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.
The black soil area in Northeast China serves as a “ballast” to ensure China’s food security. Unreasonable development and utilization lead to serious black soil degradation in some areas and affect regional food production and economic and social development. In the context of the intensification of the contradiction between food supply and demand worldwide, we should pay more attention to the overall situation of regional sustainable development and seek for systematic, scientific, and economic solutions. This study establishes a regional all-for-one customization model of black soil granary on the basis of the regional system of human-land relationship, customized and accurate management, agricultural system theory, and agricultural informatization with the guidance of integrated geography concept. The aim of this regional all-for-one customization model is to systematically diagnose the key problems and leading factors of black soil degradation and determine a solution that combines the commonness and individuality of black soil protection from the perspective of multiscale linkage, multifactor coupling, and multitechnology cooperation. The regional all-for-one customization model of black soil granary integrates the two perspectives of “regional” and “customization” into the protection and comprehensive utilization of black soil for the first time. It adopts zoning, grading, and classification as the main strategy and big data and artificial intelligence as the main technical approaches. This model constructs three strategies of different scales by combining the “satellite-air-ground-network” 3D monitoring system and the all-for-one customization platform driven by big data and artificial intelligence. First, the “implementing strategies by regions” are implemented at the regional scale to formulate the regional agricultural resource allocation scheme and agricultural zoning, which can provide strategies to protect and utilize black soil effectively. Second, the “determining strategies in accordance with villages” are implemented at the village scale to formulate a black soil protection and utilization model for different categories of villages, which can promote the organic integration of black soil protection and rural revitalization. Third, a “one strategy for one field” concept is applied at the field scale to provide accurate strategies for soil restoration and yield improvement in a fixed, quantitative, and regular manner. Multiscale integrated demonstration and scheme verification of the regional all-for-one customization model of black soil granary are conducted in Qiqihar City at three scales, namely, region, village, and field, to solve the key issues in black soil protection and utilization and form a replicable and popularized system solution, thereby providing a model for the sustainable development of Chinese and global black soil agriculture. The proposed regional all-for-one customization model of black soil granary has important theoretical and practical value in promoting the high-quality development of regional agriculture and rural revitalization, and provides a demonstration model of land protection and utilization for the black soil area in China and the whole world.
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.
Recent years have witnessed rapid and widespread economic growth in regions involved in China’s Belt and Road Initiative (BRI), mainly due to the construction of six economic corridors. This paper aims to quantify the levels of six economic corridors according to the socioeconomic development levels in the BRI regions. Here, a gridded socioeconomic development index was first created, and a dividing line was drawn to reveal the distribution characteristics of socioeconomic development in the BRI regions. A classification method was then applied to identify local development levels. Finally, we created an economic corridor development index (ECDI) to evaluate the progress of six economic corridors. The results reveal spatial heterogeneity within the socioeconomic groups of BRI regions, which can be roughly divided into offshore (or Part A, 50.54%) and inland (or Part B, 49.46%) areas. Although both parts comprise roughly the same area, over 95% of the population is located in offshore regions. The China-Mongolia-Russia Economic Corridor has the highest development index due to a stable political environment and long-running cooperation. The China-Pakistan Economic Corridor suffers from the lowest ECDI but with strong development potential. Our methods can provide critical reference and practice for the future evaluation of the level of regional development. The results of this study can offer policymakers some insight into reducing socioeconomic inequality in the BRI regions.
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.
Multi-source weighted-ensemble precipitation (MSWEP) is one of the most popular merged global precipitation products with long-term spanning and high spatial resolution. While various studies have acknowledged its ability to accurately estimate precipitation in terms of temporal dynamics, its performance regarding spatial pattern and extreme rainfall is overlooked. To fill this knowledge gap, the daily precipitation of two versions of MSWEP (MSWEP V2.1 & V2.2) are compared with that of three representative satellite- and reanalysis-based products, namely the Tropical Rainfall Measuring Mission (TRMM 3B42 V7), the climate prediction center morphing technique satellite-gauge merged product (CMORPH BLD), and the fifth-generation reanalysis product of the European Centre for Medium Range Weather Forecasts (ERA5). The comparison is made according to the dense daily rainfall observations from 539 rain gauges over the Huaihe River Basin in China during 2006-2015. The results show that MSWEP V2.1, MSWEP V2.2 and CMORPH BLD have better performance on temporal accuracy of precipitation estimation, followed by ERA5 and TRMM 3B42 V7. MSWEPs yield the most even spatial distribution across the basin since it takes full advantage of the multi datasets. As the weighted-ensemble method is independently carried out on each grid in MSWEPs, the spatial distribution of local precipitation is changed by different source data, which results in that MSWEPs perform worse than CMORPH BLD in terms of the representation of precipitation spatial pattern. In addition, the capability of MSWEPs to describe the spatial structure in the rainy season is lower than that in the dry season. Strong precipitation (≥100 mm/d) events are better represented in TRMM 3B42 V7 products than in MSWEPs. Finally, based on the comparison results, we suggest to improve the merging algorithm of MSWEP by considering the precipitation spatial self-correlation and adjusting the merging weights based on the performance of the source datasets under different precipitation intensities.
The stability of estuarine channel-shoal systems is important for port utilization, navigation maintenance, habitat protection and ecosystem service functions. This paper uses the South Channel of the Changjiang (Yangtze River) Estuary as a typical example to investigate the channel-shoal adjustment mechanism and its future trend. The combined approaches of bathymetric data analysis and process-based modeling (Delft3D) are applied. Quantitative analysis of morphological changes indicates that the South Channel experienced remarkable channel-shoal adjustment during 1958-2018. Periodic evolution was identified, including shoal migration, incision and emergence under natural conditions before the mid-1980s. Since then, fluvial sediment decline and local human intervention have interrupted the periodic processes. After 1986, as river sediment discharge started to decline, the South Channel converted to net erosion, and both the mid-channel shoal at the bifurcation node and the tail of the Ruifeng Shoal showed significant scour. Process-based hydrodynamic simulations revealed that the northern rotation of the mainstream downstream of Wusong triggered the erosion of the Ruifeng Shoal, while unordered sand mining at the shoal tail in approximately 2002 enhanced shoal shrinkage. In addition, the self-adjustment of the transverse section shape resulted in abnormal accretion in 2002-2007. Afterward, the South Channel underwent overall erosion as sediment discharge decreased to a low level (<150 Mt/a). Five stages of channel-shoal pattern adjustment and accretion/erosion status during the past 60 years were defined, i.e., the accretion stage (1958-1965), remarkable channel-shoal adjustment stage (1978-1986), slow erosion stage (1986-1997), shoal scour and shrinkage stage (1997-2007) and overall channel-shoal erosion stage (2007-2018). Model prediction of the evolutionary trend indicates that overall erosion within the South Channel is most likely to continue in 2015-2050. Further adjustment of the South Channel under extremely low sediment discharge may threaten the riverbed stability and the sustainable development of this large-scale estuary. Future work on adaptive strategies for varying conditions is recommended.
The energy dissipation of boundary resistance is presented in this paper based on the flow resistance. Additionally, the river morphology responses to the resistance energy dissipation are explored using the Gaocun-Taochengpu reach in the lower Yellow River as a prototype. Theoretical analysis, measured data analysis and a one-dimensional hydrodynamic model are synthetically used to calculate the energy dissipation rate and riverbed morphological change. The results show that the energy dissipation rate along the channel will increase in both the mean value and the fluctuation intensity with increasing discharge. However, the energy dissipation rate will first decrease and then increase as the flow section or width-depth ratio increases. In addition, the energy dissipation rate has a significant positive correlation with the riverbed stability index. The results imply that the water and sediment transport efficiency of the river channel can be improved by optimizing the cross-sectional configuration to fulfil the minimum energy dissipation rate of the boundary resistance under stable riverbed conditions.
General history of disasters in China suggests that China has frequently experienced two major natural disasters in its long history, one is from catastrophic earthquake events, and the other is from extreme climatic events, due to its unique active tectonic environment and climatic complexity. Although these two major natural disasters have caused great damage to human society, it remains unclear whether and how they affect Chinese dynasty alternation on decadal (emperor) timescales. Based on detailed comparisons between abrupt climatic changes, catastrophic seismic activities, and the history of Chinese dynasty alternation from 1000-2000 AD, we conclude that on decadal timescales, extreme drought (and/or flood) events could indeed significantly reduce agricultural production, cause severe food shortages and famine, and result in increases in population exile, rising food prices and inflation, and insufficient supplies for military defense, which could exceed social resilience and eventually lead to financial risks and social upheavals of the dynasties. In addition, catastrophic seismic events in the densely populated, agricultural areas of China, including the 1303 surface wave magnitude (Ms) 8.0 Hongtong earthquake, the 1556 Ms 8.25 Huaxian earthquake and the 1920 Ms 8.5 Haiyuan earthquake, caused more than 200,000 casualties and millions of victims to live in exile which was almost equivalent to the order of magnitude of those extreme climatic events-induced refugees. The secondary geological hazards related to the earthquakes (e.g., extensive landslides and soil erosion), which could last for decades, caused more casualties and reduced food production. Furthermore, great plague spread caused by the casualties could significantly increase psychological panic among the survivors, resulting in social instability. Therefore, catastrophic seismic events could also accelerate the collapse of the dynasties (e.g., the Ming dynasty) without immediate mitigation measures. This study indicates that catastrophic seismic activities, as well as extreme climatic events, could have great effects on the social structures and thus on the Chinese dynasty alternation on decadal timescales, which highlights the far-reaching implications of geological hazard research.
Central Asia (CA) is one of the most fragile regions worldwide owing to arid climate and accumulated human activities, and is a global hotspot due to gradually deteriorating ecological environment. The Amu Darya Basin (ADB), as the most economically and demographically important region in CA, is of particular concern. To determine the concentration, source and pollution status of heavy metals (HMs) in surface sediments of the ADB, 154 samples were collected and analyzed for metals across the basin. Correlation and cluster analysis, and positive matrix factorization model were implemented to understand metals’ association and apportion their possible sources. Cumulative frequency distribution and normalization methods were used to determine the geochemical baseline values (GBVs). Then, various pollution indices and ecological risk index were employed to characterize and evaluate the pollution levels and associated risks based on the GBVs. Results indicated that the mean concentrations of HMs showed the following descending order in the surface sediments of ADB: Zn > Cr > Ni > Cu > Pb > Co > Cd. The spatial distribution maps showed that Cr, Ni, and Cu had relatively high enrichment in the irrigated agricultural area; high abundances of Zn, Pb, and Cd were mainly found in the urban areas. Four source factors were identified for these metals, namely natural sources, industrial discharge, agricultural activities, and mixed source of traffic and mining activities, accounting for 33.5%, 11.4%, 34.2%, and 20.9% of the total contribution, respectively. The GBVs of Cd, Zn, Pb, Cu, Ni, Cr, and Co in the ADB were 0.27, 58.9, 14.6, 20.3, 25.8, 53.4, and 9.80 mg/kg, respectively, which were similar to the regional background values obtained from lake sediments in the bottom. In general, the assessment results revealed that surface sediments of the ADB were moderately polluted and low ecological risk by HMs.
Lunar landforms are the results of geological and geomorphic processes on the lunar surface. It is very important to identify the types of lunar landforms. Geomorphology is the scientific study of the origin and evolution of morphological landforms on planetary surfaces. Elevation and relief amplitude are the most commonly used geomorphic indices in geomorphological classification studies. Previous studies have determined the elevation classification criteria of the lunar surface. In this paper, we focus on the classification criteria of the topographic relief amplitude of the lunar surface. To estimate the optimal window for calculating the relief amplitude of the lunar surface, we use the mean change-point method based on LOLA (Lunar Orbiter Laser Altimeter) Digital Elevation Model (DEM) data and SLDEM2015 DEM data combining observations from LOLA and SELenological and Engineering Explorer Terrain Camera (SELENE TC). The classification criterion of the lunar surface relief amplitude is then determined according to the statistical analysis of basic lunar landforms. Taking the topographic relief amplitudes of 100 m, 200 m, 300 m, 700 m, 1500 m and 2500 m as thresholds, the lunar surface is divided into seven geomorphic types, including minor microrelief plains (< 100 m), minor microrelief platforms [100 m, 200 m), microrelief landforms [200 m, 300 m), small relief landforms [300 m, 700 m), medium relief landforms [700 m, 1500 m), large relief landforms [1500 m, 2500 m) and extremely large relief landforms (≥ 2500 m). The minor microrelief plains are mainly distributed in the maria and the basalt filled floors of craters and basins, while the minor microrelief platforms are mainly in the transition regions between the maria and highlands. The microrelief landforms are mainly located in regions with relatively high topography, such as wrinkle ridges and sinuous rilles in the mare. The small relief landforms are mainly scattered in the central peak and floor fractures of craters. The medium relief landforms are mainly distributed in the transition regions between crater floors and crater walls, between crater walls and crater rims, between basin floors and basin walls, and between basin walls and basin rims. Large and extremely large relief landforms are mainly found along crater walls and basin walls. The classification criteria determination for assessing lunar surface relief amplitude described in this paper can provide important references for the construction of digital lunar surface geomorphology classification schemes.
