Due to the extremely poor soil cover, a low soil-forming rate, and inappropriate intensive land use, soil erosion is a serious problem in Guizhou Province, which is located in the centre of the karst areas of Southwest China. In order to bring soil erosion under control and restore environment, the Chinese Government has initiated a serious of ecological rehabilitation projects such as the Grain-for-Green Programme and Natural Forest Protection Program and brought about tremendous influences on land-use change and soil erosion in Guizhou Province. This paper explored the relationship between land use and soil erosion in the Maotiao River watershed, a typical agricultural area with severe soil erosion in central Guizhou Province. In this study, we analyzed the spatio-temporal dynamic change of land-use type in Maotiao River watershed from 1973 to 2007 using Landsat MSS image in 1973, Landsat TM data in 1990 and 2007. Soil erosion change characteristics from 1973 to 2007, and soil loss among different land-use types were examined by integrating the Revised Universal Soil Loss Equation (RUSLE) with a GIS environment. The results indicate that changes in land use within the watershed have significantly affected soil erosion. From 1973 to 1990, dry farmland and rocky desertified land significantly increased. In contrast, shrubby land, other forestland and grassland significantly decreased, which caused accelerated soil erosion in the study area. This trend was reversed from 1990 to 2007 with an increased area of land-use types for ecological use owing to the implementation of environmental protection programs. Soil erosion also significantly varied among land-use types. Erosion was most serious in dry farmland and the lightest in paddy field. Dry farmland with a gradient of 6°-25° was the major contributor to soil erosion, and conservation practices should be taken in these areas. The results of this study provide useful information for decision makers and planners to take sustainable land use management and soil conservation measures in the area.

Ecological land rent is the excess profit produced by resource scarcity, and is also an important indicator for measuring the social and economic effects of resource scarcity. This paper, by calculating the respective ecological land rents of all the provinces in China for the years 2002 and 2007, and with the assistance of the software programs ArcGIS and GeoDA, analyzes the spatial differentiation characteristics of ecological land rent; then, the influencing factors of ecological land rent differentiation among the provinces are examined using the methods of traditional regression and spatial correlation analysis. The following results were obtained: First, ecological land rent per unit of output in China shows stable distribution characteristics of being low in the southwestern and northeastern provinces, and high in Hebei and Henan provinces. There is also an increasing tendency in the central and western provinces, and a decreasing one in the eastern provinces. In general, the spatial distribution of ecological land rent per unit of output in China is quite scattered. Second, the total ecological land rent shows significant spatial aggregation characteristics, in particular the provinces in China possessing high total amounts of ecological land rent tend to be adjacent to one another, as do those with low total amounts, and the spatial difference characteristics of the eastern, central and western provinces are distinguished. The Bohai Rim, Yangtze River Delta and Pearl River Delta are shown to be highly clustering regions of total ecological land rent, while the western provinces have very low ecological land rent in terms of total amount. Third, population distribution, economic level and industrial structure were all important influencing factors influencing ecological land rent differentiation among provinces in China. Furthermore, population density, urbanization level, economic density, per capita consumption level and GDP per capita were all shown to be positively related to total ecological land rent, which indicates that spatial clustering exists between ecological land rent and these factors. However, there was also a negative correlation between ecological land rent and agricultural output percentage, indicating that spatial scattering exists between ecological land rent and agricultural output percentage.

Based on historical documents and records this paper analyzes the characteristics of frequency and distribution of major disasters that took place in the history of China. The findings show that occurrences of different types of disasters varied and spatial pattern at provincial level are significantly different as well. The results also indicate that there is a strong relationship between type of disasters and spatial distribution and that the spatial pattern of losses was not the same as that of the frequency. The reasons are: (1) the hazard-formative environments which, to a large extent, determine the spatial pattern of the disasters are significantly different; (2) the losses caused by natural disasters were closely related to the concentration of economy and population. Number of deaths was usually large in areas where agriculture, culture and business were relatively developed. The spatial pattern of disaster losses is an evitable result of uneven economic development in the history of China.

According to the meteorological observation data of 72 stations from 1960 to 2010 in the Huanghe (Yellow) River Watershed, China, the long-term variations of potential evapotranspiration, calculated in the modified Penman-Monteith model of Food and Agriculture Organization of the United Nations, were presented, as well as the meteorological causes for the decrease of potential evapotranspiration were discussed. Since 1960, temperature has risen significantly and potential evapotranspiration a decreasing trend, which indicated the existence of “Evaporation paradox” in the Huanghe River Watershed. This phenomenon was not consistent spatially or temporally with the increase of temperature, potential evapotranspiration decreased in spring, summer and winter, mainly over most parts of Shanxi and Henan, and some parts of Gansu, Ningxia, Inner Mongolia, and Shaanxi. During the recent half century, the trends of temperature and potential evapotranspiration were negatively correlated at most of the stations, while precipitation and potential evapotranspiration exhibited a contrary trend. Calculated in multiple regressions, the contribution to potential evapotranspiration change of related meteorological factors was discussed, including mean pressure, maximum and minimum temperature, sunshine hours, relative humidity and average wind speed. The decrease of wind speed in the Huanghe River Watershed may be the dominating factor causing potential evapotranspiration decreasing.

Water discharge data of the Yellow River over the past 60 years was analyzed using the continuous wavelet transform (CWT) and Mann-Kendall (MK) test methods to identify spatial and temporal variation patterns. Potential connections between water discharge in the Yellow River Basin and El Niño/Southern Oscillation (ENSO) were also examined by the cross wavelet and wavelet coherence methods. CWT results show that the periodic oscillations in water discharges had occurred at the temporal scales of 1-, 2- to 4-, 6- to 8- and 10- to 22-year. It was also found that at the annual timescale (1-year) the phase relations between water discharge and ENSO were indistinct probably due to the strong influence by human disturbances. However, over the longer time scales, the phase relation becomes much clearer with an anti-phase relation being found mainly at inter-annual scale (2- to 8-year) and in-phase relation at decadal scale (16- to 22-year). According to the MK test results water discharge at most stations except Tangnaihai have decreased significantly and the abrupt change occurred in the mid-1980s or the early 1990s. The changes in water discharge were found to be influenced by both climate changes and human activities. Before 1970 the change in water discharge was positively related to precipitation variations in the river basin, but after 1970 the decrease in water discharge has been largely caused by various human activities including constructions of reservoirs, water abstraction and water-soil conservation with water abstraction being the main cause.

Based on the glacier area variation records in the typical regions of China monitored by remote sensing, as well as the meteorological data of air temperature and precipitation from 139 stations and the 0℃ isotherm height from 28 stations, the glacier area shrinkage in China and its climatic background in the past half century was discussed. The initial glacier area calculated in this study was 23,982 km² in the 1960s/1970s, but the present area was only 21,893 km² in the 2000s. The area-weighted shrinking rate of glacier was 10.1%, and the interpolated annual percentage of area changes (APAC) of glacier was 0.3% a^-1 since 1960. The high APAC was found at the Ili River Basin and the Junggar Interior Basin around the Tianshan Mountains, the Ob River Basin around the Altay Mountains, the Hexi Interior Basin around the Qilian Mountains, etc. The retreat of glacier was affected by the climatic background, and the influence on glacier of the slight-increased precipitation was counteracted by the significant warming in summer.

Based on the meteorological data of 20 stations in the Hengduan Mountains region during 1961-2009, the annual and seasonal variation of potential evapotranspiration was analyzed in combination with the Penman-Monteith model. With the method of Spline interpolation under ArcGIS, the spatial distribution of potential evapotranspiration was presented to research the regional difference, and the correlation analysis was used to discuss the dominant factor affecting the potential evapotranspiration. The results indicated that the annual potential evapotranspiration showed a decreasing tendency since the 1960s, especially from the 1980s to 1990s, while it showed an increasing tendency since 2000. Regional potential evapotranspiration showed a rate of -0.17 mm a^-1. Potential evapotranspiration in north, middle and south of the Hengduan Mountains exhibited decreasing trends over the studied period, and its regional trend was on the decline from southwest to northeast.

Study on regional carbon emission is one of the hot topics under the background of global climate change and low-carbon economic development, and also help to establish different low-carbon strategies for different regions. On the basis of energy consumption and land use data of different regions in China from 1999 to 2008, this paper established carbon emission and carbon footprint models based on total energy consumption, and calculated the amount of carbon emissions and carbon footprint in different regions of China from 1999 to 2008. The author also analyzed carbon emission density and per unit area carbon footprint for each region. Finally, advices for decreasing carbon footprint were put forward. The main conclusions are as follows: (1) Carbon emissions from total energy consumption increased 129% from 1999 to 2008 in China, but its spatial distribution pattern among different regions just slightly changed, the sorting of carbon emission amount was: Eastern China > Northern China > Central and Southern China > Southwest China > Northwest China. (2) The sorting of carbon emission density was: Eastern China > Northeast China > Central and Southern China > Northern China > Southwest China > Northwest China from 1999 to 2003, but from 2004 Central and Southern China began to have higher carbon emission density than Northeast China, the order of other regions did not change. (3) Carbon footprint increased significantly since the rapid increasing of carbon emissions and less increasing area of productive land in different regions of China from 1999 to 2008. Northern China had the largest carbon footprint, and Northwest China, Eastern China, Northern China, Central and Southern China followed in turn, while Southwest China presented the lowest area of carbon footprint and the highest percentage of carbon absorption. (4) Mainly influenced by regional land area, Northern China presented the highest per unit area carbon footprint and followed by Eastern China, and Northeast China; Central and Southern China, and Northwest China had a similar medium per unit area carbon footprint; Southwest China always had the lowest per unit area carbon footprint. (5) China faced great ecological pressure brought by carbon emission. Some measures should be taken both from reducing carbon emission and increasing carbon absorption.

Urban clusters are the expected products of high levels of industry and urbanization in a country, as well as being the basic units of participation in global competition. With respect to China, urban clusters are regarded as the dominant formation for boosting the Chinese urbanization process. However, to date, there is no coincident, efficient, and credible methodological system and set of techniques to identify Chinese urban clusters. This research investigates the potential of a computerized identification method supported by geographic information techniques to provide a better understanding of the distribution of Chinese urban clusters. The identification method is executed based on a geographic information database, a digital elevation model, and socio-economic data with the aid of ArcInfo Macro Language programming. In the method, preliminary boundaries are identified according to transportation accessibility, and final identifications are achieved from limiting city numbers, population, and GDP in a region with the aid of the rasterized socio-economic dataset. The results show that the method identifies nine Chinese urban clusters, i.e., Pearl River Delta, Lower Yangtze River Valley, Beijing-Tianjin-Hebei Region, Northeast China Plain, Middle Yangtze River Valley, Central China Plains, Western Taiwan Strait, Guanzhong and Chengdu-Chongqing urban clusters. This research represents the first study involving the computerized identification of Chinese urban clusters. Moreover, compared to other related studies, the study's approach, which combines transportation accessibility and socio-economic characteristics, is shown to be a distinct, effective and reliable way of identifying urban clusters.

Swidden agriculture is by far the dominant land use system in the uplands of Southeast Asia (SEA), as well as other tropical regions, which plays an important role in the implementation of Reducing Emissions from Deforestation and Forest Degradation (REDD) of United Nations. To our knowledge, the long-term inter-annual area of newly burned plots (NBP) of swidden agriculture in mainland Southeast Asia is still not available, let alone in the whole tropics. With the strengthening regional geo-economic cooperation in SEA, swidden agriculture has experienced and/or is still experiencing extensive and drastic transformations into other diverse market-oriented land use types since the 1990s. In this study, high-level surface reflectance products of Landsat 4/5/7/8 family sensors including Thematic Mapper (TM), Enhanced Thematic Mapper Plus (ETM+) and Operational Land Imager (OLI) acquired in March, April and May of each year between 1988 and 2016 were firstly utilized to detect and monitor the extent and area of NBP of swidden agriculture with multiple thresholds of four commonly-used vegetation indices, namely the Normalized Difference Vegetation Index (NDVI), Normalized Difference Moisture Index (NDMI), Normalized Burn Ratio (NBR) and Soil Adjusted Vegetation Index (SAVI), in combination with local phenological features of swiddening and topographical data. The results showed that: (1) an annual average of 6.08×10⁴ km² of NBP of swidden agriculture, or 3.15% of the total land area of MSEA, were estimated in the past nearly three decades. (2) Annual NBP were primarily distributed in four major geomorphic units including the Central Range of Hills, Northern Mountainous Region, Western Myanmar Hills, and Annamite Chain. (3) A decadal average analysis indicated that the NBP of swidden agriculture opened year by year declined as a whole, especially after 2010, merely with an average of 5.23×10⁴ km². (4) The top ten provincial administrative units in Cambodia, Laos, Myanmar, Thailand and Vietnam, which consistently accounted for over 90% of the newly opened swiddens of each country, showed distinct fluctuations in using slash-and-burn practices in the last decades. The Landsat-based (30 m) reconstructed 29-year longitudinal updated maps (including extent and area) of the NBP of swidden agriculture may contribute to REDD and local livelihood related studies in Continental Southeast Asia. Our study further demonstrated that the multiple vegetative indices thresholds approach holds great potential in detecting swidden agriculture in tropical mountainous regions.

This paper quantitatively analyzes the utilization efficiency of agricultural resources in Central Asia by calculating the consumption coefficient of the main resources, including arable land, water and fertilizers. The results of these investigations reveal the following: (1) The average consumption coefficients of cultivated land resources in Central Asia are much higher than the world average value of up to 7.74 m²/kg, which is 3.6 times that of China, suggesting that the cultivated land resource consumption coefficient of cultivated land resource utilization efficiency is low in the Central Asian region. (2) Up to 80% of available water resources are used for agriculture irrigation. The average agricultural water consumption in Central Asia is about 9.43 m³/kg, or nearly 9.3 times the average value elsewhere in Asia, indicating that agricultural water use efficiency in this region is very low and water resources are wasted. (3) The fertilizer consumption coefficient in Central Asia is 0.035 kg/kg, which is close to the world average, but the utilization efficiency of fertilizer is relatively high. Therefore, in the future development of agriculture, Central Asia should pay more attention to the management of agricultural water resources in order to improve the utilization efficiency of these resources as well as that of arable land.

Settlements are excellent spatiotemporal indicators for studying historical human activities and environmental change. This paper discusses the spatial and temporal changes of sites on the Ordos Plateau in China since the Neolithic Age, based on an analysis of spatiotemporal distribution characteristics of the human settlements. The frequency of human settlements on the Ordos Plateau presented a phased fluctuation process, and the sizes were mainly small and medium. The spatial distribution of human settlements was fractal, and the D value of the aggregation dimension was generally small, indicating that the spatial distribution of the sites was agglomerated. Affected by the desert, the sites were mainly distributed in the south and east of the Ordos Plateau. The spatiotemporal distribution pattern of human settlements in the Ordos Plateau resulted from the combined action of natural and human factors, especially climate change. Moreover, local livelihood patterns significantly affected the frequency of human settlements. The number of human settlements in the farming period was large, and the distribution was concentrated. In contrast, the number of sites in the nomadic period was small and scattered. The central government’s policies and the conflicts between farming and nomadic groups further affected the spatiotemporal distribution of human settlements. This study may contribute to a better understanding of historical environmental change and human-land relationships in the Ordos Plateau.

China's rural territory is entering a critical stage of transformation and development. Promoting rural development and transformation is an important path to achieve rural vitalization, and land consolidation is expected to become the starting point to boost rural transformation. To clarify the internal relationship between land consolidation and rural development transformation is an important scientific proposition. This paper constructs a theoretical framework of rural land consolidation (RLC) affecting rural development transformation (RDT), and analyzes the historical evolution process and characteristics of RLC and rural development in China. Based on government interviews and household surveys, this paper analyzes the impact of RLC on RDT under different geographic types and different consolidation models from a multi-subject perspective, and empirically tests the effects using the econometric model. China's rural land consolidation has also gradually transformed to multi-type and multi-functional comprehensive consolidation. The results show that there are many explicit and implicit mechanisms of the influence of RLC on RDT in China, such as mechanism of promotion of industrial development, mechanism of integration of development factors, mechanism of urbanization and mechanism of urban-rural interaction. And the results of different modes of RLC impact on RDT are different. Farmers have a high degree of support and satisfaction with RLC since RLC has improved their production and living conditions as well as household and village income. Besides, the effects of various types of RLC on RDT are positive. The authors argue that constructing human-land early warning mechanisms, optimizing the layout and performance evaluation of RLC and promoting multi-type development and multisystem coordination of RLC can elevate the effect of RLC on RDT. This paper provides reference for scientific decision-making of RDT from the perspective of RLC.

The simulation of intercity population mobility helps to deepen the understanding of intercity population mobility and its underlying laws, which has great importance for epidemic prevention and control, social management, and even urban planning. There are many factors that affect intercity population mobility, such as socioeconomic attributes, geographical distance, and industrial structure. The complexity of the coupling among these factors makes it difficult to simulate intercity population mobility. To address this issue, we propose a novel method named the quantum harmonic oscillator model for simulation of intercity population mobility (QHO-IPM). QHO-IPM describes the intercity population mobility as being affected by coupled driving factors that work as a multioscillator-coupled quantum harmonic oscillator system, which is further transformed by the oscillation process of an oscillator, namely, the breaking point of intercity population mobility. The intercity population mobility among seven cities in the Beijing-Tianjin-Hebei region and its surrounding region is taken as an example for verifying the QHO-IPM. The experimental results show that (1) compared with the reference methods (the autoregressive integrated moving average (ARIMA) and long and short-term memory (LSTM) models), the QHO-IPM achieves better simulation performance regarding intercity population mobility in terms of both overall trend and mutation. (2) The simulation error in the QHO-IPM for different-level intercity population mobility is small and stable, which illustrates the weak sensitivity of the QHO-IPM to intercity population mobility under different structures. (3) The discussion regarding the influence degree of different driving factors reveals the significant “one dominant and multiple auxiliary” factor pattern of driving factors on intercity population mobility in the study area. The proposed method has the potential to provide valuable support for understanding intercity population mobility laws and related decision-making on intercity population mobility control.

Climate change and rapid urbanization pose significant challenges to the conservation and management of agricultural heritage systems, including decline in agricultural land, loss of labor, and ecosystem degradation. Although existing studies have proposed general strategies with theoretical guidance and specific strategies for particular systems to promote the conservation of agricultural heritage systems, there remains a large knowledge gap in effective and differentiated management strategies at the regional level. This is especially so in China because of the clear regional differences in the natural and socioeconomic conditions of the widely distributed China Nationally Important Agricultural Heritage Systems (China-NIAHS). In this study, we integrated multi-source data and spatial analysis to reveal the distribution characteristics of existing China-NIAHS and proposed differentiated management strategies. Results show that there are four clustering distribution zones of China-NIAHS, i.e., the northwest clustering zone west of the Heihe-Tengchong Line (Zone I), the clustering belt with ‘Northeast-Hebei-Shandong’ as core (Zone II), the Yangtze River Delta clustering zone (Zone III), and the Hunan-Chongqing-Yunnan-Guizhou clustering zone (Zone IV). Different management strategies are proposed for the China-NIAHS in each clustering zone. Specifically, Zone I should focus on maintaining their ecological functions and services, while Zone II should aim for livelihood supply, sustainable resource use, and ecological protection. For Zone III, rapid urbanization could become a positive driving force for China-NIAHS conservation through sustainable tourism and reasonable urban zoning. Zone IV should emphasize the mutual support between characteristic product development and the brand effect of the China-NIAHS. These findings will help establish regional and targeted management strategies for China-NIAHS and provide a reference for the conservation of agricultural heritage systems in other countries.

The main aims of the current study are to determine the morphological features of the periglacial landforms (non-sorted step, mud circle, stony earth circle, thufur, and congeliturbation) located on the Ilgaz Mountains, examine the physicochemical and mineralogical properties with pedological processes of the soils, and assess of the effects of climatic conditions controlling the development of landforms. The Ilgaz Mountains (2587 m a.s.l.), located in the Western Black Sea Region, within the Anatolian Mountains, are important in terms of periglacial landforms (mud circles, stony earth circles, thufurs, non-sorted steps, non-sorted stripes, congeliturbation deposits, and block currents). The descriptive statistics of 123 periglacial landforms measured by fieldworks were analyzed. The distribution of freezing and thawing in the Ilgaz Mountains throughout the year was evaluated, and it was found that freezing takes place between December and March, freezing-thawing takes place in April, May, October and November, and thawing takes place between June and October. According to soil properties, organic matter content changes from 1.88% to 12.72% in non-sorted step soils, while it is between 2.03% and 12.24% in stony earth circle soils. The organic matter is observed to be close to congeliturbation deposits at lower ratios compared to non-sorted steps, stony earth circles and mud circles. The soil reactions on stony earth circles and non-sorted steps vary between slightly acidic and slightly alkaline. On the other hand, soil samples taken from the mud circles are different from those taken from the non-sorted steps and stony earth circles. Their soil reaction is acidic, and pH changes between 4.86 and 6.25. The lime content also varies between 2.81% and 32.08%, with an average of 12.02%. The texture properties of soils are dominantly loam and clay loam, as in the non-sorted steps, stony earth circles, and mud circles. Considering their mineralogical properties, the XRD study was carried out to determine the primer mineral types and abundance degrees of soils of periglacial landforms. Quartz, muscovite and albite minerals were found in soils in the stony earth circle, while quartz, muscovite, orthoclase and albite minerals were determined as primary minerals in soils formed on the thufur landforms.

As China's Loess Plateau has lately witnessed increasingly extreme precipitation events, it is important to analyze the impact of extreme precipitation and identify the conditions for the occurrence of geological disasters. Field surveys can provide detailed geological information in this regard but are time consuming and labor intensive. In this paper, we provide a case study on the Gutun catchment of Yan'an, which was affected by prolonged heavy rainfall in July 2013. We used Digital Elevation Model (DEM) data obtained by processing ZY-03 stereo-pair images before and after the rainy season, including the period of prolonged heavy rainfall mentioned above, to analyze the topographical changes triggered by the rainfall. The results showed the following: (1) The rainy season reduced the elevation of the catchment by about 1.7 cm. The major change in its elevation ranged from -0.5 to 0 m, accounting for 38.41% of the overall area of change and dominating above 70 m of slope height. (2) The rainy season increased the average inclination of the slopes in the area from 28.81° to 28.95°, while the range of their peak inclination was mainly distributed in the range of 24°-36°. (3) Sunny and half-sunny slopes exhibited a greater loss in elevation, while shady and half-shady slopes exhibited an increase in elevation. More drastic topographical changes were observed in the shady and half-shady slopes. (4) The morphology of the area that had undergone a reduction in elevation was characterized by concave slopes, while convex slopes abounded in the area with increased elevation. (5) The sunny or shady properties of the slope aspect constituted the key factor influencing the topographical changes, followed by the height, inclination, and shape of the slopes. The work here can provide guidance for measures related to disaster prevention and mitigation.

This study focuses on the Lower Yellow River (LYR), which has experienced continuous erosion since the operation of Xiaolangdi Reservoir in 1999, and its spatiotemporal variation process is complex. Based on the single-step mode of the Delayed Response Model (DRM), we proposed a calculation method for simulating the accumulated erosion and deposition volume in the LYR. The coefficient of determination R² between the calculated and measured values from 2000 to 2020 is 0.99. Currently, the LYR is undergoing continuous erosion, however the erosion rate is gradually slowing down, and the difference between the equilibrium and calculated values of accumulated erosion and deposition volume gradually decreases, which means riverbed erosion has a tendency towards equilibrium. Additionally, we derive a formula to simulate the spatial distribution of the main channel accumulated erosion volume per unit river length in the LYR based on the non-equilibrium suspended sediment transport equation. The coefficient of determination R² between the fitted values and measured values from 2003 to 2015 is approximately 0.98-0.99, with a relative error of approximately 6.2%. The findings in this research suggest that under the current background of decreasing sediment inflow and continuous erosion in the LYR, it takes approximately 3.0 years for the riverbed to achieve half of the erosion and deposition adjustment and approximately 13.0 years to achieve 95% of the adjustment. Moreover, the spatial distribution of accumulated main channel erosion volume in the LYR tends to become uniform with the continuous development of erosion. These results could provide a valuable reference for analysing the complex spatiotemporal variation process in the LYR.

In the present study, indoor experiments were carried out to investigate the effects of rainfall on subsequent wind erosion processes on the simulated Gobi surface, with soils and gravels collected from the Alax Gobi in northwestern China. The results showed that the wind erosion rate (WR) ranged from 0.4 to 1931.2 g m^-2 min^-1 and that the sediment transportation rate (STR) ranged from 0.00 to 51.47 g m^-2 s^-1 under different gravel coverage conditions (0%, 20%, 40% and 60%) when the wind velocity changed from 6 m s^-1 to 18 m s^-1. Both WR and STR increased with increasing wind velocity as a power function and decreased with increasing gravel coverage. The rainfall event had significant inhibitory effects on WR and STR, and the complex effects of soil crust formation and the changing soil surface roughness (SSR) by rainfall event played significant roles in reducing these rates during subsequent wind erosion. In this study, a valuable exploration of the effects of rainfall events on subsequent wind erosion processes in the Gobi area was conducted. The findings are of great significance for a better understanding and effective prediction of dust emissions in this region.

The Yellow River Basin (YRB) is a vital ecological zone in China owing to its sensitive and fragile environment. Under the long-term influence of climate changes and artificial factors, the relationship between precipitation, vegetation, and surface water in the YRB has changed drastically, ultimately affecting the water resources and environmental management. Therefore, we applied multivariate statistical analysis to investigate the precipitation, normalized difference vegetation index (NDVI), and surface water changes in the YRB from 2000 to 2021. Furthermore, we attempted to clarify the ecological effects of precipitation by explaining the relationship between precipitation and vegetation in terms of the time-lag relationship using the Integrated Multi-satellite Retrievals for Global Precipitation Measurement algorithm, Moderate Resolution Imaging Spectroradiometer, and hydrological databases. Precipitation, vegetation, and area of surface water in the YRB showed increasing trends from 2000-2021 (e.g., 7.215 mm/yr, 0.004 NDVI/yr, and 0.932 km²/yr, respectively). The water level in the upper reaches of the YRB showed a downward trend, whereas that in the middle and lower reaches exhibited an upward trend. Changes in precipitation had a positive effect on vegetation and surface water in the YRB, with correlation coefficients of 0.63 and 0.51, respectively. The responses of NDVI and surface water elevation to precipitation were heterogeneous and delayed, with the majority showing a lag time of approximately ≤ 16 days. Moreover, the lag times of Longyangxia Lake and Ngoring-Co Lake were 0 and 8 days, respectively. We showed that precipitation variability can effectively explain vegetation improvement and increases in surface water elevation, while providing a proven scenario for predicting the surface water and vegetation productivity under the influence of climate change.

Population exposure is a dominant representation of rainstorm hazard risks. However, the refined precipitation data in temporal resolution and the comparison of exposure to different rainstorm events remain relatively unexplored. Hourly precipitation data from 165 meteorological stations w used to investigate the spatiotemporal evolution of population exposure to different rainstorm scenarios in the prefecture-level cities for different periods and age groups. The Geographical Detector was adopted to quantitatively analyze the influencing factors and contribution rates to changes in population exposure during each period. The results revealed that population exposure to persistent rainstorms and abrupt rainstorms was low in the center and high in the surrounding areas, and the high exposure value decreased significantly in the 2010s. Additionally, as the duration of rainstorm events increased, the center of the high-value area of population exposure shifted southward. The distribution of population exposure was closely related to the age structure, demonstrating strong consistency with the distribution of different age groups. Except for abrupt rainstorms, the contribution rates of the average land GDP and urbanization rate to the exposure of all rainstorm scenarios increased significantly. This implies that the main factors influencing population exposure have shifted from meteorological to socioeconomic factors.

Significant spatiotemporal variation in human livelihood patterns and its relationship to trans-Eurasian exchange and climate change in north China during the late Neolithic and Bronze Age, has been intensively studied in recent years, but the comprehensive influence of natural and social factors on this variation is not well understood. Therefore, we analyze archaeobotanical, zooarchaeological and carbon isotopic data from late Neolithic and Bronze Age sites in agricultural, pastoral, and agro-pastoral regions of north China. Our results demonstrate human subsistence strategies transformed at different speeds in these three geographic areas after wheat, barley, and sheep, goats, and cattle were introduced into north China. Introduced crops and livestock dominated human livelihoods in pastoral regions and became important subsistence in areas above ~1500 m a.s.l. in agro-pastoral regions after ~3600 BP. In agricultural regions, indigenous millet crops were the most important subsistence throughout 6000- 2200 BP, but wheat use increased significantly around 2700 BP. Our study suggests that the introduction of new crops and herbivorous livestock related to the prehistoric trans-Eurasian exchange, and their adaptive advantage in high-cold environments might have rapidly facilitated human adaptability and social development in pastoral regions and northwest margin of agro-pastoral regions during the Bronze Age.

In recent years, cropland development in high-slope regions in China has alleviated the contradiction between total cropland balance and insufficient development space. However, this change in cropland slope brings risks to sustainable resource utilization. This study explored the slope characteristics of cropland in China from 1990 to 2020 and assessed the gained cropland stability. The results showed that (1) From 1990 to 2020, the lost cropland area was greater than the gained area, and the distribution showed an uphill trend. (2) The areas with a significant upslope change in cropland were mainly concentrated in the southern plain, containing the central grain-producing regions at its core and other well-developed eastern coastal areas. (3) The areas with distinct downslope cropland changes were mainly concentrated in the upper reaches of the Yangtze and Yellow rivers and the ecologically fragile areas of Inner Mongolia and the Loess Plateau. (4) The gained cropland stability was unsatisfactory; about one-third of the gained cropland was unstable, which had the highest abandonment rate within 5 years, and the gained cropland stability decreased with the slope. In addition, this study explored cropland conversion types at different slopes in different regions and discussed the reasons for slope cropland changes and gained cropland instability in different regions. Finally, optimization policies were proposed to protect and control newly gained cropland.

Different types of urban construction land are different in terms of driving factors for their expansion. Most existing studies on driving forces for urban construction land expansion have considered the construction urban land as a whole and have not examined and compared the differentiated driving forces for different types of construction land expansion. This study explored the differentiated driving mechanisms for two types of urban construction land expansion by selecting key driving factors and using spatial econometric regression and geographical detector models. The results show that there are significant differences in the driving forces for expansion between the two types of urban construction land. The driving factors of urban land expansion do not necessarily affect industrial parks. And the factors acting on expansion of both types are different in influence degree. For urban expansion, economic density growth, the value-added growth of tertiary industries, and proximity to urban centers have a negative effect. However, urbanization levels and value-added growth of secondary industries have a positive effect. The explanatory power of these factors is arranged in the following descending order: value-added growth of tertiary industries, value-added change of secondary industries, urban population growth, economic density growth, and proximity to urban centers; road network density has no significant effect. For industrial parks expansion, the value-added growth of secondary industries and road network density has a positive effect, while economic density growth has a negative effect. The explanatory power is arranged in the following descending order: value-added growth of secondary industries, road network density, and economic density growth. The findings can help implement differentiated and refined urban land use management policies.

Cultivated land plays a pivotal role in ensuring national food security, particularly in populous nations like China, where substantial investments are made to develop cultivated land as a counterbalance to construction-occupied areas. Consequently, long-term, effective monitoring of the utilization of newly cultivated land becomes imperative. This study introduces a comprehensive monitoring framework, designed for refined scales, that leverages remote sensing data. The framework focuses on the sustainable utilization of newly cultivated land, emphasizing utilization sustainability, productivity stability, and landscape integration. Its effectiveness was validated through a case study in Guangdong province, China. The results revealed satisfactory utilization sustainability and improved productivity stability of newly cultivated land in Guangdong, though landscape integration showed sub-optimal results. Furthermore, the comprehensive evaluation categorized the newly cultivated land into three levels and eight types. The study recommends enhancing the site selection process for newly cultivated land and improving the long-term monitoring, as well as incentive and constraint mechanisms, for their utilization. This study can provide a scientific reference to bolster the implementation of cultivated land protection policies, thereby contributing significantly to high-quality economic and social development.

This research aimed to understand supply and demand in the global nickel market from a product chain perspective. Accordingly, we established an extensive time-series database for the nickel trade network and employed network analysis methods to explore the dynamics and shifts in the global nickel trade network. The results are as follows: first, refined nickel and nickel semis dominated global nickel trade; second, the interaction between different nickel product networks profoundly affected the global nickel supply chain; third, the global nickel trade network consisted of core-periphery structures exhibiting different degrees of spatial heterogeneity; and fourth, the most connected global backbone structure was in nickel semis, followed by refined nickel, nickel ore, and nickel scrap. Together, trade in these four products constituted an overall network topology characterized by complex forms, a clear hierarchy, and uneven development. We conclude the paper by making several recommendations to secure global nickel supply chains and promote nickel circular economy.

Based on the data of listed companies in the core industry chain of China's new energy vehicles in 2015 and 2021, this paper constructs their industrial network from the perspective of the value chain, and uses methods such as social network and negative binomial regression model to study the characteristics, evolution, differences, and formation mechanisms of different value chain networks. The results show that: (1) R&D-oriented, production-oriented, and service-oriented networks share several common features: These networks are simultaneously expanding in scale and transitioning towards more efficient “small world” network; The degree distribution in these networks follows a power-law distribution, indicating a scale-free network structure; There is a decrease in the power-law exponent of network’s degree distribution, indicating an increase in network heterogeneity. Furthermore, there is a significant positive correlation between the degrees of nodes in networks with diverse value chains, suggesting that the same node holds a similar level of significance across different networks. (2) The number of power-prestige, power and prestige nodes increases in the networks of all value chain segments, except in the service-oriented network, where there are no power nodes. In each value chain network, these nodes have different agglomeration directions: In R&D-oriented network, the nodes tend to cluster around headquarters and high-level cities. In contrast, service-oriented network shows a concentration of nodes in municipalities, sub-provincial and provincial capitals. Similarly, production-oriented network demonstrates a clustering of nodes in traditional production bases. (3) Different value-added segments of industry form different types of agglomeration in pursuit of different factor endowments and agglomeration effect, and form the spatial structure of the strongest connection industrial network with different characteristics. The R&D-oriented networks have always been an integrated and closely connected multiple core-periphery structure community with the influence of social, technological and geographical proximities; Transformation of service-oriented network from an integrated and closely connected multiple core-periphery structure community to a multiple core-semi-periphery-periphery structure community with the influence of social, geographical and institutional proximities; Transformation of production-oriented network from the partially integrated and localized core-periphery structure community to the more decentralized multiple independent core-periphery structure community with the influence of the social, institutional of administrative boundaries and geographical proximities.

Based on investigations between 1986 and 1996 in the four provinces of northern China, major problems on land reclamation were discovered. The increase of arable land was mainly low quality fields from barren land and was susceptible to disertification and water-induced soil erosion. In the meantime, large area of grassland and forestland was lost or degraded, and original fertile arable land was occupied for residential and industrial use. As a result the environment deteriorated. This change was mainly caused by economic development, population growth, inferior natural conditions, and irrational management strategies. Finally some positive measures were suggested to stop this negative cycle.

According to the principle of the eruption of debris flows, the new torrent classification techniques are brought forward. The torrent there can be divided into 4 types such as the debris flow torrent with high destructive strength, the debris flow torrent, high sand-carrying capacity flush flood torrent and common flush flood by the techniques. In this paper, the classification indices system and the quantitative rating methods are presented. Based on torrent classification, debris flow torrent hazard zone mapping techniques by which the debris flow disaster early-warning object can be ascertained accurately are identified. The key techniques of building the debris flow disaster neural network (NN) real time forecasting model are given detailed explanations in this paper, including the determination of neural node at the input layer, the output layer and the implicit layer, the construction of knowledge source and the initial weight value and so on. With this technique, the debris flow disaster real-time forecasting neural network model is built according to the rainfall features of the historical debris flow disasters, which includes multiple rain factors such as rainfall of the disaster day, the rainfall of 15 days before the disaster day, the maximal rate of rainfall in one hour and ten minutes. It can forecast the probability, critical rainfall of eruption of the debris flows, through the real-time rainfall monitoring or weather forecasting. Based on the torrent classification and hazard zone mapping, combined with rainfall monitoring in the rainy season and real-time forecasting models, the debris flow disaster early-warning system is built. In this system, the GIS technique, the advanced international software and hardware are applied, which makes the system's performance steady with good expansibility. The system is a visual information system that serves management and decision-making, which can facilitate timely inspect of the variation of the torrent type and hazardous zone, the torrent management, the early-warning of disasters and the disaster reduction and prevention.

By analysis of published papers on the Yangtze estuary and hydrological and sediments data in Yangshan Harbor area, many similarities are found between Yangshan Harbor area and the Yangtze estuary. These similarities include the phenomenon of stagnating flow areas, the distributive characteristics of the highest suspended sediment concentration areas, superficial sediments and shoal bars. The stagnating flow area is the major similarity which causes other similarities. These similarities indicate that: 1) Turbidity Maximum and mouth bars in estuaries are mainly caused by the hydraulic balance of stagnating flow areas of estuaries; 2) The stagnating sand area of sands caused by stagnating flow area often locates on the narrower side of the stagnating flow area; 3) The location (or shape) of fine sediments area caused by stagnating flow area reflects the location (or shape) of the stagnating flow area. Both Yangshan Harbor area and the Yangtze estuary are the important developmental areas in the future (man-made similarity). In-depth studies on these similarities between Yangshan Harbor area and the Yangtze estuary will have momentous theoretical and practical significance.