Articles in press have been peer-reviewed and accepted, which are not yet assigned to volumes /issues, but are citable by Digital Object Identifier (DOI).
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Surface Regional Heat (Cool) Island Effect and Its Diurnal Differences in Arid and Semiarid Resource-based Urban Agglomerations
Yan CHEN, Miaomiao XIE, Bin CHEN, Huihui WANG, Yali TENG
Accepted Manuscript  doi: 10.1007/s11769-022-1324-y
[Abstract](3) [FullText HTML](2)
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With the rapid development of urban agglomerations in northwest arid and semiarid regions of China, the scope of the urban heat island (UHI) effect has gradually expanded and gradually connected, and has formed a regional heat island (RHI) with a larger range of impact to the regional environment. However, there are few studies on the heat island effect of urban agglomerations in arid and semiarid regions, so this paper selects the urban agglomeration of Hohhot, Baotou and Ordos (HBO) of Inner Mongolia, China as the study area. Based on the 8-day composite Moderate-resolution Imaging Spectroradiometer (MODIS) surface temperature data (156 scenes in all) and land use maps for 2005, 2010, and 2015, we analyze the spatiotemporal distributions of regional heat (cool) islands (RH(C)I) and the responses of surface temperatures to land-use changes in the diurnal and interannual surface cities. The results showed that: 1) from 2005 to 2015, urban areas showed the cold island effect during the day, with the area of the cold island showing a shrinking feature; at night, they showed the heat island effect, with the area of the heat island showing a first decrease and then an increase. 2) From 2005 to 2015, the land development (unutilized land to building land) brings the greatest temperature increase (∆T = 1.36°C) during the day, while the greatest temperature change at night corresponds to the conversion of cultivated land to building land (∆T = 0.78°C) exhibited the largest changes at night. From 2010 to 2015, the land development (grassland to building land) bring the greatest temperature increase (∆T = 0.85°C) during the day, while the great temperature change at night corresponds to the conversion of water areas to building land (∆T = 1.38°C) exhibited the largest changes at night. Exploring the spatial and temporal evolution of surface urban heat (cool) islands in urban agglomerations in arid and semiarid regions will help to understand the urbanization characteristics of urban agglomerations and provide a reference for the formulation of policies for the coordinated and healthy development of the region and co-governance of regional environmental problems.
Spatial Structure of China’s E-commerce Express Logistics Network Based on Space of Flows
Yuanjun LI, Qitao WU, Yuling ZHANG, Guangqing HUANG, Hongou ZHANG
Accepted Manuscript  doi: 10.1007/s11769-022-1322-0
[Abstract](64) [FullText HTML](32)
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The intermediate link compression characteristics of e-commerce express logistics networks influence the traditional mode of circulation of goods and economic organization, and alter the city spatial pattern. Based on the theory of space of flows, this study adopts China Smart Logistics Network relational data to build China’s e-commerce express logistics network and explore its spatial structure characteristics through social network analysis (SNA), the PageRank technique, and geospatial methods. The results are as follows: the network density is 0.9270, which is close to 1; hence, indicating that e-commerce express logistics lines between Chinese cities are nearly complete and they form a typical network structure, thereby eliminating fragmented spaces. Moreover, the average minimum number of edges is 1.1375, which indicates that the network has a small world effect and thus has a high flow efficiency of logistics elements. A significant hierarchical diffusion effect was observed in dominant flows with the highest edge weights. A diamond-structured network was formed with Shanghai, Guangzhou, Chongqing, and Beijing as the four core nodes. Other node cities with a large logistics scale and importance in the network are mainly located in the 19 city agglomerations of China, revealing the fact that the development of city agglomerations is essential for promoting the separation of experience space and changing the urban spatial pattern. This study enriches the theory of urban networks, reveals the flow laws of modern logistics elements, and encourages coordinated development of urban logistics.
Spatio-temporal Evolution of the Rural Regional System and Its Evolution Mechanism in Huang-Huai-Hai Area of China
Mingyang CHENG, Huiling CHEN
Accepted Manuscript  doi: 10.1007/s11769-022-1323-z
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The problem of rural development arises from the evolution of rural regional system. It is urgent to deepen the research on the evolution process and mechanism of rural regional system. However, there are relatively few studies on rural development from the perspective of the evolution process, driving mechanism and evolution mechanism of rural regional system. Therefore, this study took Huang-Huai-Hai Area for example, started with the systematicness of the rural regional system, the spatio-temporal pattern and driving mechanism of rural regional system evolution, and further summarized and refined the evolution mechanism of the rural regional system. The methods of spatial pattern analysis, gray correlation degree and geographical detection were adopted. The results showed that the problems in rural areas were often dominated by one factor and produced by the joint action of many factors. Factors such as county urbanization, county economy, county public service, agricultural mechanization, surrounding cities and convenient transportation will affect the evolution of rural regional systems. Based on the evolution of the elements in the rural regional system, the evolution types of rural regional system can be divided into decline type, equilibrium type and growth type. This study can provide a reference for understanding the process of rural rise and fall and can also guide rural revitalization and rural sustainable development.
Incorporating Exercise Efficiency to Evaluate the Accessibility and Capacity of Medical Resources in Tibet, China
Li WANG, Linsheng YANG, Binggan WEI, Hairong LI, Hongyan CAI, Jixia HUANG, Xing YUAN
Accepted Manuscript  doi: 10.1007/s11769-022-1321-1
[Abstract](8) [FullText HTML](3)
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Accessibility and capacity of medical resources are key for the health care and emergency response, while the efficiency of the medical resources is very much limited by hypoxia in Tibet, China. Through introducing exercise efficiency, this study explores the accessibility of township residence to county-ship medical resources in Tibet using weighted mean travel time (WMT), and evaluates the medical capacity accordingly. The results show that: 1) the average travel time of township residence to county-level hospital is around 2 h by motor vehicle in Tibet. More than half of the population can not reach the county-ship hospital within 1 h, 33.24% of the population can not reach within 2 h, and 3.75% of the population can not reach within 6 h. 2) When considering the catchment of the medical resources and the population size, the WMT of the county-ship medical resources ranges from 0.25 h to 10.92 h. 3) After adjusted by travel time and exercise efficiency, the county-ship medical capacity became more unequal, with 38 out of 74 counties could not meet the national guideline of 1.8 medical beds per 1000. 4) In total, there are 17 counties with good WMT and sufficient medical resources, while 13 counties having very high WMT and low capacity of medical resources in Tibet. In the end, suggestions on medical resources relocation and to improve the capacity are provided. This study provides a method to incorporate exercise efficiency to access the accessibility and evaluate medical capacity that can be applied in high altitude ranges.
Multi-source Data-driven Identification of Urban Functional Areas: A Case of Shenyang, China
Bing XUE, Xiao XIAO, Jingzhong LI, Bingyu ZHAO, Bo FU
Accepted Manuscript  doi: 10.1007/s11769-022-1320-2
[Abstract](6) [FullText HTML](2)
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Urban functional area (UFA) is a core scientific issue affecting urban sustainability. The current knowledge gap is mainly reflected in the lack of multi-scale quantitative interpretation methods from the perspective of human-land interaction. In this paper, based on multi-source big data include 250 m × 250 m resolution cell phone data, 1.81 × 105 Points of Interest (POI) data and administrative boundary data, we built a UFA identification method and demonstrated empirically in Shenyang City, China. We argue that the method we built can effectively identify multi-scale multi-type UFAs based on human activity and further reveal the spatial correlation between urban facilities and human activity. The empirical study suggests that the employment functional zones in Shenyang City are more concentrated in central cities than other single functional zones. There are more mix functional areas in the central city areas, while the planned industrial new cities need to develop comprehensive functions in Shenyang. UFAs have scale effects and human-land interaction patterns. We suggest that city decision makers should apply multi-sources big data to measure urban functional service in a more refined manner from a supply-demand perspective.
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05 November 2022, Volume 32 Issue 6
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Spatiotemporal Evolution of West Africa’s Urban Landscape Characteristics Applying Harmonized DMSP-OLS and NPP-VIIRS Nighttime Light (NTL) Data
Douglas SONO, Ye WEI, Zuoqi CHEN, Ying JIN
2022, 32(6): 933-945.   doi: https://doi.org/10.1007/s11769-022-1313-1
[Abstract](17) [FullText HTML](8) [PDF 2144KB](3)
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Investigating urban expansion patterns aids in the management of urbanization and in ameliorating the socioeconomic and environmental issues associated with economic transformation and sustainable development. Applying Harmonized Defense Meteorological Satellite Program-Operational Line-scan System (DMSP-OLS) and the Suomi National Polar-Orbiting Partnership-Visible Infrared Imagery Radiometer Suite (NPP-VIIRS) Nighttime Light (NTL) data, this paper investigated the characteristics of urban landscape in West Africa. Using the harmonized NTL data, spatial comparison and empirical threshold methods were employed to detect urban changes from 1993 to 2018. We examined the rate of urban change and calculated the direction of the urban expansion of West Africa using the center-of-gravity method for urban areas. In addition, we used the landscape expansion index method to assess the processes and stages of urban growth in West Africa. The accuracy of urban area extraction based on NTL data were R2 = 0.8314 in 2000, R2 = 0.8809 in 2006, R2 = 0.9051 in 2012 for the DMSP-OLS and the simulated NPP-VIIRS was R2 = 0.8426 in 2018, by using Google Earth images as validation. The results indicated that there was a high rate and acceleration of urban landscapes in West Africa, with rates of 0.016 0, 0.017 3, 0.018 9, and 0.068 6, and accelerations of 0.31, 0.42, 0.54, and 0.90 for the periods of 1998–2003, 2003–2008, 2008–2013, and 2013–2018, respectively. The expansion direction of urban agglomeration in West Africa during 1993–2018 was mainly from the coast to inland. However, cities located in the Sahel Region of Africa and in the middle zone expanded from north to south. Finally, the results showed that the urban landscape of West Africa was mainly in a scattered and disordered ‘diffusion’ process, whereas only a few cities located in coastal areas experiencing the process of ‘coalescence’ according to urban growth phase theory. This study provides urban planners with relevant insights for the urban expansion characteristics of West Africa.
Polarization or Diffusion? Spatio-temporal Evolution of Urban Technological Innovation Capacity in China’s Five Urban Agglomerations
Jinxian CAO, Shengning LI, Qingyuan YANG
2022, 32(6): 946-962.   doi: https://doi.org/10.1007/s11769-022-1309-x
[Abstract](474) [FullText HTML](234) [PDF 8647KB](11)
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Under the background of collaborative innovation, innovation spillovers at urban agglomeration (UA) level is an important issue but rarely discussed. Using balanced panel data of innovation activities in China’s five UAs from 2003 to 2016, this paper shows spatio-temporal evolution process of their technological innovation capacity with discussing polarization-diffusion patterns, and simultaneously examines driving factors of that evolution processes. We report three main findings: 1) there is a high degree of concentration in technological innovation capacity distribution within all China’s five UAs, linked by economic and innovation collaboration. 2) Innovation capacity increase of China’s five UAs is driven by government’s investment in science and technology (S&T) to a large extent, followed by influences of infrastructure facilities construction, human capital for S&T, as well as transformation of industrial structure, with great disparities emerged between UAs in our sample period. 3) While the intra-region innovation gaps are reducing in Yangtze River Delta Urban Agglomeration (YRD) with obvious innovation diffusion, urban agglomeration in middle reaches of the Yangtze River (MYR) is still dominated by innovation polarized growth. Differences in polarization-diffusion patterns between these two UAs may be explained by opposite returns of industrial structure and internet infrastructure. Our findings contribute to more effective policy making in promoting innovation development when reducing regional inequality through innovation diffusion.
Spatial Distribution of High-temperature Risk with a Return Period of Different Years in the Yangtze River Delta Urban Agglomeration
Guixin ZHANG, Shisheng WANG, Shanyou ZHU, Yongming XU
2022, 32(6): 963-978.   doi: https://doi.org/10.1007/s11769-022-1314-0
[Abstract](4) [FullText HTML](2) [PDF 4472KB](0)
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Against the background of global warming, research on the spatial distribution of high-temperature risk is of great significance to effectively prevent the adverse effects of high temperatures. By using air temperature data from 1951 to 2018 measured by meteorological stations located in the Yangtze River Delta urban agglomeration, the daily maximum air temperature distribution is interpolated at a resolution of 1 km based on the local thin disk smooth spline function; the high-temperature threshold for return periods of 5, 10, 20 and 30 yr are then calculated by using the generalized extreme value method. The yearly average high-temperature intensity and high-temperature days are finally calculated as high-temperature danger factors. Socioeconomic statistical data and remotely sensed image data in 2018 are used as the background data to calculate the spatial distribution of high-temperature vulnerability factors and prevention capacity factors, which are then used to compute the high-temperature risk index during different recurrence periods in the Yangtze River Delta urban agglomerations. The results show that the spatial distribution features of high-temperature risk in different return periods are similar. The high-temperature risk index gradually increases from northeast to southwest and from east coast to inland, which has obvious latitude variation characteristics and a relationship with the comprehensive influence of the underlying surface and urban scale. In terms of time variation, the high-temperature risk index and its spatial distribution difference gradually decreases with increasing return period. In different cities, the high-temperature risk in the central area of the city is generally higher than that in the surrounding suburban areas. Jinhua, Hangzhou of Zhejiang Province and Xuancheng of Anhui Province are the top three cities with high-temperature risk in the study area.
Improving the Interpretability and Reliability of Regional Land Cover Classification by U-Net Using Remote Sensing Data
Xinshuang WANG, Jiancheng CAO, Jiange LIU, Xiangwu LI, Lu WANG, Feihang ZUO, Mu BAI
2022, 32(6): 979-994.   doi: https://doi.org/10.1007/s11769-022-1315-z
[Abstract](9) [FullText HTML](4) [PDF 8487KB](1)
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The accurate and reliable interpretation of regional land cover data is very important for natural resource monitoring and environmental assessment. At present, refined land cover data are mainly obtained by manual visual interpretation, which has the problems of heavy workload and inconsistent interpretation scales. Deep learning has greatly improved the automatic processing and analysis of remote sensing data. However, the accurate interpretation of feature information from massive datasets remains a difficult problem in wide regional land cover classification. To improve the efficiency of deep learning-based remote sensing image interpretation, we selected multisource remote sensing data, assessed the interpretability of the U-Net model based on surface spatial scenes with different levels of complexity, and proposed a new method of stereoscopic accuracy verification (SAV) to evaluate the reliability of the classification result. The results show that classification accuracy is more highly correlated with terrain and landscape than with other factors related to image data, such as platform and spatial resolution. As the complexity of surface spatial scenes increases, the accuracy of the classification results mainly shows a fluctuating declining trend. We also find the distribution characteristics from the SAV evaluation results of different land cover types in each surface spatial scene. Based on the results observed in this study, we consider the distinction of interpretability and reliability in diverse ground object types and design targeted classification strategies for different surface scenes, which can greatly improve the classification efficiency. The key achievement of this study is to provide the theoretical basis for remote sensing information analysis and an accuracy evaluation method for regional land cover classification, and the proposed method can help improve the likelihood that intelligent interpretation can replace manual acquisition.
Spatial-temporal Evolution Analysis on Land Use Multifunctionality in the China-Vietnam Border Area
Tianneng HUANG, Nian WANG
2022, 32(6): 995-1012.   doi: https://doi.org/10.1007/s11769-022-1316-y
[Abstract](6) [FullText HTML](3) [PDF 2257KB](2)
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Exploring the spatial and temporal evolution characteristics of the border land use multifunctionality (LUMF) provides insights for taking advantage of border land use and optimizing border land use policies. Based on the improved Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) mode, this study identifies and evaluates the LUMFs in the China-Vietnam border area between 2000 and 2018 from the perspectives of agricultural production, social security, ecological service, landscape recreation, and national security. The results show that: 1) The comprehensive land use functions in most counties and cities continued to be improved. 2) The comprehensive land use function exhibits remarkable spatial divergence and aggregation characteristics. The high-value area of the agricultural production function and social security function evolves from the east to the west. In addition, the spatial evolution of ecological service function is complicated, without an obvious spatial divergence and aggregation pattern. The landscape recreation function shows different spatial differentiation characteristics in the early and middle stage, and forms a large cluster in the later stage. Finally, the spatial evolution pattern of the national security function is significant. 3) Designing differentiated border land policies, improving border land use security, and establishing a long-term mechanism for ecological protection and ecological compensation can aid in optimizing the LUMF level in the border area.
Spatial Distribution Characteristics and Influencing Factors of Agricultural Specialized Villages in Guangdong Province, China
Ren YANG, Xin ZHANG, Qian XU
2022, 32(6): 1013-1034.   doi: https://doi.org/10.1007/s11769-022-1317-x
[Abstract](6) [FullText HTML](3) [PDF 3878KB](3)
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China is vigorously implementing a rural revitalization strategy with the prosperity of rural industries as the primary goal. The characteristic economy of ‘One Village One Product’ (OVOP) is particularly significant in promoting rural revitalization and increasing farmers’ income. Accurately identifying the spatial distribution characteristics and influencing factors of agricultural specialized villages (ASVs) under OVOP provides a preliminary research basis for constructing the theoretical framework of specialization and clustering of rural industrial development. This study takes Guangdong Province, China as an example, using kernel density estimation, Ripley’s K function, geometric fractals, principal component regression and other methods to identify the spatial distribution characteristics and influencing factors of ASVs. It was found that the ASVs in Guangdong Province are dominated by the planting industry, with an uneven number in space and a multi patch distribution. Specifically, ASVs are mainly distributed in the Chaoshan Plain in the eastern Guangdong, the northern mountainous area of Guangzhou, and the eastern part of Maoming City. Its spatial distribution mode obeys the aggregation distribution pattern at the scale of province, region and municipality (prefecture-level city). In addition, the formation and development of ASVs are affected by multiple internal and external factors. The influence of basic factors such as natural environmental conditions is gradually weakening, while the influence of social and economic factors such as market demand is gradually increasing. This study can enrich the research results of ASVs and provide guidance and reference for the long-term and high-quality development of rural industry revitalization.
Path of Rural Sustainable Development Based on the Evolution and Interaction of Rural Functions: A Case Study of Chongqing Municipality, China
Ruilian DAI, Cheng WANG, Xinyue WU
2022, 32(6): 1035-1051.   doi: https://doi.org/10.1007/s11769-022-1312-2
[Abstract](83) [FullText HTML](41) [PDF 23188KB](8)
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In order to investigate the evolutionary characteristics of rural functions and their interaction, 37 districts and counties in Chongqing, China are used as research objects to measure the level of rural functions and analyze the interaction between rural functions using entropy value method and spatial autocorrelation method. The results show that from 2009 to 2019, the three main functions of production, living and ecology in Chongqing’s villages have been greatly enhanced, especially the production function. On the whole, the production and living functions are stronger in the western part, while the ecological functions are significant in the eastern and southern parts of Chongqing, with some differences in local spatial characteristics. This finding is consistent with the regional economic and social development of Chongqing. In addition, the interaction between rural functions is also evident. In general, production and living functions are mainly expressed in synergistic relationships. Ecological and production functions, including ecological and subsistence functions, mainly present a trade-off relationship. The interactions between rural functions also show clear spatial and temporal differences. In addition, different regions have different comparative advantage functions, and in this study, the counties of Chongqing are classified into four types. Policy makers are advised to adopt different measures according to the different types to promote sustainable rural development by coordinating the ‘production-living-ecological’ functions of rural areas. This study reveals the spatio-temporal evolution of rural functions and the interaction between rural functions, which can provide theoretical support and practical reference for rural revitalisation and sustainable development.
Coupling and Coordination Characteristics and Influencing Factors of the Livable Environment System for the Elderly in China
Xiaohong CHEN, Mingxuan ZHANG, Ying WANG, Xiaoqing XU, Shuang LIU, Lingyu MA
2022, 32(6): 1052-1068.   doi: https://doi.org/10.1007/s11769-022-1283-3
[Abstract](225) [FullText HTML](165) [PDF 7490KB](80)
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The construction of a livable environment for the elderly is an important measure to address the challenges of aging and improve their livelihood and well-being. Based on China’s national conditions and combined with the actual development needs of the cities, it is of great significance to explore the coupling and coordination characteristics and influencing factors within the livable environment system for the elderly for the coordination and stable development. This article was based on the three subsystems of ‘living service environment, socioeconomic environment and ecological livable environment’, following the research framework of ‘process-pattern-trend-impact’, constructs an evaluation index system for the livable environment for the elderly. Entropy weight-TOPSIS evaluation model, coupling coordination degree model, center of gravity and standard deviation ellipse model and the geographic detector model were used starting from the evolution of coupling coordination types to study the spatial and temporal pattern and dynamic trend characteristics and influencing factors of internal coupling coordination types in the livable environment system for the elderly from 2010 to 2019. The results showed that: 1) The coordinated development of life service environment system and ecological livable environment system (LE) and socioeconomic environment system and ecological livable environment system (SE) in the livable environment for the elderly decreased from the intermediate coordination level coordination areas to the low-level quality improvement and optimization areas: coordinated transition type. The overall development level of life service environment system and socioeconomic environment system (LS) was low, and it was always at a low level. 2) The coupling degree of livable environment system for the elderly was high, the coupling coordination type shown a gradually decreasing layer structure with Zhejiang, Beijing and Guangdong high-level leading demonstration areas as the axis belt. 3) The coupling coordination center of the elderly livable environment system was located in Henan, and the standard deviation ellipse was distributed in the northeast-southwest direction. The development center and the ellipse of the high-level leading demonstration areas and the intermediate coordination level areas were concentrated in the central and eastern regions, while the low-level coordination areas for improving quality and efficiency are mainly located in the western region. 4) Urban development, green facilities, infrastructure, government macroscopic regulation and control, economic stimulus, and housing construction were all important factors affecting the coordinated development of the livable environment system for the elderly, exerting a varying degree of effect on the level of coordinated development of various types of systems.
Quantitative Assessment of the Relative Contributions of Climate and Human Factors to Net Primary Productivity in the Ili River Basin of China and Kazakhstan
Liang LIU, Jingyun GUAN, Wanqiang HAN, Xifeng JU, Chen MU, Jianghua ZHENG
2022, 32(6): 1069-1082.   doi: https://doi.org/10.1007/s11769-022-1311-3
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It is necessary to quantitatively study the relationship between climate and human factors on net primary productivity (NPP) inorder to understand the driving mechanism of NPP and prevent desertification. This study investigated the spatial and temporal differentiation features of actual net primary productivity (ANPP) in the Ili River Basin, a transboundary river between China and Kazakhstan, as well as the proportional contributions of climate and human causes to ANPP variation. Additionally, we analyzed the pixel-scale relationship between ANPP and significant climatic parameters. ANPP in the Ili River Basin increased from 2001 to 2020 and was lower in the northeast and higher in the southwest; furthermore, it was distributed in a ring around the Tianshan Mountains. In the vegetation improvement zone, human activities were the dominant driving force, whereas in the degraded zone, climate change was the primary major driving force. The correlation coefficients of ANPP with precipitation and temperature were 0.322 and 0.098, respectively. In most areas, there was a positive relationship between vegetation change, temperature and precipitation. During 2001 to 2020, the basin’s climatic change trend was warm and humid, which promoted vegetation growth. One of the driving factors in the vegetation improvement area was moderate grazing by livestock.
Application of Spatially Distributed Calibrated Hydrological Model in Evapotranspiration Simulation of Three Gorges Reservoir Area of China: A Case Study in the Madu River Basin
Junhong CHEN, Lihua ZHANG, Peipei CHEN, Yongming MA
2022, 32(6): 1083-1098.   doi: https://doi.org/10.1007/s11769-022-1318-9
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Evapotranspiration (ET) is the key to the water cycle process and an important factor for studying near-surface water and heat balance. Accurately estimating ET is significant for hydrology, meteorology, ecology, agriculture, etc.. This paper simulates ET in the Madu River Basin of Three Gorges Reservoir Area of China during 2009−2018 based on the Soil and Water Assessment Tool (SWAT) model, which was calibrated and validated using the MODIS (Moderate-resolution Imaging Spectroradiometer)/Terra Net ET 8-Day L4 Global 500 m SIN Grid (MOD16A2) dataset and measured ET. Two calibration strategies (lumped calibration (LC) and spatially distributed calibration (SDC)) were used. The basin was divided into 34 sub-basins, and the coefficient of determination (R2) and Nash-Sutcliffe efficiency coefficient (NSE) of each sub-basin were greater than 0.6 in both the calibration and validation periods. The R2 and NSE were higher in the validation period than those in the calibration period. Compared with the measured ET, the accuracy of the model on the daily scale is: R2= 0.704 and NSE = 0.759 (SDC results). The model simulation accuracy of LC and SDC for the sub-basin scale was R2 = 0.857, R2 = 0.862 (monthly) and R2 = 0.227, R2 = 0.404 (annually), respectively; for the whole basin scale was R2 = 0.902, R2 = 0.900 (monthly) and R2 = 0.507 and R2 = 0.519 (annually), respectively. The model performed acceptably, and SDC performed the best, indicating that remote sensing data can be used for SWAT model calibration. During 2009−2018, ET generally increased in the Madu River Basin (SDC results, 7.21 mm/yr), with a multiyear average value of 734.37 mm/yr. The annual ET change rate for the sub-basin was relatively low upstream and downstream. The linear correlation analysis between ET and meteorological factors shows that on the monthly scale, precipitation, solar radiation and daily maximum and minimum temperature were significantly correlated with ET; annually, solar radiation and wind speed had a moderate correlation with ET. The correlation between maximum temperature and ET is best on the monthly scale (Pearson correlation coefficient R = 0.945), which may means that the increasing ET originating from increasing temperature (global warming). However, the sub-basins near Shennongjia Nature Reserve that are in upstream have a negative ET change rate, which means that ET decreases in these sub-basins, indicating that the ‘Evaporation Paradox’ exists in these sub-basins. This study explored the potential of remote-sensing-based ET data for hydrological model calibration and provides a decision-making reference for water resource management in the Madu River Basin.
Review of Sodic Soil Reclamation with a Snapshot of Current Research Activity
Tibor TÓTH
2022, 32(6): 1099-1109.   doi: https://doi.org/10.1007/s11769-022-1310-4
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For centuries, reclamation of sodic soils has been an essential part of cropping practices in several parts of the world. Parallel to increasing population, the need for new cropland constantly re-evaluates land suitability concepts. Therefore, the importance of sodic soils as potential croplands is increasing worldwide. Although theoretically farmers can choose from a wide variety of reclamation options, according to profitability, business plans, and human and financial resources, in practice, few reclamation methods are applied at large scale. This article touches on the early history, 20th Century intensive research, and current trends of sodic soil reclamation. New approaches such as leaching, chemical amendments, addition of organic material, and biological and microbial improvements are discussed, and also brand-new approaches are reviewed. The early history is reviewed using historical books, the achievements of the last hundred years using basic technical literature, mostly books, and the current approaches of our time with fresh publications, mostly papers and two very recent conferences published in English.
Spatial-temporal Characteristics of Holocene Paleosols in the Chinese Loess Plateau and Paleoclimatic Significance
Xuelian GUO, Lusheng HE, Guoyong ZHAO, Weibin WANG, Huairen CAO, Hao WU
2022, 32(6): 1110-1118.   doi: https://doi.org/10.1007/s11769-022-1285-1
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The evolution of Holocene climate was investigated using grain size and magnetic susceptibility of the Holocene paleosols from Baicaoyuan (BCY), Xifeng (XF) and Linyou (LY) sections in the northwest, central and southern Chinese Loess Plateau (CLP). The results show that the Holocene in the BCY, XF and LY paleosol sections could be divided into three phases: during the early Holocene (11.8–10.5 kyr B. P.), increased magnetic susceptibility (χ) and frequency-dependent magnetic susceptibility (χfd) and decreased median grain size (Md) indicate that the East Asian Summer Monsoon (EASM) has become more intense and the climate has changed from cold to warm. During the middle Holocene (10.5–5.0 kyr B. P.), the values of χ, χfd and 2–5 µm grain-size fraction (GT2/5) are higher and Md and 30–63 µm grain-size fraction (GT30/63) are the lowest, which reflect a warm and humid regional climate. At ~ 8.0 kyr B. P., there was a transient dry-cold climatic spike corresponding to a Heinrich Event, the cold event was likely due to the collapse of the Laurentide ice sheet. During the late Holocene (5.0–0 kyr B. P.), χ and χfd values are the lowest, while Md and GT30/63 are high, as proxies of a weakened EASM, when the dry-cold climate prevailed in the region. Decreased irradiance since 5.0 kyr B.P. may have caused climatic cooling and drying. Spatially, the increased main peak values and skewness from BCY, XF to LY sections show that the grain size became fine, the East Asian Winter Monsoon (EAWM) reduced, and climate was warmer and wetter from northwest to southeast. In addition, Md can be used as alternative proxy for EAWM, while χfd is positive with the intensity of EASM under semiarid climate conditions in CLP.