The development of industrialization and urbanization has intensified the coupling of human activities and hydrological processes and promoted the emergence of socio-hydrology. This paper addresses the issue of socio-hydrology due to new development and social demand for hydrological sciences and sustainable development. Four key scientific issues are identified through systematic analysis and summary of the relative research and international progress, i.e., (1) the long-term dynamic process of socio-hydrological system evolution; (2) quantitative description and driving mechanism analysis of socio-hydrological coupling system; (3) prediction of the trajectories of socio-hydrological system co-evolution, and (4) integrated water resource management from the perspective of water systems. Moreover, opportunities and challenges for developing socio-hydrology are emphasized, including (1) strengthening the research of interdisciplinary theoretical systems; (2) improving and broadening socio-hydrological research technical methods, and (3) supporting integrated water resources management (IWRM) for sustainable utilization goals (SDGs). The review is expected to provide a reference for the future development of socio-hydrology discipline.

China’s Belt and Road Initiative (BRI) presents the world with a new era of inclusive globalization, which will shape urbanization patterns globally. This study considered the launch of BRI as a quasi-experiment, where we evaluated the BRI’s impact on urbanization by way of difference-in-differences (DID) and propensity score matching (PSM) methods. The results showed that the BRI exerted a significantly negative effect on urbanization in its first three years. Its positive effect emerged from the fifth year onwards, indicating that the BRI’s positive effect on urbanization required a period of practical experience. Heterogeneous analysis and placebo test were also conducted to verify the robustness of the model. The effects in low-income countries were revealed to have been much greater than in high-income countries, meaning the BRI had been conducive to promote local urban growth in underdeveloped economies. Finally, the geographical detector model was introduced to discuss the influencing mechanism of urbanization in BRI and non-BRI countries, showing external factors were the prominent driving forces in BRI countries, whereas internal drivers played an important role in non-BRI countries. Our findings indicated that the implementation of the BRI contributed to building global economic growth and supporting a shared future.

Based on development data relating to China-Africa International Cooperation Parks (CAICPs) from 2003 to 2018, this study examined the transnational investment network of CAICPs using the social network analysis method. The number of CAICPs is increasing. Textiles and apparel, agricultural and food processing, trade logistics and management, building materials and construction, and electrical machinery and equipment manufacturing are the leading industries chosen by most CAICPs. These parks have promoted the economic and social development of African countries, driving the urbanization of the regions in which the parks are located, and they have also benefited China. The network of CAICPs involves China, African countries, and third-party investors. The network is becoming increasingly complex and has an increasingly high density. However, the key node countries and provincial units remain relatively stable despite changes in the network structure. The center of gravity of the network has shown noticeable deviations and regression, and inter-provincial investment cooperation has also been increasing. China-Africa cooperation drives the evolution of the network. In China, the investment of enterprises in Africa is affected by domestic policy, economic pursuit, and investment security. In Africa, the development of CAICPs is driven by development policies and achievements, and it is influenced by African countries’ business environments.

The agricultural regional type and function are the key theoretical issues in agricultural geography research. Gully agriculture in the Loess Plateau is a new regional type of agricultural system with the coupling development of the modern gully human-earth relationship. The study of its functional changes is of great practical significance for food security, rural revitalization and sustainable development of regional agriculture in the region of interest. This paper analyses the multifunctional change of gully agriculture in the Loess Plateau and its dynamic mechanism by using large-scale remote sensing data, topographic relief amplitude model, and spatial econometric model to understand internal implications for evolution differentiation at the basin level. The results show that: (1) The spatial concentration of production and supply function of agricultural products (APF) in the gully of the Loess Plateau gully is high, while the ecological conservation and maintenance function (ECF), employment and social security function (ESF), cultural heritage and leisure function (CRF) are relatively low. The four functions’ spatial distribution has revealed an apparent regularity. (2) APF has been significantly enhanced, which is mainly distributed in point clusters and strips in the farming and pastoral areas in northern Shaanxi to the Yanhe river basin. The high-value areas of ESF are clustered around the urbanized metropolitan circles and urban-rural staggered areas along the Great Wall. ECF is concentrated in areas with significant natural endowments and excellent ecological conditions. CRF is significantly higher in the municipal districts and the surrounding regional central cities. (3) There are noticeable differences in the gully agriculture regional function (GARF) evolution process due to the geographical environment and socio-economic development stages. In this regard, natural factors have tremendously affected APF, ESF, and ECF, while socio-economic factors greatly differ in the four functions. There are still differences in the driving mechanisms of modern gully agriculture evolution types; hence many critical policies in the Loess Plateau can directly affect the function evolution paths. The dynamic evolution of GARF can reflect the general law of rural human-earth system transition in gully areas, thereby providing policy ideas for high-quality development of agriculture in the Loess Plateau.

Urban construction land has relatively high human activity and high carbon emissions. Research on urban construction land prediction under carbon peak and neutrality goals (hereafter “dual carbon” goals) is important for territorial spatial planning. This study analyzed quantitative relationships between carbon emissions and urban construction land, and then modified the construction land demand prediction model. Thereafter, an integrated model for urban construction land demand prediction and spatial pattern simulation under “dual carbon” goals was developed, where urban construction land suitability was modified based on carbon source and sink capacity of different land-use types. Using Guangzhou as a case study, the integrated model was validated and applied to simulate the spatiotemporal dynamics of its urban construction land during 2030-2060 under baseline development and “dual carbon” goals scenarios. The simulation results showed that Guangzhou’s urban construction land expanded rapidly until 2030, with the spatial pattern not showing an intensive development trend. Guangzhou’s urban construction land expansion slowed during 2030-2060, with an average annual growth rate of 0.2%, and a centralized spatial pattern trend. Under the “dual carbon” goal scenario, Guangzhou’s urban construction land evolved into a polycentric development pattern in 2030. Compared with the baseline development scenario, urban construction land expansion in Guangzhou during 2030-2060 is slower, with an average annual growth rate of only 0.1%, and the polycentric development pattern of urban construction land was more prominent. Furthermore, land maintenance and growth, that is, a carbon sink, is more obvious under the “dual carbon” goals scenario, with the forest land area nearly 10.6% higher than that under the baseline development scenario. The study of urban construction land demand prediction and spatial pattern simulation under “dual carbon” goals provides a scientific decision-making support tool for territorial spatial planning, aiding in quantifying territorial spatial planning.

The 270 km long section of the Upper Yellow River at the First Great Bend is comprised of single channel and multiple channel systems that alternate among anastomosing, anabranching, meandering and braided reaches. The sequence of downstream pattern changes is characterized as: anastomosing-anabranching, anabranching-meandering, meandering-braided and braided-meandering. Remote sensing images, DEM data and field investigations are used to assess and interpret controls on these reach transitions. Channel slope and bed sediment size are key determinants of transitions in channel planform. Anastomosing reaches have a relatively high bed slope (0.86‰) and coarser sediment bed material (d₅₀ = 3.5 mm). In contrast, meandering reaches have a low slope (0.30‰) and fine sediment bed material (d₅₀ = 0.036 mm). The transition from a meandering to braided pattern is characterized by an increase in channel width-depth ratio, indicating the important role of bank strength (i.e. cohesive versus non-cohesive versus channel boundaries). Interestingly, the braided-meandering and meandering-braided transitions are coincident with variable flow inputs from tributary rivers (Baihe and Heihe rivers respectively). Theoretical analysis of the meandering-braided transition highlights the key control of channel width-depth ratio as a determinant of channel planform.

Ecological shelter zones reconstruction is an ecosystem restoration and conserva-tion project aimed to the ecological safety of nations, regions and basins. Reconstruction of ecological shelter zones of the upper reaches of the Yangtze River became one of the most important tasks of Western Development strategy. This article, taking Zhaotong as an exam-ple, studies the functional regionalization of ecological shelter zones. The study supplies a case for functional regionalization of small and medium regions whose main tasks are envi-ronment reservation. With the guidance of theories of functional regionalization, and based on the analysis of Zhaotong’s natural, ecological and socioeconomic factors, the paper suggests five principles for factors selection. These principles include: (1) reversing order evaluation; (2) selecting main factors; (3) keeping the integrality of administrative regions of towns; and (4) making the products acceptable by local government. To analyze spatial status of selected factors, LUCC data in 2002, 1:50,000 relief maps and town-unit socioeconomic statistical data in 2004 are used. RS and GIS tools are also applied to melt traditional and modern geo-graphical methods. This would be useful to functional regionalization research in mountain-ous areas. As a conclusion, the leading functional regions of ecological conservation or economic development are suggested, respectively. Zhaotong city is divided into two-level functional regions. The first-level includes three leading functional regions and they will lead developing direction of sub-regions. The second-level includes eight sub-regions, which are policy implemented regions, and will supply guidance to Zhaotong’s ecological shelter zones reconstruction.

This paper seeks to quantify the social and economic impact of resettlement based on the physiographic element changes post relocation. We focus on communities affected by the Nuozhadu hydropower project, the largest existing hydropower project on the mainstream of the Upper Mekong River. Soil and meteorological data were collected from the Soil Spatial Database and the China Terrestrial Ecological Information Spatial Meteorology Database, while social and economic data were collected via field surveys. We have three major conclusions: (1) Communities will be relocated to a new climate and new elevation, moving from a north tropical climate zone under 700 m to a subtropical climate zone above 700 m. (2) Physiographic element changes due to relocation will reduce household economic income. After relocation, the annual family income of the Shidaimao group decreased by 62%; the annual family income of the other 5 study groups (Lasa, Hani, Nochangchangyi, Mengsa, and Dawazi) dropped by 65%. (3) Communities relocated across the study township are 61.1% less connected with their former relatives after relocation while family-to-family free labor exchange, a previous community norm, decreased by 91%. China's dam resettlement compensation system focuses on the loss of economic resources after relocation. However, this study finds that the physiographic elements of the relocation sites are an important driver of ensuring economic growth and stability after relocation. As a result, we recommend more attention be paid to physiographic continuity when designing relocation models.

Climate change is likely to affect hydrological cycle through precipitation, evapotranspiration, soil moisture etc. In the present study, an attempt has been made to study the climate change and the sensitivity of estimated evapotranspiration to each climatic variable for a semi-arid region of Beijing in North China using data set from 1951 to 2010. Penman-Monteith method was used to calculate reference crop evapotranspiration (ETo). Changes of ETo to each climatic variable was estimated using a sensitivity analysis method proposed in this study. Results show that in the past 60 years, mean temperature and vapor pressure deficit (VPD) were significantly increasing, relative humidity and sunshine hours were significantly decreasing, and wind speed greatly oscillated without a significant trend. Total precipitation was significantly decreasing in corn season (from June to September), but it was increasing in wheat season (from October to next May). The change rates of temperature, relative humidity, VPD, wind speed, annual total precipitation, sunshine hours and solar radiation were 0.42℃, 1.47%, 0.04 kPa, 0.05 m·s^-1, 25.0 mm, 74.0 hours and 90.7 MJ·m^-2 per decade, respectively. In the past 60 years, yearly ETo was increasing with a rate of 19.5 mm per decade, and total ETos in wheat and corn seasons were increasing with rates of 13.1 and 5.3 mm per decade, respectively. Sensitivity analysis showed that mean air temperature was the first key factor for ETo change in the past 60 years, causing an annual total ETo increase of 7.4%, followed by relative humidity (5.5%) and sunshine hours (-3.1%); the less sensitivity factors were wind speed (0.7%), minimum temperature (-0.3%) and maximum temperature (-0.2%). A greater reduction of total ETo (12.3%) in the past 60 years was found in wheat season, mainly because of mean temperature (8.6%) and relative humidity (5.4%), as compared to a reduction of 6.0% in ETo during corn season due to sunshine hours (-6.9%), relative humidity (4.7%) and temperature (4.5%). Increasing precipitation in the wheat season will improve crop growth, while decreasing precipitation and increasing ETo in the corn season induces a great pressure for local government and farmers to use water more efficiently by widely adopting water-saving technologies in the future.

The estimation of surface evapotranspiration (ET) with satellite dataset is one of the main subjects in the understanding of climate change, disaster monitoring and the circulation of water vapor and energy in Tibet Autonomous Region (TAR). This research selects satellite images on January 11, April 6, July 31 and October 19 in 2010 as the representative of winter, spring, summer and autumn respectively, estimates the distribution of daily surface ET based on the surface energy balance system (SEBS) along with potential evapotranspiration (PET) and ET derived from Penman-Monteith (P-M) method. The results are obtained as follows. (1) The seasonal distribution of ET and PET basically decreases from the southeast part to the northwest part of TAR. Although ET and PET have similar spatial distributions, there are still some differences to estimate the extreme values especially the maximum value in the middle and southeastern parts of TAR. No matter what kind of methods we adopted, the maximum value of ET and PET always appears in summer, followed by autumn or spring while that in winter is the smallest. (2) In order to better understand the accuracy of SEBS model in the estimation of ET, we compared the ET from SEBS and the ET obtained from P-M method. Results show that the ET from SEBS could estimates the variation trend of actual ET, but it slightly underestimates or overestimates the value of ET as a whole, especially for those areas with thick forest. (3) The spatial distribution of Normalized Difference Vegetation Index (NDVI) exhibits a decreasing trend from the southeast part to the northwest part of TAR which displays remarkable consistency of distributions between ET and vegetation index. ET is well positively related to NDVI, minimum, mean, maximum air temperature and sunshine duration in different seasons while negatively related to precipitation, relative humidity and wind speed in summer.

Based on the analysis of suspended sediment elements at estuaries, influence of human activities and estuarine regulation projects on the turbidity maximum zone was studied according to the measurement data between 1959 and 2011. It was found that human activities had little effect on the seaward water while the sharp decrease of sediment volume and concentration in runoff led to the sharp decrease of turbidity maximum zone in the estuary. The concentration at outside sea and Hangzhou Bay did not change, and that along the Subei coast also decreased a little, which had no influence on the turbidity maximum zone. Compared with the concentration between 1959 and 1999, the peak of concentration moved upstream in the estuary, and the concentration in 2000-2009 decreased by about 24.73% with a narrower variation range along the river to the sea. The suspended sediment concentration in North Passage was low in upstream and downstream because of the decrease of seaward sediment and coarsening of bed material, while it was relatively high in the middle due to the influence of sediment cross the north jetty.

The water quality in the surface microlayer (SML) and subsurface water (SSW) in the Guangzhou segment of Pearl River, a eutrophic urban river section in China, were analyzed. The spatial and temporal dynamics of nutrient concentrations, heavy metals and bacteria were examined from two sampling sites in monthly samples throughout 2010. The mean concentrations of total nitrogen, ammonia, nitrate and nitrite were higher than 7.0 mg/L, 3.1 mg/L, 1.1 mg/L and 0.3 mg/L, while total phosphorus and orthophosphate were 0.5 mg/L and 0.1 mg/L, respectively. These results indicated that the water quality was rich in minerals and eutrophic. The mean concentrations of Mn and Fe were higher than 0.013 mg/L; and Ni, Cr and Pb were higher than 0.001 mg/L. The mean concentrations were in the order of Mn >Fe > Ni > Pb > Cr. The concentrations of heavy metals in the Guangzhou segment were lower than the limit of the surface water quality standards in China and the World Health Organization (WHO), but higher than the median values in the world’s freshwater. The density of bacteria ranged from 3.30×10⁵ to 5.23×10⁶ cells/mL, and the amount of cultivable heterotrophic bacteria ranged from 1.30×10³ to 1.89×10⁶ cfu/mL. Fecal coliform levels were beyond the V class of China water quality standard. The SML was enriched in nutrients, heavy metals and bacteria, with the maximum enrichment factor of 3.84 for nutrients, 8.00 for heavy metals, and 3.04 for bacteria, suggesting that the water quality of the SML of the Guangzhou segment of the Pearl River was more serious than in the SSW.

Based on long-term measurement data of weather/ecological stations over China, this paper calculated and produced annually- and seasonally-averaged Photosynthetically Active Radiation (PAR) spatial data from 1961 to 2007, using climatological calculations and spatialization techniques. The spatio-temporal variation characteristics of annually- and seasonally-averaged PAR spatial data over China in recent 50 years were analyzed with Mann-Kendall trend analysis method and GIS spatial analysis techniques. The results show that: (1) As a whole, the spatial distribution of PAR is complex and inhomogeneous across China, with lower PAR in the eastern and southern parts of China and higher PAR in the western part. Mean annual PAR over China ranges from 17.7 mol m^-2 d^-1 to 39.5 mol m^-2 d^-1. (2) Annually- and seasonally-averaged PAR of each pixel over China are averaged as a whole and the mean values decline visibly with fluctuant processes, and the changing rate of annually-averaged PAR is –0.138 mol m^-2 d^-1/10a. The changing amplitudes among four seasons are different, with maximum dropping in summer, and the descending speed of PAR is faster before the 1990s, after which the speed slows down. (3) The analysis by each pixel shows that PAR declines significantly (α=0.05) in most parts of China. Summer and winter play more important roles in the interannual variability of PAR. North China is always a decreasing zone in four seasons, while the northwest of Qinghai-Tibet Plateau turns to be an increasing zone in four seasons. (4) The spatial distributions of the interannual variability of PAR vary among different periods. The interannual variabilities of PAR in a certain region are different not only among four seasons, but also among different periods.

This paper presents a scenario-based assessment of global future food security. To do that, the socio-economic and climate change scenarios were defined for the future and were linked to an integrated modeling framework. The crop yields simulated by the GIS-based Environmental Policy Integrated Climate (EPIC) model and crop areas simulated by the crop choice decision model were combined to calculate the total food production and per capita food availability, which was used to represent the status of food availability and stability. The per capita Gross Domestic Product (GDP) simulated by IFPSIM model was used to reflect the situation of food accessibility and affordability. Based on these two indicators, the future food security status was assessed at a global scale over a period of approximately 20 years, starting from the year 2000. The results show that certain regions such as South Asia and most African countries will likely remain hotspots of food insecurity in the future as both the per capita food availability and the capacity of being able to import food will decrease between 2000 and 2020. Low food production associated with poverty is the determining factor to starvation in these regions, and more efforts are needed to combat hunger in terms of future actions. Other regions such as China, most Eastern European countries and most South American countries where there is an increase in per capita food availability or an increase in the capacity to import food between 2000 and 2020 might be able to improve their food security situation.

This paper calculated spatial accessibility of all counties (city, urban district) in China with cost weighted distance method. Region divisions of county accessibility were conducted, and relation of traffic accessibility and population aggregation was discussed in this paper. The results indicated that county accessibility in China had mainly low values and a distribution structure of circle layer and reverse-to-natural gradient. There was an obvious correlation between county accessibility and population density in China. With these analyses, inner mechanisms of population migration in different traffic conditions and region types were revealed, and can provide useful proposals to regional planning, traffic planning and smart distribution of people in China.

Whether economic agglomeration can promote improvement in environmental quality is of great importance not only to China’s pollution prevention and control plans but also to its future sustainable development. Based on the COD (Chemical Oxygen Demand) and NH₃-N (Ammonia Nitrogen) emissions Database of 339 Cities at the city level in China, this study explores the impact of economic agglomeration on water pollutant emissions, including the differences in magnitude of the impact in relation to city size using an econometric model. The study also examines the spillover effect of economic agglomeration, by conducting univariate and bivariate spatial autocorrelation analysis. The results show that economic agglomeration can effectively reduce water pollutant emissions, and a 1% increase in economic agglomeration could lead to a decrease in COD emissions by 0.117% and NH₃-N emissions by 0.102%. Compared with large and megacities, economic agglomeration has a more prominent effect on the emission reduction of water pollution in small- and medium-sized cities. From the perspective of spatial spillover, the interaction between economic agglomeration and water pollutant emissions shows four basic patterns: high agglomeration-high emissions, high agglomeration-low emissions, low agglomeration-high emissions, and low agglomeration-low emissions. The results suggest that the high agglomeration-high emissions regions are mainly distributed in the Beijing-Tianjin-Hebei region, Shandong Peninsula, and the Harbin-Changchun urban agglomeration; thus, local governments should consider the spatial spillover effect of economic agglomeration in formulating appropriate water pollutant mitigation policies.

Extraction and analysis of the shoreline and land reclamation patterns are important for studies on topics such as the dynamics of coastal wetland ecological environments, transportation and exchange of material energy in coastal regions, and recruitment of fishery resources. Spatial-temporal variations in the shoreline and land reclamation in the Bohai Sea were analyzed based on 49 Landsat images of 7 periods from 1985 to 2015. The following conclusions were drawn. (1) The extracted shoreline data based on visual interpretation had high precision, and the shoreline extraction errors could be controlled within the theoretical range. (2) Over the past 30 years, the shoreline of the Bohai Sea has exhibited an average rate of change of 188.47 m/a and an average accretion distance of 3.55×10 ³ m toward the sea. The fastest rate of shoreline change occurred in Laizhou Bay (134.78 m/a), followed by Bohai Bay (128.20 m/a) and Liaodong Bay (61.69 m/a). (3) The average rate of reclamation was 3.25×10 ⁴ ha/a in the Bohai Sea, where the total area of aquaculture land, unused land, and salt land exceeded 60% of the total reclamation area. (4) The geometric shape of the bay became increasingly complicated from year to year, and the geometric center of gravity of the bay moved rapidly toward the sea. In addition, the area of the bay showed a significant decreasing trend. Therefore, to protect the function and structure of the ecosystem in coastal regions, we must control the scale and rate of land reclamation in the future.

This paper investigated spatial structures of 3418 national protected areas (NPAs) grouped into 13 types using GIS and quantitative analysis, including point patterns, Ripley’s K function, hotspot clustering, quadrat analysis, and Gini coefficient. Spatial accessibility was calculated for all NPAs from matrix raster data using cost weighted distance on the ArcGIS platform. The results are as follows: (1) The NNI of NPAs is 0.515, Gini is 0.073, all of which indicates distribution was shown to be a spatially dependent agglomeration, and more balanced in the provinces. The national key parks and the national water conservancy scenic spots had present the strongest aggregation, with NNI of 0.563 and 0.561 respectively, and K index indicates reducing aggregation when distance exceeds 600 km. (2) The national forest parks account for the largest proportion of 22.87% of all NPAs, and the world biosphere reserves the least of 0.77%. The number of NPAs in Shandong with 240 had been the largest one in all the provinces, while Tianjin had the least number including 9 NPAs. (3) There is only one hot spot in the first-class zone, 5 in the second-class zones, and 51 in the third-class zones, which indicates NPAs are also aggregated at microscopic scales. (4) The hotspot NPA regions were mainly concentrated in the middle and lower reaches of the Yellow and Yangtze rivers, east of 100°E. High density of NPAs were generally in flat, water-rich, broad-leaved forest dominated plains and low mountain areas, with fertile soil, pleasant weather, long cultural history, and high transportation accessibility. (5) Average NPA accessible time is 60.05 min, with 70.76% regions being within 60 min, and the furthest was 777 min. The distribution of accessibility was positively related to the traffic lines. Interdepartmental protectionism has meant the various departments developed different management systems, standards, and technical specifications.

Functional zoning is a key step for the integrated planning and scientific management of a national park. Selecting the Three-River-Source National Park (TNP) as the study area, this paper establishes an evaluation system including 13 evaluation indexes which are classified into four categories, namely: ecosystem services; potential distribution of key species habitats; ecological sensitivity; and ecological resilience through the comprehensive analysis on the regional eco-environmental features in the study area. The results of the comprehensive analysis, combined with the functions and requirements of management of national parks, indicate that TNP is divided into the first-level zone (the core conservation area, the ecological restoration area and the traditional utilization area) with definite targets of space management and the second-level zone with implementation of control measures. This method of functional zoning lays a solid foundation for the scientific planning of TNP; moreover, our study provides new insights into other national parks’ functional zoning.

Knowledge of moisture sources is of great significance for understanding climatic change and landscape evolution in desert environments. In this paper, we aim to clarify moisture origins for the Alashan (Alxa) Sand Seas (ALSS) in western Inner Mongolia and their transport pathways during the Last Glacial Maximum (LGM) and the mid-Holocene using modern analogues and paleoclimatic simulations. Precipitation data for the period 1959-2015 from meteorological stations in the study area and wind and specific humidity data from the European Center for Medium-Range Weather Forecasts (ECMWF) daily reanalysis were adopted to determine the moisture sources of summer precipitation in the ALSS. In addition paleoclimate simulations under PMIP3/CMIP5 protocols were used to detect the atmospheric circulation and precipitation at 21 ka BP and 6 ka BP over the ALSS. We also reviewed paleoclimate records from the ALSS to acquire a semi-quantitative reconstruction of the moisture history during the late Pleistocene and Holocene. Our results suggest that the summer monsoon transported water vapor from the Indian Ocean and the South China Sea to the ALSS during July and August, causing increased precipitation. The dominant moisture source was from the southwest monsoon, while the East Asian summer monsoon also partly contributed to precipitation in the ALSS. The increased humidity during the period 8.2-4.2 ka BP in the ALSS, as derived from both climate simulation outputs and sedimentary records, was caused by monsoons according to the outputs of simulations. At 21 ka BP, the moisture sources of the ALSS were greatly associated with the prevailing westerlies.

Phenological modeling is not only important for the projection of future changes of certain phenophases but also crucial for systematically studying the spatiotemporal patterns of plant phenology. Based on ground phenological observations, we used two existing temperature-based models and 12 modified models with consideration of precipitation or soil moisture to simulate the bud-burst date (BBD) of four common herbaceous plants—Xanthium sibiricum, Plantago asiatica, Iris lactea and Taraxacum mongolicum—in temperate grasslands in Inner Mongolia. The results showed that (1) increase in temperature promoted the BBD of all species. However, effects of precipitation and soil moisture on BBD varied among species. (2) The modified models predicted the BBD of herbaceous plants with R ² ranging from 0.17 to 0.41 and RMSE ranging from 9.03 to 11.97 days, better than classical thermal models. (3) The spatiotemporal pattern of BBD during 1980-2015 showed that species with later BBD, e.g. X. sibiricum (mean: day of year 135.30) exhibited an evidently larger spatial difference in BBD (standard deviation: 13.88 days) than the other species. Our findings suggest that influences of temperature and water conditions need to be considered simultaneously in predicting the phenological response of herbaceous plants to climate change.

Climate change is a major driver of vegetation activity, and thus their complex processes become a frontier and difficulty in global change research. To understand this relationship between climate change and vegetation activity, the spatial distribution and dynamic characteristics of the response of NDVI to climate change were investigated by the geographically weighted regression (GWR) model during 1982 to 2013 in China. This model was run based on the combined datasets of satellite vegetation index (NDVI) and climate observation (temperature and moisture) from meteorological stations nationwide. The results showed that the spatial non-stationary relationship between NDVI and surface temperature has appeared in China: the significant negative temperature-vegetation relationship was located in Northeast, Northwest and Southeast China, while the positive correlation was more concentrated from southwest to northeast. By comparing the normalized regression coefficients from GWR model for different climate factors, it presented the regions with moisture dominants for NDVI were in North China and the Tibetan Plateau, and the areas of temperature dominants were distributed in East, Central and Southwest China, where the annual mean maximum temperature accounted for the largest areas. In addition, regression coefficients from GWR model between NDVI dynamics and climate variability indicated that the higher warming rate could result in the weakened vegetation activity through some mechanisms such as enhanced drought, while the moisture variability could mediate the hydrothermal conditions for the variation of vegetation activity. When the increasing rate of photosynthesis exceeded that of respiration, the positive correlation between vegetation dynamics and climate variability was reflected. However, the continuous and dynamic process of vegetation activity response to climate change will be determined by spatially heterogeneous conditions in climate change and vegetation cover. Furthermore, the dynamic description of climate-induced vegetation activity from its rise to decline in different regions is expected to provide a scientific basis for initiating ecosystem-based adaptation strategies in response to global climate change.

A model integrating geo-information and self-organizing map (SOM) for exploring the database of soil environmental surveys was established. The dataset of 5 heavy metals (As, Cd, Cr, Hg, and Pb) was built by the regular grid sampling in Hechi, Guangxi Zhuang Autonomous Region in southern China. Auxiliary datasets were collected throughout the study area to help interpret the potential causes of pollution. The main findings are as follows: (1) Soil samples of 5 elements exhibited strong variation and high skewness. High pollution risk existed in the case study area, especially Hg and Cd. (2) As and Pb had a similar topological distribution pattern, meaning they behaved similarly in the soil environment. Cr had behaviours in soil different from those of the other 4 elements. (3) From the U-matrix of SOM networks, 3 levels of SEQ were identified, and 11 high risk areas of soil heavy metal-contaminated were found throughout the study area, which were basically near rivers, factories, and ore zones. (4) The variations of contamination index (CI) followed the trend of construction land (1.353) > forestland (1.267) > cropland (1.175) > grassland (1.056), which suggest that decision makers should focus more on the problem of soil pollution surrounding industrial and mining enterprises and farmland.

The goal of our work was to locate and quantify changes that occurred in 66% of the Mexican coastline, based on four land cover maps generated by the Mexican Mangrove Monitoring System (SMMM) of the National Commission for the Knowledge and Use of Biodiversity (CONABIO) for the years 1970/81, 2005, 2010, and 2015. Our results showed overall dominance of erosion over accretion processes, beaches being the most affected coastal land cover. Emphasis was placed on identification and description of coastline sites in which land was either continuously lost (erosion) or gained (accretion) during the studied time periods. These sites were defined as continuous unidirectional dynamic sites and were compared with previous knowledge about the geodynamics of Mexican coasts. Continuous unidirectional dynamic sites were distributed throughout the study area and within all land cover types, but predominantly corresponded to areas covered by mangroves in the states of Campeche and Nayarit. Finally, we found an intensification of coastal erosion-accretion processes over time; coastline change rates having duplicated between the earliest (1970/81-2005) and the two more recent (2005-2010, and 2010-2015) analysed time periods, with erosion rates for each corresponding period of -3 m/yr, -7.5 m/yr, and -7.3 m/yr, and accretion rates of 2.8 m/yr, 7.3 m/yr, and 6.9 m/yr, respectively.

Wind-driven soil erosion results in land degradation, desertification, atmospheric dust, and sandstorms. The Hunshandake Sandy Land, an important part of the Two Barriers and Three Belts project, plays important roles in preventing desert and sandy land expansion and in maintaining local sustainability. Hence, assessing soil erosion and soil accumulation moduli and analyzing the dynamic changes are valuable. In this paper, Zhenglan Banner, located on the southern margin of the Hunshandake Sandy Land, was selected as the study area. The soil erosion and accumulation moduli were estimated using the ¹³⁷Cs and ²¹⁰Pb_ex composite tracing technique, and the dynamics of soil erosion and soil accumulation were analyzed during two periods. The results are as follows: (1) the regional ¹³⁷Cs reference inventory was 2123.5±163.94 Bq/m ², and the regional ²¹⁰Pb_ex reference inventory was 8112±1787.62 Bq/m ². (2) Based on the ¹³⁷Cs isotope tracing analysis, the erosion moduli ranged from -483.99 to 740.31 t·km ^-2·a ^-1. Based on the ²¹⁰Pb_ex isotope tracing analysis, the erosion moduli ranged from -441.53 to 797.98 t·km ^-2·a ^-1. (3) Compared with the earliest 50 years, the subsequent 50 years exhibited lower soil erosion moduli and accumulation moduli. Therefore, the activities of local sand dunes weakened, and the quality of the local ecological environment improved. The multi-isotope composite tracing technique combining the tracers ¹³⁷Cs and ²¹⁰Pb_ex has potential for similar soil erosion studies in arid or semiarid regions around the world.

Geomorphic evolution often presents a spatial pattern of a “young to old” distribution under certain natural environmental conditions, whereby sampling the geomorphic types and characteristics in spatial sequence can provide evidence for the individual landform evolution and change. This so-called space-for-time substitution has been a methodology in geomorphologic research. This paper firstly introduced the basic concepts and background of the space-for-time substitution, then a full review has been conducted of recent research progress in geomorphic evolution based on the space-for-time substitution, such as fluvial landform, structural landform, estuarine landform and coastal landform. Finally, the basic principle of space-for-time substitution in geomorphology is developed. This review is intended to introduce the achievements of geomorphic evolution research using space-for-time substitution method and to point out the critical research needs to better understand and predict the geomorphic evolution in the future.

Urban agglomerations are formed when a country is in the advanced stages of industrialization and urbanization. They are highly integrated groups of cities that form and develop through a natural, gradual process as the relationship between them changes from one of competition to assimilation following law of natural development. China is currently in a new stage of transitional development characterized by its New-Type Urbanization Plan. It has entered a new era in which it is a global leader in urban agglomeration development, and China’s research and development models are being imitated and adopted by countries around the world. This paper adopts a theoretical approach to propose the basic law governing the formation, development and expansion of urban agglomerations. This includes the stage-based formation and development law, multi-scale intensive-use transmission law, crystal-structure spatial composition law, egg-shaped expansion evolution law, “saplings-to-forest” natural growth law, and sustainable development incremental increase law. Guided by these law, China has created a hierarchical organizational configuration for optimizing the spatial structure of its urban agglomerations. It has also formulated urban agglomeration development plans and proposed research-based measures to resolve problems specific to urban agglomerations and to promote their sustainable development. The law governing the formation, development and expansion of urban agglomerations play an important role in guiding their development in China and will play a greater role in the future.

The cultivation of mountainous land results in water loss and soil erosion. With rapid urbanization and industrialization in China, labor emigration relieves the cultivation of mountainous areas in regions with high poverty and leads to a significant land use transition. This research built an analysis framework for “land use transition - driving mechanism - effects - responses” for mountainous areas of China undergoing land use transition and then proposed the direction of mountainous land consolidation. The results showed that the turning point of land use morphology was the core of rural land use transition in mountainous areas. The expansion of cropland and the contraction of forestland have transitioned to the abandonment of cropland and the expansion of forestland; this transition was the main characteristic of the dominant land use change. Land marginalization and land ecological functional recovery were the main characteristics of the recessive land use transition in mountainous areas. Socioeconomic factors were the primary driving forces during land use transition in mountainous areas, with labor emigration being the most direct force. The rising costs of farming and the challenging living conditions causing labor emigration were fundamental driving forces. Rural land use transition in mountainous areas reduced the vulnerability of the ecological function of land ecosystems. The advantages and disadvantages of the socioeconomic effects should focus on rural development of mountainous areas as well as the livelihood of farmers; this should be further supported by empirical and quantitative research. Rural land use transition of mountainous areas improves natural restoration and is related to socioeconomic development. Rural land consolidation of mountainous areas should conform to land use transition, with the goal of shifting from the increase of cultivated land to the synergies of ecological and environmental protection.

This paper reviews the process of transportation construction in China and investigates the developmental and spatial characteristics of transportation patterns. The principles of transportation evolution including stages, structures and orders are systematically analyzed. The investigation shows that China’s transportation construction mode has upgraded from investment-driven scale expansion to quality improvement driven by efficiency and promotion. The rapid growth and development of transportation networks has significantly influenced economic and social activities in time and space. The resulting spatial convergence and dominance have improved distribution, promoting development of the socioeconomic structure. Regional development that has traditionally been based on corridors has changed into a networked mode centered on cities and metropolitan areas. The transportation pattern follows evolutionary principles. China has been moving from a hierarchical structure to a cascade structure. Simultaneously, the socioeconomic pattern has changed from an axis to a hub-and-spoke structure with a preliminary ordered network. As transportation networks grow, China’s functional spatial structure and ordered network will gradually become stabilized and balanced.

Geomorphologic maps are one of the most fundamental materials of the natural environment. They have been widely used in scientific research, resource exploration and extraction, education and military affairs etc. An editorial committee was established in 2001 to collect materials for researching and compiling a set of new 1:1,000,000 geomorphologic atlas of China. A digital geomorphologic database was created with visual interpretation from Landsat TM/ETM imageries and SRTM-DEM etc. The atlas compiled from the database was finished. The main characteristics of the atlas are as follows: Firstly, Landsat TM/ETM imageries, published geomorphologic maps or sketches, geographical base maps, digital geological maps, and other thematic maps were collected, which were uniformly geometrically rectified, clipped into uniform sheets, and stored in the foundation database. Secondly, based on the legends of 15 sheets 1:1,000,000 maps published in the 1980s, a geomorphologic classification system was built by combining morphology and genesis types. The system comprised seven hierarchical layers: basic morphology, genesis, sub-genesis, morphology, micro-morphology, slope and aspect, material composition and lithology. These layers were stored in the database during visual image interpretation. About 2000 kinds of morpho- genesis and 300 kinds of morpho-structure were interpreted. Thirdly, the legend system was built, which included color, symbol bases and note bases etc., compilation standards and procedures were developed, 74 sheets of 1:1,000,000 covering all land and sea territories of China were compiled, the 1:1,000,000 geomorphologic atlas of the People’s Republic of China was finished and published. The atlas will fill the blanks in national basic scale thematic maps, and the geomorphologic database could be applied widely in many fields in the future.