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Groundwater plays a critical water resources role in arid and semi-arid areas. Quantitative evaluation of groundwater recharge is crucial in hydrogeological investigations. Under the complex hydrogeological and climatic conditions in China's arid and semi-arid regions, groundwater recharge shows significant spatio-temporal heterogeneity. Although there has been much research, including hydrochemical analysis, isotope tracing, in-situ tests and numerical simulations, accurate quantitative groundwater recharge is still a great challenge. This paper reviews the progress in research on groundwater recharge in arid and semi-arid regions of China, focusing on the principles and current applications of the main techniques, as well as the achievements in nine typical arid and semi-arid regions (Tarim Basin, Junggar Basin, Shule River Basin, Heihe River Basin, Yinchuan Plain, Badain Jaran Desert, Loess Plateau, Ordos Plateau, North China Plain). The paper reveals that the chloride mass balance method is a popular method to estimate groundwater recharge rate, whereas stable isotopes and hydrochemistry analyses, as well as the joint use of both, have been widely used in the understanding of groundwater recharge processes and mechanisms in the arid and semi-arid regions of China. Numerical modeling and remote sensing technology will become important approaches to quantify large-scale groundwater recharge. It is also suggested that various estimation methods should be used in combination, in order to improve the reliability of recharge estimates. Furthermore, this review shows that the theoretical research so far still cannot meet the needs of regional development, and the paper highlights some scientific problems that need to be further explored. [ABSTRACT FROM AUTHOR]

Henan Province is the birthplace of Chinese civilization and one of the earliest human settlements, which means that the area has an important national cultural heritage. Traditional villages are an important facet of this cultural heritage, and studying their spatiotemporal characteristics in different periods has important theoretical and practical significance for the sustainable development and protection of cultural heritage in the region. This paper takes the traditional villages of the Yellow River basin in Henan Province that were formed before 1919 as the research object. Information on the ancient river was obtained through a literature search as well as via field research, and the important tributaries of the Yellow River in different periods were mapped using ArcGIS 10.0 software. The nearest neighbor index, kernel density estimation, standard deviation ellipse and other methods were adopted to analyze the spatiotemporal characteristics of the traditional villages. The factors that influenced the evolution of traditional villages were explored in depth by combining changes in the course of the river and water conservancy projects. The results show that the formation of traditional villages along the Yellow River in Henan Province has experienced a historical track of growth, contraction, growth and prosperity and stability. The traditional villages along the Yellow River in Henan Province generally show a clustered pattern, forming a dense concentration of traditional villages in the middle reaches of the Yellow River. The center of gravity shows a migration trend from southeast to northwest. In terms of influencing factors, the spatiotemporal evolution of the relationship between villages and their distance to water is closely related to climatic fluctuations, changes in channel, water conservancy projects and social and cultural factors. This paper deepens our understanding of the relationship between traditional village evolution and watersheds by improving the consistency between village spatial distribution and historical geography and provides a useful theoretical reference for the sustainable development of China's traditional villages. [ABSTRACT FROM AUTHOR]

This paper explores whether the sponge city construction implemented in China can restore the hydrological condition of the river basins through runoff depth. The annual runoff depth was calculated based on the volume capture ratio of annual rainfall (VCRAR) and compared with undeveloped and before sponge city construction. The results conclude as follows: the current rainwater source control standard benefits the hydrology recovery in China. But the difference between before sponge city construction and undeveloped is large in 12.9% of the regions. The adjustment recommendations of the VCRAR proposed in this paper are favourable to restoring the river basin hydrology. [ABSTRACT FROM AUTHOR]

For mankind's survival and development, water, energy, and food (WEF) are essential material guarantees. In China, however, the spatial distribution of WEF is seriously unbalanced and mismatched. Here, a collaborative governance mechanism that aims at nexus security needs to be urgently established. In this paper, the Yellow River Basin in China with a representative WEF system, was selected as a case. Firstly, a comprehensive framework for WEF coupling coordination was constructed, and the relationship and mechanism between them were analyzed theoretically. Then, we investigated the spatiotemporal characteristics and driving mechanisms of the coupling coordination degree (CCD) with a composite evaluation method, coupling coordination degree model, spatial statistical analysis, and multiscale geographic weighted regression. Finally, policy implications were discussed to promote the coordinated development of the WEF system. The results showed that: 1) WEF subsystems showed a significant imbalance of spatial pattern and diversity in temporal changes; 2) the CCD for the WEF system varied little and remained at moderate coordination. Areas with moderate coordination have increased, while areas with superior coordination and mild disorder have decreased. In addition, the spatial clustering phenomenon of the CCD was significant and showed obvious characteristics of polarization; and 3) the action of each factor is self-differentiated and regionally variable. For different factors, GDP per capita was of particular importance, which contributed most to the regional development's coupling coordination. For different regions, GDP per capita, average yearly precipitation, population density, and urbanization rate exhibited differences in geographical gradients in an east-west direction. The conclusion can provide references for regional resource allocation and sustainable development by enhancing WEF system utilization efficiency. [ABSTRACT FROM AUTHOR]

[Display omitted] • The drought pattern in China is closely related to the basin distribution and multiple teleconnection factors. • The intensity and frequency of drought in China exhibited an increasing trend. • The ENSO-AO had important positive effects in the major basins in China. • Multiple wavelet coherence helps identify the processes controlling drought changes. Due to increasing global warming and the frequent occurrence of severe drought risk in recent decades, many studies have investigated drought in China. However, the spatiotemporal heterogeneities of droughts are complicated, and a comprehensive analysis of the driving forces has not been thoroughly explored. In this paper, we studied the temporal and spatial patterns of drought in China from 1960 to 2018 and disclosed its relationship with multiple teleconnection factors on different time scales. The results show that (1) Drought in China has exhibited a fluctuating increasing trend over the past 59 years, with a standardized precipitation–evapotranspiration index (SPEI) rate of change of –0.12/10 a, and the most severe droughts occurred during 2000–2010. (2) There was a significant abrupt change in China's meteorological droughts induced by climate change around 1997. (3) The trend in China was characterized by drought in spring and autumn and humidification in winter, while the trend in the Southwest River Basin was characterized by drought. (4) A combination of factors can best explain the drought variations from basin to basin, and the El Niño-Southern Oscillation (ENSO)-Arctic Oscillation (AO) was most commonly the best predictor. The use of multiple wavelet coherence helps to identify the dominant drought change processes. [ABSTRACT FROM AUTHOR]

This study investigates shared benefits through the cooperation between North Korea and China over transboundary water management in the Yalu River Basin. Primary attention has been placed on joint hydropower development since the 1950s, which has brought in developmental benefits for North Korea and security benefits for China. Data on the study have been collected from relevant papers, government publications, and media reports of China and South Korea. The information on North Korea, particularly about hydropower dams, is only accessible through secondary sources collected from South Korean government thinktanks due to the lack of publicly available data. The case study method is deployed for exploring specific issues and context and addressing problems. The significance of the study lies in the fact that this study is one of the first studies to examine transboundary river cooperation for development and security benefits between the countries. An array of bilateral agreements over the river basin has culminated in co‐building and jointly operating the four dams along the river. The construction of two additional dams, which is nearing completion, symbolizes shared benefits for both countries, hydroelectricity for North Korea, and regional security for China. Research Impact Statement: The study provides an in‐depth and unique analysis of joint hydropower development between North Korea and China in the Yalu River Basin. [ABSTRACT FROM AUTHOR]

The assessment of the accessibility for medical resources is of great significance for understanding the distribution characteristics and optimizing the space allocation of medical resources. This paper incorporated the probability statistical data of actual medical treatment choice behavior of residents into the formulation of accessibility. We constructed a health facility accessibility index combined the travel time with waiting time and an improved three-step floating catchment area method to evaluate the accessibility of outpatient and inpatient treatment for residents. Results showed the accessibility of outpatient and inpatient treatment has significant geographical differentiation characteristics and presents a distribution pattern of high in the eastern and central China and low in the western. The outpatient medical service was available for residents, which there are more than 85% of the population having access to medical services within 30min.The accessibility of inpatient treatment presents a radiological distribution model with provincial capital city as the core, in which the spatial allocation of high-quality medical resources is not balanced and the regional difference is obvious. This study demonstrated the geographical differentiation characteristics of spatial distribution for the accessibility of medical resources in China, which can provide targeted proposals according to medical institutions level. • Evaluating the spatial accessibility from outpatient and inpatient medical treatment. • A health facility accessibility index and the improved three-step floating catchment area method were employed. • The policy-oriented matrix of medical services was constructed to provide policy recommendations for the provinces in China. [ABSTRACT FROM AUTHOR]

In this paper we use archaeometallurgical data from the Yunnanese Bronze Age sites of Hebosuo and Shangxihi, to examine the nature of early exchange networks within Yunnan, across southern China and into Mainland Southeast Asia (MSEA). Traditional perspectives on relations between China and MSEA were viewed from a Core-Periphery (C–P) perspective, derived from World Systems Theory (WST) but this area, though now divided by national borders, has shared ecological and cultural characteristics that allow its definition as the Southeast Asian Massif (SAM). The fourteen analysed samples were all unleaded copper or bronze, mostly as-cast and with some annealing. Their lead isotope signatures did not group at site level but showed broad consistency with the other, limited, signatures available from Yunnan, Sichuan and Guangxi. Critically, comparison with MSEA signatures revealed good isotopic consistency with key Bronze Age sites in Thailand, Myanmar and Vietnam, active within tight timeframes, and mostly lying on or near the path of major river systems that find their source in or via Yunnan. The picture we propose, based on current data, is one of a complex network of autochthonous SAM societies interacting at short (ca. 50 km), medium (ca. 300 km) and long (ca. 800–1600 km) ranges over mountainous and forested terrain. • Yunnan and Mainland Southeast Asia have recently aligned Bronze Age chronologies. • 14 copper-base artefacts from early 1st mill. BC Hebosuo and Shangxihi were analysed. • 8 were unleaded copper and 6 were unleaded copper.11 as-cast, 2 annealed & 1 corroded. • Lead isotope ratios did not cluster intrasite but were consistent with southern China. • Consistency with selected Mainland Southeast Asian signatures suggests radial network. [ABSTRACT FROM AUTHOR]

[Display omitted] • Accurate assessment of China's ecological environment changes in the past 20 years is important. • We used time-series NDVI data (1998–2018) to evaluate China's ecological environment change. • In one-third of China the ecological environment has improved, and in 10%, the ecological environment has deteriorated. • The Yellow River Basin is an area where the ecological environment has significantly improved. • The main reason for the deterioration in the ecological environment of the eastern coastal areas is urban expansion. The ecological environment is the foundation of human survival and development. China's ecological environment has undergone a historic transition from partial improvement to overall improvement. In this paper, long time series NDVI data (1998–2018) are used to evaluate the ecological environment change and spatiotemporal change that has taken place in China over the last 20 years, at different scales (regional, provincial, county, and grid scales). Combined with typical areas, the causes of ecological environment change are revealed. The results show that in about one-third of China, the ecological environment improved, and in 10%, the ecological environment deteriorated. Ningxia, Shaanxi, Shanxi, Guizhou, and Guangxi are the provinces in which the improvement of the ecological environment is most pronounced. However, the ecological environments with vegetation as the core in Shanghai and Jiangsu Province have deteriorated significantly. The areas with the fastest improvement in their ecological environment are those with precipitation of 200–600 mm. The Yellow River Basin is an area where the ecological environment has significantly improved. Forestry projects and the development of oasis agriculture effectively promote the improvement of the ecological environment. In the past 20 years, the main reason for the degradation of the ecological environment in eastern coastal areas is urban expansion. China should continue to strengthen its overall layout of forestry projects and improve its ecological environment. When planning its ecological construction, China should fully consider the associated physical and geographical conditions, and adjust measures to local conditions accordingly. China should coordinate the relationship between development and protection and avoid the "pie spread" expansion witnessed in eastern coastal areas. [ABSTRACT FROM AUTHOR]