Search Results (18)

Cropland and rural settlements are core components of rural human–environment systems, and their coordinated development is crucial for regional sustainability, particularly in China’s major agricultural production regions. Taking the Huang-Huai-Hai region as the study area, this study systematically investigates the spatiotemporal evolution of cropland and its coupling relationship with rural settlements using land use data from 1990 to 2020. Grid-based analysis and multiple spatial modeling methods were employed. The results show that: (1) From 1990 to 2020, the cropland in the region decreased by a net total of 21,021.94 km², with annual dynamic degrees ranging from −0.13% to −0.28%. Cropland conversion to other land uses far exceeded conversion from others, with construction land being the primary destination. Among these, rural settlements and urban construction land accounted for 43.75% and 55.58% of the total cropland loss, respectively. (2) The spatial distribution of cropland exhibited a distinct pattern of “hot in the center and south, cold in the periphery and north” (Moran’s I = 0.232, p < 0.001), indicating significant positive spatial autocorrelation. Hot spot areas clustered in the North China Plain and the Huang-Huai Plain, while cold spot areas were distributed in the Yanshan–Taihang mountains and the hilly regions of the Shandong Peninsula, clearly controlled by topography. (3) Cropland change exhibited stage-specific characteristics. The pattern was relatively stable during 1990–2000. During 2000–2010, cropland conversion to other uses intensified, with high-value conversion areas concentrated around urban agglomerations. In the 2010–2020 period, these high-value conversion areas diffused from the core plain areas to urban fringe zones. (4) The spatial coupling between cropland and rural settlements was predominantly characterized by the Moderately Coordinated Type (MCT), accounting for 48.38–58.44% of the area. However, the proportion of Rural Settlement-Dominant Type (RC) increased from 15.51% to 21.58%, indicating a trend toward intensifying human–environment conflicts. Overall, the Huang-Huai-Hai region experienced significant cropland changes. While its spatial pattern remains relatively stable, the coupling relationship between cropland and rural settlements is deteriorating, posing challenges to regional food security and rural sustainable development. Full article

Accurate lightning data are critical for disaster warning and climate research. This study systematically compares the Fengyun-4A Lightning Mapping Imager (FY-4A LMI) satellite and the Advanced Time-of-arrival and Direction (ADTD) lightning location network in the Beijing-Tianjin-Hebei (BTH) region (April–August, 2020–2023) using coefficient of variation (CV) analysis, Welch’s independent samples t-test, Pearson correlation analysis, and inverse distance weighting (IDW) interpolation. Key results: (1) A significant systematic discrepancy exists between the two datasets, with an annual mean ratio of 0.0636 (t = −5.1758, p < 0.01); FY-4A LMI shows higher observational stability (CV = 5.46%), while ADTD excels in capturing intense lightning events (CV = 28.01%). (2) Both datasets exhibit a consistent unimodal monthly pattern peaking in July (moderately strong positive correlation, r = 0.7354, p < 0.01) but differ distinctly in diurnal distribution. (3) High-density lightning areas of both datasets concentrate south of the Yanshan Mountains and east of the Taihang Mountains, shaped by topography and water vapor transport. This study reveals the three-factor (climatic background, topographic forcing, technical characteristics) coupled regulatory mechanism of data discrepancies and highlights the complementarity of the two datasets, providing a solid scientific basis for satellite-ground data fusion and regional lightning disaster defense. Full article

Intensified water consumption has driven rapid groundwater depletion globally, threatening economic and environmental sustainability. Understanding large-scale groundwater dynamics has been constrained by the scarcity of long-term, high-resolution records. This study uses multi-decadal, high-density groundwater level monitoring data from the Southern Hebei Plain (SHP) to analyze the evolution of the groundwater flow field and depression cones from 1959 to 2020. We quantitatively characterize trends over six decades and assess the impact of the South-to-North Water Diversion Project (SNWD). The regional flow field shifted from a natural topographic-driven pattern (foothills to coast) in the 1960s to localized systems centered on depression cones by the 1980s. Subsequent management policies and the SNWD have progressively reduced the extent of these cones, facilitating a partial recovery of the regional flow pattern towards its original direction. Shallow aquifer levels declined steeply from the 1980s until 2016, particularly along the Taihang Mountains’ alluvial fan margins, with cumulative drawdown of 20–60 m. After SNWD implementation, levels stabilized and began recovering in piedmont urban areas. Deep aquifer levels generally declined from the 1980s to 2016, with the most significant drawdown (40–90 m) occurring in the central–eastern plain. The recovery of deep aquifers lagged behind shallow ones. These results provide critical insights for supporting sustainable groundwater management and depression cone recovery in the Hebei Plain. Full article

Ecological security evaluation serves as the cornerstone for ecological management decision-making and spatial optimization. This study focuses on the Dongping Lake Basin. Based on the Pressure–State–Response (PSR) model framework, it integrates ecological risk, ecosystem health, and ecosystem service indicators. Utilizing methods including Local Indicators of Spatial Association (LISA), Transition Matrix, and GeoDetector, it analyzes the spatio-temporal evolution characteristics and driving mechanisms of watershed ecological security from 2000 to 2020. The findings reveal that the Watershed Ecological Security Index (WESI) exhibited a trend of “fluctuating upward followed by periodic decline”. In 2000, the status was “relatively unsafe”. It peaked in 2015 (index 0.332, moderately safe) and experienced a slight decline by 2020. Spatially, a significantly clustered pattern of “higher in the north and lower in the south, higher in the east and lower in the west” was observed. In 2020, “High-High” clusters of ecological security aligned closely with Shandong Province’s ecological conservation red line, concentrating in core protected areas such as the foothills of the Taihang Mountains and Dongping Lake Wetland. Level transitions were characterized by “predominant continuous improvement in low levels alongside localized reverse fluctuations in middle and high levels,” with the “relatively unsafe” and “moderately safe” levels experiencing the largest transfer areas. Geographical detector analysis indicates that the Human Interference Index (HI), Ecosystem Service Value (ESV), and Annual Afforestation Area (AAA) were key drivers of watershed ecological security change, influenced by dynamic interactive effects among multiple factors. This study advances watershed-scale ecological security assessment methodologies. The revealed spatio-temporal patterns and driving mechanisms provide valuable insights for protecting the ecological barrier in the lower Yellow River and informing ecological security strategies within the Dongping Lake Watershed. Full article

Since entering the process of industrialization, human activities have interfered with the original ecological environment, and the expansion of cities has also impacted the ecological service function. In order to maintain the balance of the ecosystem and the stability of ecological security, it is very important to establish an ecological security network (ESN), particularly in transitional geospace. To address this, we proposed a framework for mountainous transitional geospace by morphological spatial pattern analysis and circuit theory. Taihang Mountain area is applied as a case, establishing a suitable evaluation system for the mountainous transitional geospace. Using circuit theory to quantitively construct the ESN, it was found that there are 34 ecological sources in the Taihang Mountain area. The corridors primarily run north–south in the east and west but display a mesh-like layout in the central and southern parts. These elements integrated an ESN of “four zones and three lines”. Key ecological pinch point areas are primarily in plains or plateaus, and ecological barrier restoration areas are mainly in basins and mountainous areas. The study provides recommendations for protection and restoration work in the Taihang Mountain area, which hold both theoretical and practical significance for ecological planning. Full article

With rapid economic development and the change in land use patterns, the region faces the environmental challenge of increasing carbon emission risk. The research on analyzing and identifying carbon emission risk of land use is helpful to realize regional sustainable development. This study takes the Yanshan-Taihang Mountain area of Hebei Province as a case study. Based on the remote sensing monitoring data of land use in 2010, 2015, and 2020, the carbon emissions of land use are calculated by direct and indirect calculation methods. Then, the carbon footprint pressure index and land use carbon emission risk index are introduced to analyze the temporal and spatial differentiation characteristics of land use carbon emission risk in the study area. The findings indicate that carbon emissions associated with land use in the study area initially exhibited an increasing trend, followed by a subsequent decline over time. In space, the high-value areas of carbon emissions are mainly distributed in the south of the study area, and the low-value areas of carbon emissions are mainly concentrated in the northeast of the study area. The region experiences significant carbon-cycling pressure and environmental risk, with the proportion of counties in carbon balance areas decreasing from 27.27% in 2010 to 18.18% in 2020, and the proportion of counties in carbon imbalance areas increasing from 72.72% in 2010 to 81.82% in 2020. The carbon emission risk of land use is divided into micro-risk area, low-risk area, medium-risk area, high-risk area, and severe-risk area. From 2010 to 2020, there was an 18.18% increase in the percentage of counties classified as high-risk and severe-risk areas. Additionally, the regions identified as hotspots for land use emissions exhibited a trend in expansion. This phenomenon indicates that these areas have not successfully managed to mitigate environmental pollution or ensure the sustainable use of resources in the context of their economic development efforts. This series of dynamic changes shows that the study area is facing the challenge of increasing carbon emission risk from land use. Governments at all levels should strengthen environmental governance in high-risk areas, implement stricter land use policies, and promote green development and cleaner production to attain a mutually beneficial outcome for both economic development and ecological protection. Full article

The Global Ecosystem Dynamics Investigation (GEDI) system provides essential data for estimating forest canopy height on a global scale. However, factors such as complex topography and dense canopy can significantly reduce the accuracy of GEDI canopy height estimations. We selected the South Taihang region of Henan Province, China, as our study area and proposed an optimization framework to improve GEDI canopy height estimation accuracy. This framework includes correcting geolocation errors in GEDI footprints, screening and analyzing features that affect estimation errors, and combining two regression models with feature selection methods. Our findings reveal a geolocation error of 4 to 6 m in GEDI footprints at the orbital scale, along with an overestimation of GEDI canopy height in the South Taihang region. Relative height (RH), waveform characteristics, topographic features, and canopy cover significantly influenced the estimation error. Some studies have suggested that GEDI canopy height estimates for areas with high canopy cover lead to underestimation, However, our study found that accuracy increased with higher canopy cover in complex terrain and dense vegetation. The model’s performance improved significantly after incorporating the canopy cover parameter into the optimization model. Overall, the R² of the best-optimized model was improved from 0.06 to 0.61, the RMSE was decreased from 8.73 m to 2.23 m, and the rRMSE decreased from 65% to 17%, resulting in an accuracy improvement of 74.45%. In general, this study reveals the factors affecting the accuracy of GEDI canopy height estimation in areas with complex terrain and dense vegetation cover, on the premise of minimizing GEDI geolocation errors. Employing the proposed optimization framework significantly enhanced the accuracy of GEDI canopy height estimates. This study also highlighted the crucial role of canopy cover in improving the precision of GEDI canopy height estimation, providing an effective approach for forest monitoring in such regions and vegetation conditions. Future studies should further improve the classification of tree species and expand the diversity of sample tree species to test the accuracy of canopy height estimated by GEDI in different forest structures, consider the distortion of optical remote sensing images caused by rugged terrain, and further mine the information in GEDI waveforms so as to enhance the applicability of the optimization framework in more diverse forest environments. Full article

The measurement of groundwater exchange between neighboring regions is a critical topic in water resource management and can usually be achieved through a combination of field investigations and the use of groundwater flow models. In this study, we employed the water balance and Darcy’s law methods, utilizing downscaled Gravity Recovery and Climate Experiment (GRACE) and GRACE-Follow On (GRACE-FO) data to assess groundwater exchange patterns in the Beijing-Tianjin-Hebei (BTH) region of China. Additionally, we determined the contributions of human activities and climate factors to the observed variations via residual analysis. The results revealed a consistent decrease in groundwater storage in the study area since 2008, especially in the spring and summer months. The groundwater exchange rates calculated by 1° and 0.05° groundwater storage anomalies (GWSAs) were basically consistent, and the downscaled GWSAs could better reflect the small-scale groundwater exchange characteristics. The groundwater exchange rate showed a decreasing trend from the Piedmont plain to the coastal areas. A notable trend of declining groundwater exchange between the Taihang Mountains and Piedmont plains was observed, and the downward trend gradually intensified from north to south between 2003 and 2007. After 2008, there was an increasing trend, and coastal areas exhibited the smallest amount of groundwater exchange. Human activities emerged as the predominant factor accounting for more than 90.9% of the overall reduction in groundwater storage, while climate change imposed a minimal influence on groundwater storage variations. The insights obtained in this study hold significant implications for groundwater resource planning and management in the region. Full article

As a major grain-producing region in China, the North China Plain (NCP) faces serious challenges such as water shortage and land subsidence. In late 2014, the Central Route of the South-to-North Water Diversion Project (SNWD-C) began to provide NCP with water resources. However, the effectiveness of this supply in mitigating land subsidence remains a pivotal and yet unassessed aspect. In this paper, we utilized various geodetic datasets, including the Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow On (GRACE-FO), Global Navigation Satellite System (GNSS) and leveling data, to conduct a spatial-temporal analysis of the equivalent water height (EWH) and vertical ground movement in the NCP. The results reveal a noteworthy decline in EWH from 2011 to 2015, followed by a slight increase with minor fluctuations from 2015 to 2020, demonstrating a strong correlation with the water resources supplied by the SNWD-C. The GRACE-derived surface deformation rate induced by hydrological loading is estimated to be <1 mm/yr. In comparison, GNSS-derived vertical ground movements exhibit considerable regional differences during the 2011–2020 period. Substantial surface subsidence is evident in the central and eastern NCP, contrasting with a gradual uplift in the front plain of the Taihang Mountains. Three-stage leveling results indicate that the rate of subsidence in the central and eastern plains is gradually increasing with the depression area expanding from 1960 to 2010. Based on these geodetic results, it can be inferred that the SNWD-C’s operation since 2014 has effectively mitigated the reduction in terrestrial water storage in the NCP. However, land subsidence in the NCP persists, as the subsidence rate does not turn around in sync with the change in EWH following the operation of SNWD-C. Consequently, it’s necessary to maintain and enforce existing policies, including controlling groundwater exploitation and water resources supply (e.g., SNWD-C) to curtail the exacerbation of land subsidence in the NCP. Additionally, continuous monitoring of land subsidence by GRACE, GNSS, leveling and other geodetic techniques is crucial to enable timely policy adjustments based on monitoring results. Full article

As the most unique ecosystem on the Earth’s surface, desert and desertification region cannot be confused. The current research on spatial distinction of desert and desertification region is still lacking. Based on NDVI (normalized difference vegetation index) data from 1998 to 2020, we aimed to distinguish the differences between desert and desertification region. Improvement and degradation of vegetation quality in China have coexisted in the past 20 years. Within the low value classification in 1998, the regions where vegetation quality remained High increase were mainly concentrated in Loess Plateau. Within the medium value classification in 1998, the High increase classifications were mainly distributed in the west of the Taihang Mountains, north of the Qinling–Daba Mountains, east of the Qinghai–Tibet Plateau, Yunnan–Guizhou Plateau, and the Northeast Plain. Within the high value classification in 1998, the High increase classification was distributed in the south of the Yangtze River. In 1998 and 2020, China had a total area of 2.50 million km² of desert regions, accounting for 26% of China’s land area. After 20 years of large-scale ecological protection, desert regions have hardly undergone significant changes. Desertification regions decreased from 2.80 million km² to 1.67 million km², a decrease of 40.3%. Full article

With the rapid development of China’s economy, rural tourism is developing in full swing throughout the country, attracting significant capital inflow with its unique historical features and natural landscapes. In recent years, vernacular architectures are experiencing a spontaneous transformation. The evolution of vernacular architecture presents a development trend of “self-organization”. In order to study the evolution of vernacular architecture in the context of tourism development, the authors consider tourism villages in the southern Taihang area. Samples of rural vernacular architecture were selected, analysing spatial typologies and the theory of self-organization in the development process. Finally, the article finds that the evolving development mechanisms are considered as vernacular architecture of the region shifts from disorder to order. Full article

Clarifying the interrelationship between climate and land use/land cover (LULC) changes on water yield in mountainous areas is very urgent due to the dramatic decrease in the water availability of mountainous areas. In this study, the InVEST model was used to calculate the water yield of the mountainous area in Beijing–Tianjin–Hebei region (BTH) from 1980 to 2020, and six scenarios were designed to identify the contribution rates of climate and LULC change on the water yield. The results showed that, in 1980–2020, the water yield in the mountainous area of BTH was the largest in 1990, at 377.95 mm and the smallest in 1980, at 150.49 mm. After 2000, the interannual water yield showed a slightly increasing trend, which was significantly lower than the water yield in 1990, the values ranging from 217.01 mm to 324.65 mm. During the study period, the spatial distribution of the water yield was similar over the years, with high values in the south-central Taihang Mountain (THM) and the northeastern Yanshan Mountain (YSM). The THM was the main water yield area of the mountainous area in BTH. The annual water yield of farmland was the highest, followed by forest land and grassland, while the proportion of volumetric water yield was the largest in forest land with an increasing trend from 1980 to 2020 and the grassland showed a decreasing trend, while that of farmland increased first from 1980 to 2000 and decreased from 2000 to 2020. Climate is the key factor controlling the water yield of the mountainous area in BTH from 1980–2000, 2000 to 2020, and 1980 to 2020. In the period of 2000–2020, the effect of LULC on the water yield is negative, while the effect is positive in 1980–2000 and 1980–2020. The contribution rate of climate to the water yield increases in the THM, Bashang region (BSR) and YSM from the period 1980–2000 to 2000–2020, while that of LULC in those three regions changes from a positive impact in 1980–2000 to a negative impact in 2000–2020, and the contribution rate is also greatly reduced. In the long term, land revegetation will gradually benefit the water yield in the mountainous areas of BTH, including the THM, BSR, and YSM. These results can provide an important scientific and technological reference for the ecological management and protection of water source sites, as well as the planning and utilization of water resources in mountainous areas of BTH. Full article

China’s “plain–mountain transition zone” (hereinafter referred to as the “transition zone”) has experienced rapid and diverse urbanization processes. Assessing the dynamic characteristics of urbanization is particularly important for sustainable development of the transition zone. Nighttime light (NTL) data have been widely used to monitor urbanization. Based on the prolonged artificial nighttime-light dataset of China (PANDA) from 1984 to 2020, we partitioned the nighttime light of the study area into four types (low, medium, high, and extremely high) by adjusting the threshold of the brightness gradient (BG) method. The spatiotemporal characteristics of urbanization in 426 districts and counties of 71 prefecture-level cities in the transition zone were analyzed. Our results indicated that the middle region of the transition zone (Yanshan Mountains and Taihang Mountains) experienced the fastest urbanization development, and the urban expansion speed broke through the topographic limitation of the plain–mountain. However, the rapid development of urbanization in the middle plains resulted in the nighttime lighting area (NTLA) tending to become saturated, which caused an unsustainable potential crisis in urban development in this area. Urbanization was mainly manifested in the transition of the low nighttime lighting type (NTLT) to the medium NTLT or higher NTLT. The northern region of the transition zone (Greater Khingan Mountains) experienced the slowest urbanization development, with the lowest nighttime lighting density (NTLD) in the northern mountainous area, where the urbanization was mainly manifested by the expansion of the low NTLT. The urbanization development of the southern region in the transition zone (Wushan and Xuefeng Mountains) was at a medium level, and the urbanization of the plain in the southern region was also better than that of the mountainous area. Urbanization was mainly manifested in the expansion of the low NTLT, supplemented by the transition from the low NTLT to high NTLT. Whether in the north, middle, or south of the transition zone, the plain–mountain topographic variations caused a gap in urbanization, making the urbanization development of the mountains and plains unbalanced. Full article

It is well known that there are geometric distortions in synthetic aperture radar (SAR) images when the terrain undulates. Layover is the most common one, which brings challenges to the application of SAR remote sensing. This study proposes a novel detection method that is mainly aimed at the layover caused by mountains and can be performed with only medium-resolution SAR images and no other auxiliary data. The detection includes the following four stages: initial processing, difference image calculation and rough and fine layover detection. Initial processing mainly obtains the potential layover areas, which are mixed with the built-up areas after classification. Additionally, according to the analysis of the backscatter coefficient (BC) of various ground objects with different polarization images, the layover areas are detected step-by-step from the mixed areas, in which the region-based FCM segmentation algorithm and spatial relationship criteria are used. Taking the Danjiangkou Reservoir area as the study area, the relevant experiments with Sentinel-1A SAR images were conducted. The quantitative analysis of detection results adopted the figure of merit (FoM), and the highest accuracy was up to 87.6% of one selected validation region. Experiments in the South Taihang area also showed the satisfactory effect of layover detection, and the values of FoM were all above 85%. These results show that the proposed method can do well in the layover detection caused by mountains. Its simplicity and effectiveness are helpful in removing the influence of layover on SAR image applications to a certain extent and improving the development of SAR remote sensing technology. Full article

Nitrogen dioxide (NO₂) is an important pollutant related to human activities, which has short-term and long-term effects on human health. An ensemble learning model was constructed and applied to estimate daily NO₂ concentrations in the Beijing–Tianjin–Hebei region between 2010 and 2016. A variety of predictive variables included satellite-based troposphere NO₂ vertical column concentration, meteorology, elevation, gross domestic product (GDP), population, land-use variables, and road network. The ensemble learning model achieved two things: a 0.01° × 0.01° grid resolution and the estimation of historical data for the years 2010–2013. The ensemble model showed good performance, whereby the R² of tenfold cross-validation was 0.72 and the R² of test validation was 0.71. Meteorological hysteretic effects were incorporated into the model, where the one-day lagged boundary layer height contributed the most. The annual NO₂ estimation showed little change from 2010 to 2016. The seasonal NO₂ estimation from highest to lowest occurred in winter, autumn, spring, and summer. In the annual maps and seasonal maps, the NO₂ estimations in the northwest region were lower than those in the southeast region, and there was a heavily polluted band in the south of the Taihang Mountains. In coastal areas, the annual NO₂ estimations were higher than the NO₂ monitored values. The drawback of the model is underestimation at high values and overestimation at low values. This study indicates that the ensemble learning model has excellent performance in the simulation of NO₂ with high spatial and temporal resolution. Furthermore, the research framework in this study can be a generally applied for drawing implications for other regions, especially for other cities in China. Full article