOR]

Temperature and precipitation are considered to be the most important indicators affecting the green-up date. Sensitivity of the green-up date to temperature and precipitation is considered to be one of the key indicators to characterize the response of terrestrial ecosystems to climate change. We selected the main grassland types for analysis, including temperate steppe, temperate meadow steppe, upland meadow, and lowland meadow. This study investigates the variation in key meteorological indicators (daily maximum temperature (Tmax), daily minimum temperature (Tmin), and precipitation) between 2001 and 2018. We then examined the partial correlation and sensitivity of green-up date (GUD) to Tmax, Tmin, and precipitation. Our analysis indicated that the average GUD across the whole area was DOY 113. The mean GUD trend was −3.1 days/decade and the 25% region advanced significantly. Tmax and Tmin mainly showed a decreasing trend in winter (p > 0.05). In spring, Tmax mainly showed an increasing trend (p > 0.05) and Tmin a decreasing trend (p > 0.05). Precipitation showed no significant (p > 0.05) change trend and the trend range was ±10 mm/decade. For temperate steppe, the increase in Tmin in March promotes green-up (27.3%, the proportion of significant pixels), with a sensitivity of −0.17 days/°C. In addition, precipitation in April also promotes green-up (21.7%), with a sensitivity of −0.32 days/mm. The GUDs of temperate meadow steppe (73.9%), lowland meadow (65.9%), and upland meadow (22.1%) were mainly affected by Tmin in March, with sensitivities of −0.15 days/°C, −0.13 days/°C, and −0.14 days/°C, respectively. The results of this study reveal the response of vegetation to climate warming and contribute to improving the prediction of ecological changes as temperatures increase in the future. [ABSTRACT FROM AUTHOR]

• Spatiotemporal evolution and destruction degree of wetlands from 1990 to 2018. • Comparison and Selection of Four Intelligent Algorithms for Land Cover Classification. • CA-Markov, support vector machine algorithm, wetland evolution prediction in 2018–2035. Wetlands are an important transitional ecosystem, and they play an important role in maintaining ecological balance. However, human activities and climate change have led to a decrease in wetlands. Therefore, to explore the degree of damage and assess the future trends of Guangxi wetlands, this study used the Google Earth Engine (GEE) cloud platform, and the support vector machine algorithm was selected for comparison and analysis to simulate the accuracy of land cover. GIS was used to analyse the evolution and degree of damage of nearly 30 Guangxi wetlands. The geographic detector model was used to explore the driving mechanism, and finally, the CA-Markov model and multi-scenario simulation were used to predict the wetland evolution from 2018 to 2035 to reveal the future direction of development. The results showed that (1) From 1990 to 2018, paddy fields accounted for the largest proportion of wetlands in Guangxi. In the past 30 years, the total area of wetlands in Guangxi has been degraded, with a total decrease of 983.33 km2. (2) The degree of wetland damage results showed that the total damaged area was greater than the total restored area, The wetland damage in Nanning city was the most serious, with an area difference of 503.22 km2 between the damaged and restored areas. (3) The analysis of the driving mechanism of wetland damage showed that distance from cities and towns, average precipitation and population density were the main driving factors. (4) The spatial distribution of natural development and economic construction in 2035 will be slightly damaged; additionally, the spatial distribution of ecological protection will expand as a whole. From 2025 to 2035, wetlands will be basically stable under Natural Development Scenario (NDS), degraded each year under the Economic Construction Scenario (ECS), and steadily increased each year under Ecological Protection Scenario (EPS). [ABSTRACT FROM AUTHOR]

• A new Al 16 Fe 10 Cr 20 Ni 24 Co 30 (at. %) HEA has been developed. • The low ductility of the as-cast AC HEA is due to the stress localization. • The partly recrystallized R800 HEA possesses multi-scale heterogeneous two-phase lamellar structure. • B2 nanoprecipitates share the stress and promotes the formation of SFs. Two-phase high-entropy alloys (HEAs) have high strength due to the contribution of interface-dependent strengthening, but the deformation incompatibility between the two phases causes instability. The initiation of cracks occurs at the two-phase interfaces, which ultimately leads to low ductility. To overcome this problem, the strategy proposed in this work is to introduce nanoprecipitates as a buffer zone and simultaneously promote stress release caused by the formation of stacking faults (SFs) at the two-phase interfaces, reducing the stress localization at the two-phase interface, thus improving the ductility. The Al 16 Cr 20 Fe 10 Co 30 Ni 24 HEA was chosen as the model material to evaluate this approach. After rolling at 800 °C, the HEA had a two-phase lamellar structure consisting of a face-centered cubic (FCC) phase and an ordered body-centered cubic BCC (B2) phase. Recrystallization occurred within the FCC phase, and precipitates were present in both the FCC and B2 lamellae. The B2 nanoprecipitates in the FCC phase play the most important role, contributing to the improvement of yield strength and buffering the direct contact between gliding dislocations and the two-phase interface. In addition, the B2 nanoprecipitates also promote the widespread formation of SFs at the two-phase interfaces, leading to stress release. More importantly, nanoprecipitates are nucleation sites for SFs. The formation of an SF network improves the strain-hardening ability. The HEA shows a yield strength of 1,120 MPa and an ultimate tensile strength of 1,540 MPa while still exhibiting an elongation to fracture of ∼25 %. [ABSTRACT FROM AUTHOR]

A relative lag in research methods, technical means and research paradigms has restricted the rapid development of geography and urban computing. Hence, there is a certain gap between urban data and industry applications. In this paper, a spatial association discovery framework for the urban service industry based on a concept lattice is proposed. First, location data are used to form the formal context expressed by 0 and 1. Frequent closed itemsets and a concept lattice are computed on the basis of the formal context of the urban service industry. Frequent closed itemsets can filter out redundant information in frequent itemsets, uniquely determine the complete set of all frequent itemsets, and be orders of magnitude smaller than the latter. Second, spatial frequent closed itemsets and association rules discovery algorithms are designed and built based on the formal context. The inputs of the frequent closed itemsets discovery algorithms include the given formal context and frequent threshold value, while the outputs are all frequent closed itemsets and the partial order relationship between them. Newly added attributes create new concepts to guarantee the uniqueness of the new spatial association concept. The inputs of spatial association rules discovery algorithms include frequent closed itemsets and confidence threshold values, and a rule is confident when and only if its confidence degree is not less than the confidence threshold value. Third, the spatial association of the urban service industry in Nanning, China is taken as a case to verify the method. The results are basically consistent with the spatial distribution of the urban service industry in Nanning City. This study enriches the theories and methods of geography as well as urban computing, and these findings can provide guidance for location-based service planning and management of urban services. [ABSTRACT FROM AUTHOR]

Due to the widespread presence of noise, such as clouds and cloud shadows, continuous, high spatiotemporal-resolution dynamic monitoring of lake water extents is still limited using remote sensing data. This study aims to take an approach to mapping continuous time series of highly-accurate lake water extents. Four lakes from diverse regions of China were selected as cases. In order to reduce the impact of noise and ensure high spatial and temporal resolution of the final results, two sets of MODIS products (including MOD09A1 and MOD13Q1) are used to extract water bodies. This approach mainly comprises preliminary classification, post processing and data fusion. The preliminary classification used the Random Forest (RF) classifier to efficiently and automatically obtain the initial classification results. Post-processing is implemented to repair the classification results affected by noise as much as possible. The processed results of the two sets of products are fused by using the Homologous Data-Based Spatial and Temporal Adaptive Fusion Method (HDSTAFM), which reduces the effect of noise and also improve the temporal and spatial resolution for the final water results. We determined the accuracy using Landsat-based water results, and the values of overall accuracy (OA), user's accuracy (UA), producer's accuracy (PA), and kappa coefficients (KC) are mostly greater than 0.9. Good correlation was achieved for a time series of water area and altimetry data, obtained by multiple satellites, and also for water-level data selected from hydrological stations. [ABSTRACT FROM AUTHOR]

Highlights • Reviewed the principles, developments, and applications of various WIs. • Included applications in surface water, vegetation water, soil water, and wetland. • Summarized the terminology of WIs in different applications. • Designed a field experiment to examine the sensitivities of various WIs. Abstract Water status is an important indicator of ecosystem health. Based on the spectral signatures of liquid water and other land surface features (e.g., soil and vegetation), many water-related spectral reflectance indices (WIs) have been developed to characterize the presence of liquid water. These WIs are widely used in agricultural and ecological applications including surface water body characterization, vegetation water status estimation, soil water content assessment, and wetland (e.g., paddy rice) monitoring. However, choosing the correct WIs for specific studies is confusing due to arbitrary selections of WIs in respective applications and the mixing of WIs names in different studies. To increase the clarity of appropriate usage of WIs in specific conditions, this study reviewed the principles, developments, and applications of various WIs to identify the suitability of WIs for different applications. We started with the discussion of the underlying principles and developments (e.g., from ratio to normalized difference of two bands) of different WIs, based on the spectrum features of water, vegetation, and soil from widely used spectral libraries. Applications from different studies, in each category, were then compared to show the performances of different WIs. This is followed by a brief summary about the terminology of WIs in different studies to further reduce the confusion caused by the mixed use of WIs terms. A field experiment was designed to investigate the dynamics of various WIs in response to different mixing ratios of water and soil or plant. The effectiveness of combining WIs and greenness indices for detecting surface water body and wetland were evaluated using the field experiment data. Finally, we identified the major gaps and pointed out the potential improvements for the future. [ABSTRACT FROM AUTHOR]

Abstract: River flooding—the world's most significant natural hazard—is likely to increase under anthropogenic climate change. Most large rivers have been regulated by damming, but the extent to which these impoundments can mitigate extreme flooding remains uncertain. Here the catastrophic 2016 flood on the Changjiang River is first analyzed to assess the effects of both the Changjiang's reservoir cascade and the Three Gorges Dam (TGD), the world's largest hydraulic engineering project on downstream flood discharge and water levels. We show that the Changjiang's reservoir cascade impounded over 30.0 × 103 m3/s of flow at the peak of the flood on 25 July 2016, preventing the occurrence of what would otherwise have been the second largest flood ever recorded in the reach downstream of the TGD. Half of this flood water storage was retained by the TGD alone, meaning that impoundment by the TGD reduced peak water levels at the Datong hydrometric station (on 25 July) by 1.47 m, compared to pre‐TGD conditions. However, downstream morphological changes, in particular, extensive erosion of the natural floodplain, offset this reduction in water level by 0.22 m, so that the full beneficial impact of floodwater retention by the TGD was not fully realized. Our results highlight how morphological adjustments downstream of large dams may inhibit their full potential to mitigate extreme flood risk. [ABSTRACT FROM AUTHOR]