The objective of this study is to quantitatively evaluate Tropical Rainfall Measuring Mission (TRMM) data with rain gauge data and further to use this TRMM data to drive a Distributed Time-Variant Gain Model (DTVGM) to perform hydrological simulations in the semi-humid Weihe River catchment in China. Before the simulations, a comparison with a 10-year (2001-2010) daily rain gauge data set reveals that, at daily time step, TRMM rainfall data are better at capturing rain occurrence and mean values than rainfall extremes. On a monthly time scale, good linear relationships between TRMM and rain gauge rainfall data are found, with determination coefficients R² varying between 0.78 and 0.89 for the individual stations. Subsequent simulation results of seven years (2001-2007) of data on daily hydrological processes confirm that the DTVGM when calibrated by rain gauge data performs better than when calibrated by TRMM data, but the performance of the simulation driven by TRMM data is better than that driven by gauge data on a monthly time scale. The results thus suggest that TRMM rainfall data are more suitable for monthly streamflow simulation in the study area, and that, when the effects of recalibration and the results for water balance components are also taken into account, the TRMM 3B42-V7 product has the potential to perform well in similar basins.

Urban expansion models are useful tools to understand urbanization process and have been given much attention. However, urban expansion is a complicated socio-economic phenomenon that is affected by complex and volatile factors involving in great uncertainties. Therefore, the accurate simulation of the urban expansion process remains challenging. In this paper, we make an attempt to solve such uncertainty through a reversal process and view urban expansion as a process wherein the urban landscape overcomes resistance from other landscapes. We developed an innovative approach derived from the minimum cumulative resistance (MCR) model that involved the introduction of a relative resistance factor for different source levels and the consideration of rigid constraints on urban expansion caused by ecological barriers. Using this approach, the urban expansion ecological resistance (UEER) model was created to describe ecological resistance surfaces suitable for simulating urban expansion and used to simulate urban expansion in Guangzhou. The study results demonstrate that the ecological resistance surface generated by the UEER model comprehensively reflects ecological resistance to urban expansion and indicates the spatial trends in urban expansion. The simulation results from the UEER-based model were more realistic and more accurately reflected ecological protection requirements than the conventional MCR-based model. These findings can enhance urban expansion simulation methods.

China has witnessed unprecedented urbanization over the past decades. The rapid expansion of urban population has been dominantly contributed by the floating population from rural areas, of which the spatiotemporal patterns, driving forces, and multidimensional effects are scrutinized and evaluated in this study by using the latest national censuses conducted in 2000 and 2010. Analysis based on the county-level data comes to conclusions as follows. The spatial pattern of floating population has remained stable over the first decade of the new century. The top 1% cities with the largest floating population received 45.5% of all migrants in China. As the rapid development of mega-city regions, the coastal concentration areas of floating population tended to geographically united as a whole, whereas the spatial distribution of migrants within each region varied significantly. The migrant concentration area in the Yangtze River Delta was the largest and its expansion was also the most salient. However, the floating population has growingly moved into provincial capitals and other big cities in the inland regions and its gravity center has moved northward for around 110 km during the study period. The spatial pattern of floating population has been formed jointly by the state and market forces in transitional China and the impacts of state forces have been surpassed by those of market forces in the country as a whole. The attractiveness of coastal cities and counties to the floating population comes mainly from the nonagricultural employment opportunities and public services, reflecting that long-distance and long-term migrants have moved coastward not only to gain employment but also to enjoy city life. By contrast, in the central and western regions, places with a higher economic development level and at a higher administrative level are more attractive to floating populations, demonstrating that the state remains to play an important role in allocating economic resources and promoting regional development in inland China. As the main body of new urban residents, the floating population has contributed substantially to the elevation of the urbanization levels of migrant-sending and -receiving places, by 20.0% and 49.5% respectively. Compared with extensively investigated interprovincial migrants, intra-provincial migrants have higher intention and ability to permanently live in cities and thus might become the main force of China’s urbanization in the coming decades. The internal migration has also reshaped China’s urban system in terms of its hierarchical organization and spatial structure.

In this study, we analyzed the spatiotemporal variation of cold surges in Inner Mongolia between 1960 and 2012 and their possible driving factors using daily minimum temperature data from 121 meteorological stations in Inner Mongolia and the surrounding areas. These data were analyzed utilizing a piecewise regression model, a Sen+Mann- Kendall model, and a correlation analysis. Results demonstrated that (1) the frequency of single-station cold surges decreased in Inner Mongolia during the study period, with a linear tendency of -0.5 times/10a (-2.4 to 1.2 times/10a). Prior to 1991, a significant decreasing trend of -1.1 times/10a (-3.3 to 2.5 times/10a) was detected, while an increasing trend of 0.45 times/10a (-4.4 to 4.2 times/10a) was found after 1991. On a seasonal scale, the trend in spring cold surges was consistent with annual values, and the most obvious change in cold surges occurred during spring. Monthly cold surge frequency displayed a bimodal structure, and November witnessed the highest incidence of cold surge. (2) Spatially, the high incidence of cold surge is mainly observed in the northern and central parts of Inner Mongolia, with a higher occurrence observed in the northern than in the central part. Inter-decadal characteristic also revealed that high frequency and low frequency regions presented decreasing and increasing trends, respectively, between 1960 and 1990. High frequency regions expanded after the 1990s, and regions exhibiting high cold surge frequency were mainly distributed in Tulihe, Xiao’ergou, and Xi Ujimqin Banner. (3) On an annual scale, the cold surge was dominated by AO, NAO, CA, APVII, and CQ. However, seasonal differences in the driving forces of cold surges were detected. Winter cold surges were significantly correlated with AO, NAO, SHI, CA, TPI, APVII, CW, and IZ, indicating they were caused by multiple factors. Autumn cold surges were mainly affected by CA and IM, while spring cold surges were significantly correlated with CA and APVII.

Seasonal water-level fluctuations (WLF) play a dominate role in lacustrine ecosystems. River-lake interaction is a direct factor in changes of seasonal lake WLF, especially for those lakes naturally connected to upstream and downstream rivers. During the past decade, the modification of WLF in the Poyang Lake (the largest freshwater lake in China) has caused intensified flood and irrigation crises, reduced water availability, compromised water quality and extensive degradation of the lake ecosystem. There has been a conjecture as to whether the modification was caused by its interactions with Yangtze River. In this study, we investigated the variations of seasonal WLF in China’s Poyang Lake by comparing the water levels during the four distinct seasons (the dry season, the rising season, the flood season, and the retreating season) before and after 2003 when the Three Gorge Dam operated. The Water Surface Slope (WSS) was used as a representative parameter to measure the changes in river-lake interaction and its impacts on seasonal WLF. The results showed that the magnitude of seasonal WLF has changed considerably since 2003; the seasonal WLF of the Poyang Lake have been significantly altered by the fact that the water levels both rise and retreat earlier in the season and lowered water levels in general. The fluctuations of river-lake interactions, in particular the changes during the retreating season, are mainly responsible for these variations in magnitude of seasonal WLF. This study demonstrates that WSS is a representative parameter to denote river-lake interactions, and the results indicate that more emphasis should be placed on the decrease of the Poyang Lake caused by the lowered water levels of the Yangtze River, especially in the retreating season.

Detecting variation trend in dry-wet conditions can provide information for developing strategic measures to mitigate the impacts of global warming, particularly in dry regions. Taking the hilly region of northern Shaanxi on the Loess Plateau as a case area, this study analyzed the trend of aridity variation during 1981-2012, and explored the effect of vegetation restoration promoted by the Grain-for-Green (GFG) program implemented in 1999. The results indicated that the aridity in the region was non-significantly increased by 0.88% per year during 1981-2012, showing a drying trend. This drying trend and amplitude were changed by the influence of vegetation restoration promoted by the GFG program, based on two findings. The first one was that the aridity variation tended to increase during 1981-1999 while it turned to decrease during 2000-2012, with the regional mean relative change rate changed from 2.45% to -1.06%. This distinction was more remarkable in the loess gully region, where the vegetation was improved more obviously. The second one was that the mean vegetation coverage as indicated by EVI increased by 0.90% to 4.32% per year at county level, while the aridity decreased by 0.14% to 2.32% per year during 2000-2012. The regression analysis using the mean county data indicated that the change rate of aridity was negatively related to that of EVI with the coefficient of determination (R²) of 0.56, illustrating that around half of the aridity decline was explained by the EVI change. The mechanism of this effect was complicated, but it was found that the wind speed decline induced by the vegetation improvement could be an important contributor. It is concluded that the region became drier during 1981-2012, but the eco-restoration reduced the drying speed. However, this conclusion is involved in uncertainties, and further study based on experiments is needed to confirm the effect of the GFG-promoted vegetation restoration.

According to the highway data and some socioeconomic data of 1990, 1994, 2000, 2005 and 2009 of county units in the Pearl River Delta, this paper measured urban integrated power of different counties in different years by factor analysis, and estimated each county’s potential in each year by means of expanded potential model. Based on that, the spatio-temporal association patterns and evolution of county potential were analyzed using spatio-temporal autocorrelation methods, and the validity of spatio-temporal association patterns was verified by comparing with spatial association patterns and cross-correlation function. The main results are shown as follows: (1) The global spatio-temporal association of county potential showed a positive effect during the study period. But this positive effect was not strong, and it had been slowly strengthened during 1994-2005 and decayed during 2005-2009. The local spatio-temporal association characteristics of most counties’ potential kept relatively stable and focused on a positive autocorrelation, however, there were obvious transformations in some counties among four types of local spatio-temporal association (i.e., HH, LL, HL and LH). (2) The distribution difference and its change of local spatio-temporal association types of county potential were obvious. Spatio-temporal HH type units were located in the central zone and Shenzhen-Dongguan region of the eastern zone, but the central spatio-temporal HH area shrunk to the Guangzhou-Foshan core metropolitan region only after 2000; the spatio-temporal LL area in the western zone kept relatively stable with a surface-shaped continuous distribution pattern, new LL type units emerged in the south-central zone since 2005, the eastern LL area expanded during 1994-2000, but then gradually shrunk and scattered at the eastern edge in 2009; the spatio-temporal HL and LH areas varied significantly. (3) The local spatio-temporal association patterns of county potential among the three zones presented significant disparity, and obvious difference between the eastern and central zones tended to decrease, whereas that between the western zone and the central and eastern zones further expanded. (4) Spatio-temporal autocorrelation methods can efficiently mine the spatio-temporal association patterns of county potential, and can better reveal the complicated spatio-temporal interaction between counties than ESDA methods.

A network perspective has increasingly become an organizational paradigm for understanding regional spatial structures. Based on a critical overview of existing empirical models for estimating intercity networks based on firm linkages, this study extends the recently proposed regional corporate city model algorithm by proposing a new method for approximating urban networks based on the locational strategies of firms. The new method considers both regional and hierarchical network features and avoids the information loss associated with the conversion from two-mode firm-city networks to one-mode city-city networks. In addition, networks estimated by using the method proposed herein are suitable when employing social network analysis. Finally, this method is empirically validated by examining intercity firm networks formed by advanced producer services firms in China’s two largest metropolitan areas, namely the Yangtze River Delta and Pearl River Delta. The presented empirical analysis suggests two main findings. First, in contrast to conventional methods (e.g., the interlocking city network model), our new method produces regional and hierarchical urban networks that more closely resemble reality. Second, the new method allows us to use social network analysis to assess betweenness and closeness centralities. However, regardless of the model applied, the validity of any method that measures urban networks depends on the soundness of its underlying assumptions about how network actors (firms, in our case) interact.

The sediment discharge from the Yangtze River Basin has a stepwise decreasing trend in recent years. The impounding of the Three Gorges Reservoir exacerbated this decreasing trend and affected the change of the suspended sediment concentration (SSC) in the Yangtze River Estuary through the transmission effect. The SSC data of the Yangtze River Estuary during 1959-2012 showed that: (1) The SSC in the South Branch of the Yangtze River in the estuary and in the off-shore sea area displayed decreasing trends and decreased less towards the sea. At the same time, the difference in decreasing magnitude between SSC and sediment discharge became bigger towards the sea. (2) For the North Branch the preferential flow did not change much but the SSC tended to decrease, which was mainly caused by the decrease of SSC in the South Branch and China East Sea. (3) Due to the decreased runoff and the relatively strengthened tide, the peak area of the SSC in the bar shoal section in 2003-2012 moved inward for about 1/6 longitude unit compared with that in 1984-2002, and the inward-moving distance was in the order of flood season > annual average > dry season. (4) In the inlet of the South Passage, the SSC decreased mainly because the increase caused by resuspension and shore-groove exchange was less than the decrease caused by the sharp SSC decrease in the basin and the sea areas. The reverse was true in the middle section, where the SSC showed an increasing trend. (5) In the inlet of the North Passage, under the combined influence of decreased flow split and sediment split ratios, the decreased SSC in the basin and the sea area and decreased amount of resuspension, the SSC displayed a decreasing trend. In the middle section, because the increased amount caused by sediment going over the dyke was markedly more than the decreased amount caused by external environments, the SSC tended to increase. Holistically, the sharp decrease in sediment discharge caused synchronized SSC decreases in the Yangtze River Estuary. But there were still areas, where the SSC displayed increasing trends, indicating synchronicity and difference in the response of SSC to the sharp decrease in sediment discharge from the basin.

Evaluating the effectiveness of protecting nature assets is a vital component of responsive, pro-active management of protected areas. It is important to protect reserves of geological (including fossils) assets as a means to also protect national and natural heritage. At the end of 2013, 2669 protected areas had been established in China and 123 of them are reserves for nature assets. This paper builds an evaluation framework for protection effectiveness of these assets. The current elements and characteristics for effective protection are analyzed, along with an analysis of existing problems so as to construct a scientific approach to protect these assets. The influencing elements and characteristics for effective protection of nature asset reserves are included in an index evaluation system for effective protection in such areas, which contains four parts-target layer, evaluation criteria, evaluation indexes, and evaluation parameters-based on related documents and files. For the target layer, it includes nature asset evaluation and management evaluation. In the end, it is discussed how to build a comprehensive evaluation model and achieve an effective quantitative evaluation.

Depended on the analysis of ground snow situation, soil moisture loss speed and soil structure after planting crops of Mu Us Sandy Land remedied with feldspathic sandstone in the fallow period, it is concluded that feldspathic sandstone mixed with sand improved the sand stabilization in the governance of Mu Us Sandy Land in the fallow period. The sandy land remedied with feldspathic sandstone had big snow coverage, 25%-75% higher than normal sand; soil moisture losses slowed down, and moisture content rose by over 3 times; soil structure had been improved, and water stable aggregate content increased by 6.52%-18.04%; survival rate of protection forest increased to 85%; and ground flatness is less than 1%. The above conditions weakened sand rising conditions of Mu Us Sandy Land in the fallow period and formed two protective layers of snow cover and soil frozen layer under cold weather so as to prevent against wind erosion.

Before the emergence of modern modes of transport, the traditional road infrastructure was the major historical means of carrying out nationwide socio-economic exchange. However, the history of transport infrastructure has received little attention from researchers. Given this background, the work reported here examined the long-term development of transport networks in China. The national road network was selected for study and the 3500 years from 1600 BC to 1900 AD was chosen as the study period. Indicators were designed for the maturity level of road networks and an accessibility model was developed for the paths of the shortest distance. The evolution of the road network in China since the Shang Dynasty (1600 BC) was described and its major features were summarized to reveal long-term regularities. The maturity level of the road network and its accessibility was assessed and regions with good and poor networks were identified. The relationship between China’s natural, social, and economic systems and the road network were discussed. Our analysis shows that the road network in China has a number of long-term regularities. The continuously expanding road network follows a path of inland expansion especially towards the border areas. However, its coverage and accessibility are characterized by a core-peripheral configuration, which has close relationships with, not only the natural conditions, but also national defense and warfare. The centralization of national power, national land governance, postal transport, the transport of specialized cargos, and international trade are also related to the development of the road network. This research draws attention to the evolving regularities of transport networks.

Rural tourism has become an important driving force of rural urbanization in China. As the main reception base and important tourism attraction, tourism village is the core element of the tourism destination system. Integrating the method of PRA (Participatory Rural Assessment), GIS technology and high-resolution remote sensing images, this study aims to analyze the spatial morphology evolution of rural settlements induced by tourism through a comparative study of three tourism villages in Yesanpo tourism area. The results suggest the emergence of a “core-periphery” pattern of the spatial evolution of rural settlements. The closer to the core scenic spot, the higher degree of land-use intensity the village shows, as well as the more mature tourism function and greater change in landscape pattern. In particular, Gougezhuang shows an increase of the floor area ratio from 0.17 to 0.44, with the most mature tourism function and the lowest authenticity index of 0.448. Liujiahe has gone through the largest increase in construction land area from 17.3564 ha to 34.1128 ha, with moderately mature tourism function and relatively stable authenticity index of 0.566. Shangzhuang has the lowest construction land scale and intensity, with the poorest tourism function and most well-preserved landscape authenticity index of 0.942. Overall, in terms of the spatial morphology, the three villages show the characteristics of “modern town”, “semi-urbanization” and “traditional village” respectively, in corresponding to three land development types: “intensive reconstruction type”, “enclave extension type” and “in situ utilization type”. The spatial evolution patterns of these three villages imply the spatial characteristics of the touristization of traditional villages in different stages, and also have great representative value for the management of rural settlements in tourism areas in China.

Urban agglomerations are an inevitable outcome of China’s new national industrialization and urbanization reaching relatively advanced stages of development over the past 30 years. In the early 2000s, urban agglomerations became new geographical units for participating in global competition and the international division of labor, and China has spent the past decade promoting them as the main spaces for pushing forward its new form of urbanization. The convening of the first Central Work Conference on Urbanization and the National New-type Urbanization Plan (2014-2020) further defined the status of urban agglomerations as the main players in promoting China’s new type of national urbanization. Nevertheless, urban agglomerations remain a weak link in Chinese academia and are in urgent need of study. Only 19 articles on the theme of urban agglomerations were published in the journal Acta Geographica Sinica between 1934 and 2013, accounting for only 0.55% of all articles written during that period. Not only are there very few, they have also all been published within a relatively short period of time, with the first having been published only 10 years ago. The studies are also concentrated among only a few authors and institutions, and research is aimed at national requirements but is rather divergent. Even so, some studies on urban agglomerations have played a leading role and made important contributions to dictating the overall formation of urban agglomerations nationwide. Specifically, a proposed spatial pattern for urban agglomerations formed the basic framework for the spatial structure of China’s urban agglomerations and guided the government to make urban agglomerations the main urban pattern when promoting the new type of urbanization; proposed standards and technologies for identifying the spatial dimensions of urban agglomerations played an important role in defining the scope of national urban agglomerations; a series of studies in the area of urban agglomerations spurred more in-depth and practical studies in the field; and studies on issues related to the formation and growth of urban agglomerations provided warnings on the future selection and development of urban agglomerations. Taking the progress and results of these studies as a foundation, the foci of selecting and developing urban agglomerations in China are as follows: to be problem-oriented and profoundly reflect on and review new problems exposed in the selection and development of urban agglomerations; to concentrate on urban agglomerations and lay importance on the formation of a new “5+9+6” spatial structure for China’s urban agglomerations; to rely on urban agglomerations and promote the formation of a new pattern of national urbanization along the main axes highlighted by urban agglomerations; to be guided by national strategic demand and continue to deepen understanding of major scientific issues in the course of the formation and development of urban agglomerations, including studying the resource and environmental effects of high-density urban agglomerations, scientifically examining resource and environmental carrying capacities of high-density urban agglomerations, creating new management systems and government coordination mechanisms for the formation and development of urban agglomerations, studying the establishment of public finance systems and public finance reserve mechanisms for urban agglomerations, and studying and formulating technical specifications for urban agglomeration planning and standards for delineating urban agglomeration boundaries.

The Yangtze delta’s response to accelerating river damming and irrigation is a topic of global concern. This research analyzed the general erosion-accretion of the submerged delta front, the spatio-temporal changing pattern in different sub-regions, the geomorphological changes in typical cross-sections, and the geomorphological causes of the four main sub-regions (the eastern tidal wetland of Chongming-CM, the Hengsha shoal-HS, the Jiuduansha wetland-JDS, and the eastern tidal wetland of Nanhui-NH). Data sources include topographic data measured at high-resolution, sediment load at Datong Station, and the corresponding estuary construction information. Major findings are: (1) in general, the study area had slightly eroded (the erosion area ratio was 51.83% and the accretion area ratio was 48.17%) from 1982 to 2010, and it had experienced a shift of “erosion-accretion- erosion”. The spatio-temporal change of geomorphology was also significant in the eight sub-regions, excluding constant erosion in the North Channel; (2) evolution in eastern and northern CM and HS, northern JDS, and the region within the 5 m isobath of NH was dominated by vertical deposition, which was the opposite of that in southern CM and HS, and the region within the 5 m isobath of eastern and southern JDS; (3) on the whole, the encompassed surface areas (ESAs) of the 2 m and 5 m isobaths kept increasing, and the annual growth rates reached 10.42 km²/yr and 7.99 km²/yr respectively during 1982-2010 (however, four sub-regions exhibited disagreements), and in the whole region and all sub-regions, the ESA of the 10 m isobath decreased, while the ESA of the 15 m isobath changed slightly during the period and remained stable; (4) being less influenced by the estuarine engineering, CM was the only sub-region where the ESA of the isobath decreased in accordance with the decline of the sediment load. Major conclusions are that estuarine engineering projects play an increasingly important role in affecting the submerged delta against the macro-background of the reduction of sediment load, the change of ESA and the distribution of isobaths. Along with the accelerating construction of the Shanghai International Shipping Centre and reclamation project, the geomorphological evolution of the submerged delta will become more complex and thus deserves frequent monitoring in the future.

Based on field-survey hydrological series in the Dongting Lake watershed from 1951 to 2011, the variations of lakebed sediment siltation/erosion (S/E) regimes of the Dongting Lake after the operation of the Three Gorges Reservoir (TGR) were analyzed. Significantly positive correlations were found between the flow rate from Zhicheng and the Three Outlets (r²=0.859, p<0.0001), and between the flow rate and sediment delivery rate at the Three Outlets (r²=0.895, p<0.0001). This indicated that the flow rate and sediment delivery rate at the Three Outlets were largely determined by the flow rate from the upstream Yangtze River. Sediment deposition amount in the Dongting Lake basin dropped from +4796.4×10⁴ t during the period before the operation of TGR (1999-2002) to +684.1×10⁴ t, +449.8×10⁴ t and -559.6×10⁴ t during the impoundment Phases I, II and III of TGR. The S/E regimes changed from a siltation-dominant to an erosion-dominant state under the pre-discharge, water-storage and water-supplement dispatch over the impoundment from Phase I to III. The sediment deposition amount decreased dramatically under the flood-storage dispatch over the impoundment Phase I to III. The estimated annual mean flow rate, sediment delivery rate and sediment concentration thresholds were respectively 970.81 m³/s, 466.82 kg/s and 0.481 kg/m³ for the upstream Three Outlets to maintain an erosion-dominant state in the downstream linked the Dongting Lake.

The impact of reservoirs on downstream river channel change has been a scientific issue in fluvial geomorphology during the last few decades. However, it is still a difficult issue as to how to express quantitatively the channel adjustment in the Inner Mongolian reach of the Yellow River induced by the joint operation of upstream reservoirs. Based on the shape parameters of channel cross-sections at four gauging stations in this river reach over a flooding season in two periods, 1978-1982 and 2008-2012, the present work investigated the channel changes in terms of shape parameter change rate under the same controlling water level in each flooding season at the channel cross-sections. Results showed that most of the change rates of the parameters evidently increased over a flooding season in both periods. However, the change rate of each parameter at the cross-sections decreased evidently in the latter period, compared with the former period. At the same time, the distribution pattern of the change rate of the shape parameters along the cross-sections thus changed from a convex curve in the former period to an S-shaped curve in the latter period. The obvious decrease of the change rates is related to the joint operation of the Liujiaxia and Longyangxia reservoirs. The reservoirs stored a large volume of water and decreased the peak discharge and maximum velocity in the flooding season; as a result, the erosion ability of the flood decreased accordingly. With the joint operation of the large reservoirs, the Inner Mongolian channel shrunk markedly. Therefore, the channel will present the possibility of an extreme flood in the future. Consequently, it is reasonable to adjust the function of the reservoirs in future. The total water and sediment discharges and the peak discharge in flooding seasons should be effectively controlled. Continuous shrinkage of the channel can thus be avoided and it can be ready for a potential extreme flood.

The formation of Danxia landscapes is too slow to be observed in our life time and the paleoclimates in which Danxia landscapes developed are significantly different from the present. Thus, this study adopted experimental approaches to examine the lithological and paleoclimatic control on the formation of various landscape morphologies in the Mt. Danxiashan, South China. A total of 122 rock samples were collected from a range of Danxia landscape morphologies such as white spots, small and large through caves, honeycomb caves, horizontal grooves, natural bridges, stone pillars, and squama stones. Analyses of the collected samples were conducted in different kinds of experiments, including uniaxial mechanical strength testing; rock resistance against sulfuric acid erosion, freezing, and thawing; X-ray fluorescence spectrometry (XRF) analysis; inductively coupled plasma mass spectrometry (ICP-MS) analysis; and identification analysis under a polarizing microscope. The results indicated that the formation of the various Danxia landscape morphologies could result from one or more of the following processes: differential erosion due to lithological difference, chemical dissolution and recrystallization, freezing and thawing actions, acid corrosion, weathering, lateral erosion of river flows, and tectonic uplifts. Water erosion in humid monsoon climate and the alternations of intensive freezing and thawing actions in the Quaternary glacial stages and the interglacial stages could have had great influences on the formation of Danxia landscape topographies.

Permafrost degradation triggered by a warming climate induces significant changes in soil conditions, and further contributes to apparent impacts on vegetation. However, much less is known regarding the difference in net primary productivity (NPP) and the relationships between NPP and warming temperature among different vegetation types and various types of permafrost zone on the Tibetan Plateau. Consequently, remotely sensed land surface temperature (LST) and NPP from the MODIS platform were used to investigate the response of vegetation NPP to warming climate, and the correlations were scaled up for the study region. Our results indicated a notable increase of NPP from west to east, and significantly increased annual NPP along with the increased LST from 2000 to 2010 in the permafrost zone of the Tibetan Plateau. Meanwhile, the increased NPP for various vegetation types and in different types of permafrost zone with relation to warming temperature was revealed. NPP in the continuous permafrost zone had the greatest sensitivity to the changing LST, and forest NPP presented the most obvious response. Positive correlations between NPP and LST at various scales indicated the enhanced effects of warming LST on vegetation carbon sequestration in the permafrost zone of the Tibetan Plateau. In view of the notable response of NPP to warming temperature on this plateau, remote sensing needs to be further employed to reveal the status of permafrost degradation and its related effects on vegetation.

People’s decisions of residential mobility in housing market and decisions of job change in labor market play an essential role in the formation and dynamics of urban spatial structure. This paper investigates the relationship between residential relocation and job change and its heterogeneity using a large-scale survey of residential living satisfaction and preferences in Beijing. Several conclusions are drawn as follows: 1) People’s decisions of residential mobility are significantly positively correlated with their decisions of job change, indicating that these two-dimensional decisions are in fact a correlated decision process rather than two independent decision processes. 2) There is heterogeneity in the correlated decisions of residential mobility and job change. More specifically, the interrelationship between the decisions of residential mobility and job change among people without Beijing hukou, renters and single-worker households is more intensive than people with Beijing hukou, homeowners and multi-worker households. In addition, there is heterogeneity in the determinants of residential relocation and job change between groups with different types of housing tenure, household registration status and family employment structure. 3) For renters, commuting time can significantly increase the probability of residential relocation, which indicates that residents of different socioeconomic attributes have very different responses to commuting time costs.

Research has shown that there has been a significant change in the quantitative relationship between urbanization and economic development over the past 50 years. As a result of this change, the Chenery model is no longer capable of performing a comparative analysis of these parameters. We carried out a regression analysis of the normal form of the relation between urbanization and economic development on the basis of the Chenery model. We used empirical data from 149 countries and regions from 1990 to 2009 and adopted the double logarithmic model, introducing a time series variable for urbanization. From 1990 to 2009, with a per capita gross national income remaining between USD 1000 and 10,000, the urbanization rate changed from 17.78 to 60.36% and the relational matching data changed accordingly, although the upper limit of the rate of urbanization remained at about 75%. Urbanization in countries with a smaller population size was more affected by economic development than urbanization in countries with large and medium sized populations.

Land-use efficiency is low for the urban agglomeration of China. High-speed transportation construction has been an important factor driving land use change. It is critically important to explore the spatial relationship between the high-speed transportation superiority degree and land-use efficiency. We built a model to evaluate the benefits of convenient high-speed transportation using the relative density of highways and the distance from high-speed rail stations and airports as a metric. We used 42 counties of the Shandong Peninsula urban agglomeration as an example. Land-use efficiency was calculated by a DEA model with capital, labor, economic benefits and environmental benefits as input and output factors. We examined the spatial relationships between high-speed transport superiority degree and land-use efficiency and obtained the following results. First, there are significant spatial differences in the relationships between the high-speed transportation superiority degree and land-use efficiency. Taking the two major cities of Jinan and Qingdao as the hubs, the core surrounding counties show significant spatial relationship between land-use efficiency and the high-speed transportation superiority degree. Spatial correlation declines as the distance from the hubs increases. Land-use efficiency is less than high-speed transportation convenience in areas along the transportation trunks that are distant from the hub cities. Correlation is low in areas that are away from both hub cities and transportation trunk routes. Second, high-speed transportation has a positive relationship with land-use efficiency due to the mechanism of element agglomeration exogenous growth. Third, high-speed transportation facilitates the flow of goods, services and technologies between core cities and peripheral cities as space spillover (the hub effect). This alters the spatial pattern of regional land-use efficiency. Finally, the short-board effect caused by decreased high-speed transport construction can be balanced by highway construction and the proper node layouts of high-speed rail stations and airports, resulting in a well-balanced spatial pattern of land-use efficiency.

Discussions regarding the functional transformation of agricultural utilization and the mechanisms that underlie these changes within the Three Gorges Reservoir Area (TGRA) reflect variations in the relationship between people and their environment in China’s central and westerns part, an area of mountains and reservoirs. A clear understanding of these changes also provides the scientific basis for the development of multi-functional agriculture in typical mountainous areas. Five counties were selected for analysis in this study from the hinterland of the TGRA; we analyzed changes in farmland scaling and corresponding underlying mechanisms by defining the concepts of “Scaling Farmland” (SF) and by using the software packages ArcGIS10.2, SPSS, and Geographical Detectors. The results of this analysis show that sources of increased SF have mainly comprised cultivated and shrub land. Indeed, with the exception of some alpine off-season vegetables, SF growth has mainly occurred in low altitude areas and in places where the slope is less than 30°. We also show that spatial changes in various SF types have also been substantially different, but in all cases are closely related to road and township administrative centers. Natural factors at the patch level, including elevation and slope, have contributed significantly to SF, while at the township level, underlying socioeconomic and humanistic factors have tended to include road traffic and agricultural population density. In contrast, at the regional level, underlying driving forces within each have tended to be more significant than overall study area scale. We show that while changes in, and the development of, SF have been driven by numerous factors, agricultural policies have always been amongst the most important. The results clearly elucidate general land use transformation patterns within the mountain regions of western China.

Rapid urbanization and continuous loss of rural labor force has resulted in abandonment of large areas of farmland in some regions of China. Remote sensing technology can indirectly help detect abandoned farmland size and quantity, which is of great significance for farmland protection and food security. This study took Qingyun and Wudi counties in Shandong Province as a study area and used CART decision tree classification to compile land use maps of 1990-2017 based on Landsat and HJ-1A data. We developed rules to identify abandoned farmland, and explored its spatial distribution, duration, and reclamation. CART accuracy exceeded 85% from 1990-2017. The maximum abandoned farmland area was 5503.86 ha during 1992-2017, with the maximum rate being 5.37%. Farmland abandonment rate was the highest during 1996-1998, and abandonment trend decreased year by year after 2006. Maximum abandonment duration was 15 years (1992-2017), mostly within 4 years and only a few exceeded 10 years. From 1993-2017, the maximum reclaimed abandoned farmland was 2022.3 ha, and the minimum ~20 ha. The maximum reclamation rate was 67.44%m, with annual average rate being 31.83%. This study will help analyze farmland abandonment driving forces in the study area and also provide references to identify abandoned farmland in other areas.

Topographical relief is a key factor that limits population distribution and economic development in mountainous areas. The limitation is especially apparent in the mountain-plain transition zone. Taking the transition zone between the Qinling Mountains and the North China Plain (i.e. the mountainous area in western Henan Province) as an example and based on the 200-m resolution DEM data, we used the mean change-point analysis to determine the optimal statistical unit for topographical relief, and thereafter extracted the relief degree. Taking the 1:100,000 land use data, township population and county-level industrial data, population and economic spatial models were constructed, and 200-m resolution grid population and economic density maps were generated. Afterwards, statistical analysis was carried out to quantitatively reveal the impact of topographical relief on population and economy. In addition, the impacts of other topographical factors were discussed. The results showed the following. (1) The relief degree in western Henan is generally low, where 58.6% of the regional topography does not exceed half the height of a reference mountain (relative elevation ≤250 m). Spatially, the relief degree is high in the west while low in the east, and high in the middle while low in the north and south. There is a positive correlation between relief degree and elevation, and a much stronger correlation between relief degree and slope. (2) The linear fitting degree between the population and economic validation data and the corresponding simulation data are 0.943 and 0.909, respectively, indicating that the spatialized results can reflect the actual population and economic distribution. (3) The impact of topographical relief on population and economy was stronger than that of other topographical factors. The relief degree showed a good logarithmic fit relationship with population density (0.911) and economic density (0.874). Specifically, 88.65% of the population lives in areas where the topographical relief is ≤0.5 and 88.03% of the gross regional product was from areas where the relief is ≤0.3. Compared with the population distribution, the economic development showed an obvious agglomeration trend towards low relief areas.

Lateral migration of the Bhagirathi River temporally creates unavoidable geomorphic hazards in West Bengal, India. The Bhagirathi River flows SW for ~67.30 km between the confluence point of Ajay and Jalangi rivers in East Burdwan and Nadia districts of West Bengal. The course of Bhagirathi is notably migration prone and cultivates problematic changes along its course over time. In the study, we have looked into its migration tendency and unpredictability for past 238 years and then predicted the lateral shifting of river centerline using temporal satellite imageries - Landsat-5 (TM) of 1987 (8, December), 1995 (28, January), 2005 (7, January) and LISS-IV satellite imagery (2017, 5 January);SOI Toposheet - 1968-1969 (79A/2, 79A/3, 79A/6 and 79A/7) and Rennell’s map of 1779. Other highlights are the quest of fluvial features, oxbow lakes, mid-channel bars, channel migration rate, meander geometry, channel sinuosity in different parts of river course and the parts that experience intensive bank erosion. The entire river course has been subdivided into three segments; viz. reaches A, B and C. Investigation displays that degree of sinuosity decreases from its anterior course (1968) to the existing course (2017). Reach-specific outputs display that reach B is highly sinuous (SI value 1.94 in 2017) and SI increases temporarily, whereas for reaches A and C it decreases with time. The rate of migration is higher in reach B than that in reaches C and A. The study displays a notably decreasing trend of migration in comparison with its previous lateral migration and shows that the migration nature over time is intensively inconsistent and unpredictable except very few portions of the river course. The nature of deposition within the river channel shows an unstable behavior during the entire period of the study. Meander geometry depicts a rapid change of river course innate to meander bends and shows a higher rate of migration by meander loop cut-off rather than lateral migration that reflects the inconsistency, erosion vulnerability and unpredictable nature of migration. The present work offers a valuable source to comprehend channel changes in Bhagirathi River and serve as an efficacious base for river-bank migration and erosion hazard planning and management.

Poverty is a key issue restricting rural sustainable development; concurrently, regional land degradation impedes agricultural development and rural revitalization. China faces severe land degradation and deepening rural poverty under the context of rapid urbanization. To address these challenges, sustainable land use is an important tool in our society’s economic development. Rural engineering, including rural land consolidation, reclamation, restoration, reallocation, improvement, and development, is the most direct and effective way to achieve rural sustainable poverty alleviation. This study clarifies the framework between land engineering and rural poverty alleviation, and introduces land engineering technologies, newly created land utilization practices, and the contributions to poverty alleviation in representative degraded land regions. Land engineering can increase land quantity, improve land quality, enhance land ecological function, and promote man-land system coupling. Further, it can erase rural poverty by increasing county revenue and households’ income, lead to industrial development, and improve living environment. Specifically, degraded sandy land, gully land, hollowed construction land, and barren hilly land are transformed into productive land by improving the land structure. Innovated land engineering technologies and sustainable land utilization modes can provide the basic theories and reference approaches for rural poverty alleviation. Identifying obstacles to effective land and corresponding engineering practices are crucial to regional land exploitation and development, improving quality of life and alleviating rural poverty.

Quantitative characterization of environmental characteristics of cropland (ECC) plays an important role in maintaining sustainable development of agricultural systems and ensuring regional food security. In this study, the changes in ECC over the Songnen Plain, a major grain crops production region in Northeast China, were investigated for the period 1990-2015. The results revealed significant changes in climate conditions, soil physical properties and cropland use patterns with socioeconomic activities. Trends in climate parameters showed increasing temperature (+0.49°C/decade, p < 0.05) and decreasing wind speed (-0.3 m/s/decade, p < 0.01) for the growing season, while sunshine hours and precipitation exhibited non-significant trends. Four topsoil parameters including soil organic carbon (SOC), clay, bulk density and pH, indicated deteriorating soil conditions across most of the croplands, although some do exhibited slight improvement. The changing amplitude for each of the four above parameters ranged within -0.052 to 0.029 kg C/kg, -0.38 to 0.30, -0.60 to 0.39 g/cm³, -3.29 to 2.34, respectively. Crop production significantly increased (44.0 million tons) with increasing sown area of croplands (~2.5 million ha) and fertilizer application (~2.5 million tons). The study reveals the dynamics of ECC in the Songnen Plain with intensive cultivation from 1990 to 2015. Population growth, economic development, and policy reform are shown to strongly influence the spatiotemporal changes in cropland characteristics. The study potentially provides valuable scientific information to support sustainable agroecosystem management in the context of global climate change and national socioeconomic development.