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The Silk Road initiative is both exciting and controversial, as it may bring environmental degradation and water resources concerns, and at the same time it promotes swift economic growth in poverty-stricken areas along the Silk Road. Finding a balance between environmental protection and economic growth is the motivation for publishing this thematic issue. The Guest Editors introduce the background of the Silk Road in this editorial and the papers included in this thematic issue. These studies represent only some preliminary efforts toward establishing the harmonious relationships required to address these issues and to encourage further investigations. [ABSTRACT FROM AUTHOR]

Water plays an important role in human civilisation. Since ancient times people started to settle in regions with ensured water availability. Trade was an important factor for the development of civilisation. Silk Road is an important route used for the trading between China and other countries across Eurasia. Not only silk, many goods including leather were exchanged during trading. Leather was processing lead to release of large amount of wastewater. This study was carried out to understand how the leather processing would have affected the groundwater quality in Silk Road sites by studying the current scenarios of groundwater quality near tanning industries. Chennai and nearby cities such as Ranipet and Vaniyambadi are chosen for case studies. Groundwater quality around the tanneries was poor due to high electrical conductivity and concentration of chromium. This is due to the effluents released by the tanneries into the ground or open drains without proper treatment. Similarly, the leather processing in Silk Road sites would have also affected the groundwater quality. [ABSTRACT FROM AUTHOR]

The irrigation areas distributed on the Loess Tableland where the Silk Road begins have historically contributed greatly to the excellent agricultural civilization of China. However, increasing shortages of water resources and the resulting problems, such as the drainage of groundwater, ground fracturing and land subsidence, have emerged gradually in some parts of these irrigation areas; this has posed a large challenge to local people and water authorities in past decades. As the most essential issue for these irrigation areas, the water source, its condition and crises were analyzed by taking the Jinghuiqu Irrigation Area as an example in this paper. Considering the minimum environmental instream flow in the Jinghe River with different methods, a reasonable value of the average annual available runoff was evaluated for the Jinghuiqu Irrigation Area, and the water shortage was evaluated by considering two different types of water usage based on hydrological analysis and statistics. The results indicate that the situation is not promising as a whole. For some dry years, the available runoff is lower than the average annual water requirements of the irrigation area, and moreover, the situation will become increasingly worse if the runoff in the Jinghe River decreases continuously, which has been its tendency for the past few decades. Based on the severe groundwater situation, surface water should always be given priority in irrigation, and irrigating with groundwater should be strictly prohibited during wet periods and restricted during normal and dry years in the whole area. [ABSTRACT FROM AUTHOR]

The West Development Program, initiated in 2000 by the central government of China, has attracted huge investments in the arid and semiarid regions of northwest China. As a consequence of this development, environmental pollution and ecological degradation have been widely reported. The Silk Road economic belt proposed by China promotes further economic development in the regions, but rational planning and regular monitoring are essential to minimize any additional negative impacts of the anthropogenic activities. This article reports an investigation on the distribution, enrichment and sources of trace metals in the topsoil in and around the Ningxia Hengli Steel Wire Plant (HSWP) situated along the Silk Road economic belt. The concentrations of Cd, Pb, Cr, Cu, Zn, Ni, Mn, V and Co in the surface soils of the study area vary, respectively, in the following ranges: 0.083-18.600, 21.9-2681.0, 58.0-100.0, 14.6-169.9, 59.0-4207.3, 19.3-40.8, 411-711, 55.2-76.6 and 7.46-25.21 mg/kg. The concentrations of Cd, Pb, Cr, Cu, Zn and Co are significantly higher than their local background values. Pollution levels of these trace metals in the surface soils were assessed using contamination index (Cif), geo-accumulation index (Igeo), modified contamination degree (mCd) and pollution load index. The potential ecological risks caused by the metal pollution were assessed by means of potential ecological risk factor (Eif) and potential ecological risk index. The Spearman correlation and cluster analysis were applied to determine the contamination sources. The HSWP zone, associated with very high potential ecological risk caused by Pb and Cd, is more seriously contaminated by trace metals than the residential zone. This study indicates that Cd, Pb, Cu, Zn and Co mainly originate from industrial pollution, whereas Cr, Mn, Ni and V result from both industrial activities and natural processes. [ABSTRACT FROM AUTHOR]

The Tarim Basin is the heart of China's Silk Road Economic Belt. The contradiction between economic growth and environmental protection is particularly evident in the basin region. For the past 20 years, the groundwater has been increasingly overused, causing water tables to decline precipitously. In the past decade in particular, the total water storage (TWS) in the basin has undergone a significant decreasing trend, losing around -13 9 108 m³/year from 2002 to 2013. Prior to 1998, the normalized difference vegetation index (NDVI) of natural vegetation exhibited an increasing trend at a rate of 0.012 per decade, but from 1999 onwards, the NDVI started decreasing at a rate of 0.005 per decade. In the 2000s, the bare soil areas of the Taklamakan Desert boundaries expanded by 7.8 %. At the same time, the effects of global warming on water and ecological systems are likewise intensifying in the Tarim Basin. The increases in warming have outpaced increases in precipitation, and the negative effects of climate change on the region's vulnerable ecology have intensified. Potential changes in the usage of limited water resources may further increase the risk of desertification and deepen the area's ecological poverty. Excessive water use and over allocation, including overpumping of groundwater, are themain factors causing the loss of groundwater, the depletion of total water storage, and the overall ecological degradation, but these are being exacerbated by global warming. To address all of these issues in a holistic way, a unified management mechanism that encompasses both surface water and groundwater must be developed, and the implementation of the government plan to return farmland to natural vegetation should be speed up. [ABSTRACT FROM AUTHOR]

Wei River Basin (WRB) is the origin of the ancient and new Silk Road, and it is located in Southern Fen Wei Graben System, China. Since 1950s, hundreds of ground fissures have formed in this affluent basin, and these ground fissures have become the main geohazard in WRB. This paper used a series of geological investigations, such as site investigation, trench excavation, geological drilling and geophysical survey to understand the distribution and mechanism of formation of the ground fissures in WRB. The results are: (1) 212 ground fissures in WRB were located in Xi’an, Xianyang, Weinan city, and they have clear orientations, mainly distributed from NEE to SWW, NW to SE, and E to W. Moreover, the ground fissures are accompanied by active faults along the same directions. (2) Ground fissures in WRB can be divided into two types—some ground fissures display obvious horizontal and vertical separations on the earth surface, whereas others only display obvious horizontal separations on the earth surface. (3) Ground fissures in WRB are triggered by four factors, viz. basin structure, active fault, human activities and loess erosion. (4) The mechanism for the formation of ground fissures has also been proposed: tectonic faulting is the fundamental cause of ground fissures in the Wei River basin, and imbalances in the man-land caused by human actives accelerated the ground fissures activities. (5) Many effective measures have also been proposed to mitigate the hazards of ground fissures in WRB, such as planning, engineering measures, controlling the exploitation of groundwater and monitoring. This research will be helpful in safeguarding the sustainable development of the Silk Road economic belt. [ABSTRACT FROM AUTHOR]

The region between Xi’an and Lanzhou is the first and most important part of the so-called Silk Road in China. However, this section is highly susceptible to geohazards, including landslides, debris flows, etc., as a result of complex geological formations, steep landforms, seasonal heavy rainfall, and intensive anthropogenic activity that characterize this region. These geohazards have resulted in significant damage to the local infrastructure and economy and are becoming increasingly frequent with time. To identify the distribution of characteristics of geohazards and susceptibility zoning in this region, a frequency analysis and logistic analysis were used to study the spatial distribution of geohazards. The key factors of surface topography and geology associated with geohazards were considered, including slope gradient, height differential, profile curvature, slope aspect, and rock hardness. First, the distribution and frequency of geohazards were discussed in relation to the five factors. Second, each factor’s influence was evaluated by logistic regression and the relative importance of each of the variables was discussed. Finally, geohazard susceptibility zoning was mapped using logistic regression and geography information system tools. The results of the susceptibility zoning model were validated using the locations that had recorded geohazards in recent decades; the accuracy of the model was greater than 86.8 %. The model validation proved that there was good agreement between the susceptibility mapping and historically recorded geohazards. The logistic regression model produced acceptable results using a receiver operating characteristics curve in which the total area under the receiver operating characteristics curve was 0.879. The results of this study can assist in preliminary planning for land use, particularly with reference to construction projects in high risk areas. [ABSTRACT FROM AUTHOR]

The degradation of soil quality is a common issue in arid and semi-arid regions along the Silk Road. To provide effective measures for controlling secondary soil salinization in irrigated farmland, this article presents a research on the water balance and salt balance in the lowland of Nanshantaizi, northwest China. On the basis of the meteorological, hydrological and hydrogeological data, a 2D transient groundwater flow model was developed to analyze the response of groundwater level to various scenarios of controlling and regulating soil salinization. The results show that the shallow water depth causes strong evaporation, resulting in the accumulation of salt in the area, and is the main controlling factor of secondary soil salinization in the lowland. The effective drainage system in the lowland can efficiently reduce groundwater level and can discharge salt into the river, thus, alleviating the soil salinization in the lowland. The reduction of irrigation water requirement in the high plain as well as in the lowland can lead towards better control of soil salinization in the lowland. The canal leakage is the main source of recharge of groundwater in the lowland. However, the reduction of the canal leakage at the beginning of soil salinization regulation is not recommended, as the reduction of canal water leakage may significantly weaken the efficiency of the new drains to remove salts that have already previously accumulated in the soils of the lowland. [ABSTRACT FROM AUTHOR]

The building of the Silk Road economic belt is an exciting prospect that may bring immense economic benefits to Eurasian countries. However, intensive human activities to be induced by it may double the water crisis in central Asia, deteriorate the vulnerable environment, and accelerate energy consumption in this area. To build a new and sustainable Silk Road economic belt, advancing scientific research, reinforcing international collaboration and enhancing education are necessary steps. With careful planning, sound research, good data and the support from governments and the people, the Silk Road economic belt can be developed in an environmentally sustainable manner that is a credit to all involved. [ABSTRACT FROM AUTHOR]

The Silk Road played an important role in the economic and cultural exchanges between central China, Europe and Central Asia. A number of heritage sites with significant values still remain throughout the Gobi Desert and other desert regions in Northwest China. Most of the heritage sites composed of adobeern materials and the earthen structures have been impacted by adverse environmental conditions for thousands of years causing severe damage with only a small proportion of the structures left surviving to the present day. Analysis of the main environmental factors affecting the heritage sites such as temperature difference, wind storms, rain storms, and the freeze-thaw process and a study of the mechanism of the deterioration are the main topics presented in this paper. The authors have concluded that a Potassium-Silica solution PS invented by one of the authors has been effective in improving the intrinsic properties of heritage site earthen structures with regard to reducing the impact of environmental damage. The results of comparative tests show that samples treated by using the PS solution have performed well, particularly in protecting structures from aeolian erosion and heavy rainfall. Some findings on the effect of PS treatment on earthen structures at heritage sites are discussed in detail in the present paper. [ABSTRACT FROM AUTHOR]