Orginal Article

Water resource formation and conversion and water security in arid region of Northwest China

  • CHEN Yaning , 1 ,
  • LI Baofu 1, 2 ,
  • LI Zhi 1 ,
  • LI Weihong 1
  • 1. State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, CAS, Urumqi 830011, China
  • 2. College of Geography and Tourism, Qufu Normal University, Rizhao 276826, Shandong, China

Author: Chen Yaning (1958-), Professor, specialized in studies on water resources and surface processes in arid regions. E-mail:

Received date: 2016-04-25

  Accepted date: 2016-05-10

  Online published: 2016-07-25

Supported by

National Natural Science Foundation of China, No.41471030, No.41501211


Journal of Geographical Sciences, All Rights Reserved


Climate change and water resource issues are global problems of common concern to the international community, and they are major bottlenecks affecting the eco-environment and sustainable socio-economic development in the arid region of Northwest China. On the basis of results from previous studies, this paper points out that the unique landscape of Northwest China increases the complexity and uncertainty of the climate system. This paper analyzes the key constraints on socio-economic development and ecological security in the region, discusses the impact of climate change on water resources in Northwest China, identifies common themes and the main problems present in research on climate change and water resources in the arid northwest region, and finally, based on the importance and urgency of conducting research on the region’s water resources, proposes scientific problems that need to be addressed: first, the impact of climate change on the formation, conversion and future trends of water resources in the region; second, bidirectional coupling of high-resolution regional climate models and water cycle models of arid region land surface patterns; third, the impact of climate change and human activities on water resources of the arid northwest region. Through consideration and discussion of the above, this paper seeks to further clarify specific areas of research on pressing issues related to climate change and water resources in Northwest China, so as to establish a solid scientific basis for significantly enhancing our ability to respond to climate change and water shortages.

Cite this article

CHEN Yaning , LI Baofu , LI Zhi , LI Weihong . Water resource formation and conversion and water security in arid region of Northwest China[J]. Journal of Geographical Sciences, 2016 , 26(7) : 939 -952 . DOI: 10.1007/s11442-016-1308-x

1 The issues

Global climate change is an important issue of common concern to the international community today. Climate change issues and the measures required to respond to climate change involve all aspects of the natural ecosystem and human life and production, and they have become major issues in contemporary human society that need to be resolved. The arid region of Northwest China is a mid-latitude zone in the hinterland of the Eurasian landmass and an area sensitive to global climate change. In the past half century, the temperature of the arid northwest region has increased at a rate of 0.33-0.39°C/10a (Zhang et al., 2010; Li et al., 2012), higher than the rest of China (0.25°C/10a) (Ren et al., 2005) and the global average (0.14°C/10a) (IPCC, 2013). In the arid northwest region, water resources are a key factor restricting socio-economic development and affecting ecological security, and they play a vital role in achieving sustainable socio-economic development in the future (Chen et al., 2016). Against the background of global warming, the arid northwest region, which relies on mountain precipitation and glacial meltwater as the basis of its water resource system, is extremely fragile, which is reflected by the marked increase in hydrological events (Sun et al., 2014), greater uncertainty over water resources and changes in the traditional rules governing the water cycle and eco-water demand. As the population rises and demand for water for socio-economic development increases further, the water resource issues facing the arid northwest region are set to worsen and their impact will deepen. At the same time, Northwest China is the source of a number of major international rivers, and instability of water resources caused by climate change has led to increased tensions between Central Asian countries. This constant conflict over water and the impact of climate change on the hydrological cycle are becoming focal points of international concern.

1.1 Mountain and basin landform causing complexity and uncertainty in climate

The arid northwest region of China is characterized by basins and high mountains. The climate is deeply affected by the role of plateau uplift, westerly circulation and the East Asian monsoon, which creates a unique climate system made up of three basic geographical units, namely mountains, oases and deserts, and produces material migration and energy conversion processes mainly driven by water. The arid northwest region is vast, with complex regional topography and diverse ecosystems, including the lofty Tianshan, Altay, Kunlun and Qilian mountain ranges and the Gobi Desert. Unlike low-latitude subtropical arid zones, the unique arid northwest region is located at relatively humid latitudes, giving it a special and complex climate system. Research has shown that for almost 50 years the mountains, oases and deserts of Northwest China have experienced different changes in climate. This is mainly shown by differences in the speed of change in temperature and precipitation and in the timings of climatic jumps (Li B F et al., 2013). Similarly, even within the same ecosystem there are significant regional differences in climate change. For example, due to the tall barriers created by the terrain, the northern and southern slopes of the Tianshan Mountains have experienced differences in climate change (Wang et al., 2015).
The northwest region is also vulnerable to the impacts of global warming and human activities, and its climate system is unstable and extremely sensitive to global climate change. In recent 50 years, as the Earth’s climate has warmed, temperatures have increased in the arid northwest region at a rate twice or three times, higher than the world average. As average levels of precipitation have fallen slightly in China, the northwest region’s precipitation variability has increased, with a rise in precipitation overall. These unique changes in climate factors are closely linked to fluctuations in the Siberian High, Western Pacific Subtropical High, North American Subtropical High, Qinghai-Tibet Plateau Circulation and other atmospheric pressure systems (Li et al., 2012; Chen et al., 2014a; Li et al., 2016a), which are themselves inextricably linked to human activity. On the other hand, many scholars believe that the climate of the arid northwest region is becoming hotter and more humid, but temperatures over the past decade have fluctuated considerably while precipitation has decreased slightly, and it is unclear whether this indicates that the climate is becoming warmer and drier or warmer and more humid. On the whole, the climate of the arid northwest region is complex and characterized by considerable uncertainty.

1.2 Water resources as a crucial factor restricting socio-economic development and ecological security

The northwest region suffers from severe water shortages in the whole of China. The region covers an area of 2.5 million km2, has average annual precipitation of 230 mm and has evaporation capacity of 8-10 times its precipitation level. It has approximately 110.9 billion m3 of water, or roughly 5% of China’s total, and it has only 4.4x104 m3/km2 of groundwater, meaning it has a water shortage (Chen, 2014). Changes to water resources caused by climate change, whether in terms of quantity or spatio-temporal distribution, will result in greater conflict over the exploitation and utilization of water resources for striking a balance between maintaining the eco-environment and pursuing economic growth in the northwest region.
The shortage of water resources in the arid northwest region and the heterogeneity of their spatio-temporal distribution mean that the region’s ecosystems are fragile. The majority of the ecological issues in arid areas are the result of an imbalance in water and salt levels caused by human activities. Northwest China is dominated by mountains and the Gobi Desert, with less than 10% of land area consisting of oases, with belts found along rivers and patches found in the wilderness surrounded by desert. Arid regions are often characterized by relatively abundant natural resources and an extremely fragile eco-environment, and the conflict between environmental protection and reconstruction and economic development in the course of exploiting water resources is always the core problem in water resource management in arid regions. Within the context of global warming, as population pressure increases and unsuitable land and water development activities continue, ecological and economic issues in the course of exploiting water resources will become increasingly acute in arid regions, and changes in the amounts and spatio-temporal distribution of water caused by climate change will possibly lead to greater conflict over supply and demand of water resources among oasis economies and desert ecosystems within river basins, leading to difficulties such as coordinating use of surface water and groundwater between oases and desert areas as conversion periods become less predictable. In terms of allocation of water resources, there is no clear method for scientifically allocating water for eco-water demand and water used in production within river basins, which threatens ecosystems and ecological security, so ecological and environmental issues caused by water are becoming increasingly prominent. The over-exploitation of water during the past three decades has caused desert vegetation to recede and damage to ecosystems. The eastern part of the lake at the mouth of the Heihe River and the western part of Juyanhai Lake have dried up; desertification is increasing, and the region has become a source of sandstorms; the water table has dropped significantly in the Shiyang River area, leading to deterioration in the eco-environment; and the 321-km long lower course of the Tarim River has dried up. The drying up of rivers has caused shrinkage and the disappearance of oases in their lower courses, leaving behind a series of ecological problems, including saline and alkaline soil, sandstorms and ecological refugees.

1.3 Climate change intensifying water resource uncertainty

The arid northwest region has extremely distinct characteristics of water resource formation and conversion, water cycle process and spatio-temporal distribution, which are representative of those found in arid regions around the world. Water resources in Northwest China all come from mountain precipitation and snowmelt, sources that are particularly sensitive to global climate change and which are subject to considerable uncertainty. Water formation in mountainous areas comes from high mountain snow and glacial meltwater, mid-mountain forest precipitation and low mountain bedrock fissure water. However, climate change has led to uncertainty regarding the processes of growth and decline of mountain glaciers and snow cover and spatio-temporal changes in precipitation, which means future water resource trends under climate change are unclear. Oases and deserts in flat plains are deprived of water, with different sources from water and land. Oases and desert ecosystems are affected by hydrological processes. The size of oases is determined by the volume of runoff from melting snow and glaciers and precipitation, and they are very sensitive to changes in hydrological processes and water conditions. Studies have shown that future climate change will lead to greater disparity between water resources and spatial distribution of productivity, which will intensify competition over water between ecological and economic uses (Chen et al., 2015).
The Fourth Assessment Report published by Working Group I of the IPCC stated that one of the most obvious results of climate change is a change to water cycles and corresponding changes to the runoff coefficient (IPCC, 2007). Particularly in the arid northwest region, various aspects of the water cycle have been significantly influenced by land surface patterns and climate. Water resources are complex, and there is considerable elasticity in runoff and water resources. Even relatively small changes in precipitation and temperature caused by climate change can cause significant changes in runoff and have a significant impact on eco-hydrological processes in arid areas. Changes to water cycles of mountainous areas caused by climate change exacerbate the instability of the water system. As such, the response of water resources and future trends in arid regions under climate change, as well as watershed surface water and groundwater water cycle processes and mechanisms, have become international focal points. There is, therefore, a need for systematic research of the effects of climate change on the water resources of the arid northwest region of China and scientific analysis of the water cycle of this unique region in order to improve our ability to respond to future climate change.

2 Popular issues

The water cycle systems of inland river basins in the arid northwest region of China are characterized by large differences in spatio-temporal distribution, complex and diverse runoff formations and conversions, and fragile water systems. Issues such as the effects of global climate change on future water supply and use structures and coordinated development of water, ecology and economy are core issues for water resource research and regulation in the northwest region.

2.1 Water vapor sources and changing laws of the climate

Terrain greatly influences the transfer of water vapor. Water vapor is the material basis of precipitation, and there is a close correlation between precipitation and external water vapor transfer and convergence. There is, therefore, a need to study the changing laws and mechanisms of climate and hydrological factors under the weak water vapor convergence conditions of the arid northwest region, with a focus on analysis of water vapor transfer and sources. Previous research (Lin and Zheng, 1997; Zhou, 2002; Dai et al., 2006) has shown that westerly weather systems and polar ice ocean systems are the main sources of water vapor transfer to northern and southern Xinjiang in China’s northwest region, and in addition, the Hexi Corridor in the eastern section of Northwest China is also influenced by subtropical weather systems such as the East Asian monsoon and the southwest monsoons (Huan et al., 2015). The latest research (Li et al., 2016a) shows that when the North American Subtropical High and the Western Pacific Subtropical High are particularly strong, the Indian-Burma Trough deepens. Thus, southern airflow from across the equator, western airflow from the Indian Ocean and eastern airflow from the southern part of the Western Pacific Subtropical High converge to form southwest and southeast flows, respectively. These two airflows together supply a warm, moist airflow to the arid northwest region, which leads to more precipitation, or conversely, to less precipitation. It can be seen, then, that change in the strength of these atmospheric pressure systems and in the relationship between them determines the degree of water vapor transfer to the arid northwestern region and the spatio-temporal distribution of precipitation there, and it quantitatively determines the size of contribution to the arid region made by each water vapor path. This is extremely important for studying the changing law of precipitation and the frequency and intensity of extreme hydrological events.

2.2 Glacier melt and glacial water changing trends

The glacial melt inflection point occurrence time and the process and intensity of its effects on water resources in the arid northwest region are an important hot spot in the discussion of future water resource trends in the endorheic drainage basins of the region. Mountain glacial meltwater and precipitation are the main sources of many of the rivers in the northwest region, but glaciers are extremely sensitive to climate change, so the biggest impact of climate change on water resources is the effect it has on headwater glacial ice and snow reserves, which affects volumes of river runoff (Ma et al., 2010). As temperatures and precipitation have been increasingly affected by global warming in the 20th century, the majority of the glaciers around the world have retreated significantly, with a particularly rapid retreat taking place in the last 20 years (Wang et al., 2011). This change magnitude was completely unexpected and difficult to explain and predict using existing models. As a result, it is extremely urgent that we begin the search for new theories and methods for predicting changes in glacial runoff and the impact on future water resources. As the global climate changes and temperature rise, glacial meltwater will increase, meaning runoff from rivers that depend on meltwater will also increase. But the large number of small glaciers located at lower elevations will disappear first as temperatures rise, and the supply of glacial meltwater to rivers will sharply decrease as glacier reserves decrease (Chen et al., 2014b).
Almost all the rivers in the arid northwest region originate in the mountains, and more than 85% of water resources are formed in high mountains surrounding basins, so glacial (and snow) meltwater and mountain precipitation are the main sources of water for inland rivers (Chen, 2014; Chen et al., 2015). Studies have shown that the arid northwest region is extremely sensitive to climate change. For example, between 1989 and 2012, the area of a glacier in the Karatal river basin in the western Tianshan Mountains shrank from 142.8 km2 to 109.3 km2, with a mean annual retreat rate of 1.02%, which was much higher than other areas of the Tianshan Mountains (Kaldybayev et al., 2015). Another basic feature of inland river water resources in arid regions is that changes in ice and snow meltwater runoff are significantly restricted by temperature conditions of glacial areas (Deng et al., 2015), which is an issue in need of attention in studies on future glacier and water resource change.

2.3 Impact of climate change on water cycle process

Changes to the laws and mechanisms of the water cycle in the arid northwest region and the response processes they reveal are hot topics and key issues in research on regional climate change. In the past 50 years, a turning point of in the potential evapotranspiration trend occurred in 1993 in the arid northwest region, as the previous significant decline turned into a significant upward trend (Li Z et al., 2013; 2014). Research on the water cycle processes of the northwest region and responses to climate change tend to take mountain climate-hydrological processes, oasis farmland-hydrological processes and desert ecosystems-hydrological processes, as the major content, with river basin ecosystem hydrological processes constituting the main thread of research. Climate hydrological processes are non-linear complex systems with both definite and random features. The response of hydrological processes to climate change should possess multi-time and multi-space scale effect (Xu et al., 2014). In terms of time, a combination of non-linear approaches is needed to reveal the impact of climate change on hydrological processes in intra-annual, interannual, interdecadal and multi-interdecadal scales (Xu et al., 2014; Li et al., 2015). In terms of space, it is necessary to look at the relationship between climate change and mountain hydrological systems, agricultural systems of oases, groundwater in desert areas and vegetation systems, while integrating the unique features of water cycle processes, and to analyze the coupling relationship of mountains-oases-deserts and the spatio-temporal change characteristics in water cycle elements; consider regional differences in water cycle elements of river basins; identify the key factors that influence changes in water cycle elements of river basins; and interpret dynamic processes of inland river basin water cycles and the relationships between their various elements. Simulations of water cycle processes are an important direction being taken in contemporary water cycle studies, but there have been few studies on water cycles of the arid northwest region in China. Despite studies having been conducted on the atmosphere, surface water, groundwater and soil water processes of river basin water cycles, scale conversion and interface coupling difficulties mean that there have been relatively few studies on water cycle systems of river basins. There is a disconnect between basic research on water cycles and applied research on water resources, with a relative focus on macro water cycle processes in the arid northwest region and a lack of studies on the conversion relationship between water resource amounts and micro water cycle processes of ecosystems. There is a particular lack of in-depth studies for inland river basins in the arid northwest region on conversion mechanisms from mountain glacial and snow meltwater, mountain forest precipitation and surface water to groundwater, soil water and plant water, as well as quantitative laws.

2.4 Water system vulnerability and the water security threshold

The fundamental issue in water resource security is balancing supply and demand. The focus of research on water security in inland river basins of the arid regions is the intrinsic link between water from mountainous areas and the water required for living and production and by the ecosystem, as well as the dependency relationship within a river basin system between the volume of usable water and the volume of available water. Hydrological and water resource responses and vulnerability to global climate change have become important areas of research for the IPCC and other international organizations, including the AIACC project group, and research institutes (Leary et al., 2008).
Global climate change has exacerbated the conflict between water demand and supply in the arid northwest region, which has thrown into sharper relief issues such as the region’s water supply and demand imbalance, increased variability in annual runoff, more extreme hydrological events and conflict between ecological and production water uses in the process of developing water resources. As far as research on water resource vulnerability is concerned, the majority of current studies in China focus on index systems for assessing water resource vulnerability, but do not include numerous factors, including changes in water resource supply, demand and management, in evaluation systems (Tang et al., 2000; Yin et al., 2008). Due to the complexity and non-linear nature of the systems, and a lack of theoretical research on identifying the factors of vulnerability key processes and its interaction, most studies only consider linear relationships and carry out quantitative vulnerability assessments of corresponding variables, resulting in considerable uncertainty over assessment results on resource vulnerability caused by climate change (Patt et al., 2005), and incomparability of established index systems (Polsky et al., 2007). There have been particularly few studies on vulnerability to abrupt climate change (Arnell et al., 2005). Introduction of the concept of key vulnerability and identification and selection of key vulnerability criteria in a report by the IPCC in 2007 provided an important basis for guiding future scientific assessments on the vulnerability of water resources to global climate change (IPCC, 2007). The influence of climate change on the vulnerability of water systems in the arid northwest region and determining water resource security thresholds under different scenarios are focal points for scholars now and for some time to come.

2.5 Water resource allocation

Assessing the impact of climate change on the processes and intensity of future water use for production, domestic water use and eco-water consumption is a core issue in determining water allocation in the complex “water-ecology-social economy” system of the arid northwest region (Chen, 2014). As global warming and population pressure increase, the conflict between water for production, living and the eco-environment will intensify. As glaciers melt even more as temperatures rise and precipitation in mountainous areas increases, the runoff from rivers that originate in the mountains and are fed by ice and snow meltwater will remain at a relatively high level for a certain period; however, as glaciers retreat even more, water reserves dwindle rapidly and glacial melt reaches an inflection point, available surface water resources from smaller glacial rivers will decrease suddenly, or suddenly increase due to abnormal rainfall variability. At the same time, higher temperatures may lead to greater water pollution problems (Mimikou et al., 2000; Patz, 2001), with water pollution exacerbating water resource tensions, intensifying the conflict between “water-ecology-social economy” in the arid northwest region. The pattern of the ecological and social landscape in the northwest region is determined by the spatio-temporal distribution of water resources, and the spatio-temporal distribution of volumes of water determines spatial configuration and functional zoning of ecosystems and socio-economic systems. In the past 50 years, economic development activities have significantly increased the area of artificial oases in the northwest region, and a trend for socio-economic focal points to move to the middle- and upper-reaches of rivers has emerged, resulting in the shrinkage of downstream lakes and rapid deterioration of desert riparian forest ecosystems (Li et al., 2015; Li Z et al., 2016).
“Water-ecology-social economy” issues arising in the course of developing water resources in the arid Northwest China are related to many natural and social factors. However, in previous studies, there has been a disconnect between research on natural factors and that on social factors, and there is a lack of overall consideration given to different scales of water use for socio-economic development and ecosystem water demand, as well as a lack of research on the link between water resource socio-economic service functions and ecosystem service functions in arid areas. There is a need to integrate the factors of “water-ecology-social economy” into one giant complex system, in order to comprehensively study the evolution of water cycle systems and the interactive relationship between socio-economic and eco-environmental systems; to analyze the impact of climate change on the processes and intensity of future water use for production, domestic water use and eco-water consumption; to reveal the evolving water resource laws due to climate change and the influence of human activities and the interactions between water and land use/cover change and socio-economic development (Nian et al., 2014); to scientifically assess changing water resource vulnerability under different climate change scenarios; to propose rational water resource allocation thresholds to ensure the sustainable development of ecosystems and the socio- economic system; and to adjust existing water utilization structures in view of future climate change, so as to mitigate future water vulnerabilities to climate change and reduce losses caused by climate change.

3 Difficult issues

The diversity of water resources, uniqueness of water cycle processes and complexity of ecological and economic processes in the development and utilization of water resources in the arid northwest region mean it is important and urgent to conduct water resource research in the region. In-depth research is required in the following three areas.

3.1 Impact of climate change on the formation, conversion and future trends of water resources in arid areas

Climate change increases the variability and uncertainty of rivers in the arid northwest region, which are mainly supplied by ice and snow meltwater. As a result, the formation, conversion and future trends of water resources in the region all need to be analyzed along with the features, laws and trends of past, present and future climate change, starting with changes in climate factors that affect water resources and combining global changes. Using historical data, proxy data and regional climate models, the changing spatio-temporal features of climate and hydrological factors of inland river basins in the northwest region can be analyzed, the sequence of changes over a long time period can be discovered and analyzed, and future trends can be scientifically forecast. Historical hydro-meteorological data and remote sensing data should be used and a data assimilation method employed to establish a multi-scale hydro-meteorological data series, allowing investigation of changing laws, mechanisms and responses to climate change in climate and hydrological factors under weak convergence of water vapor in the arid northwest region, and analysis of the changing laws of, and statistical relationship between, temperature, precipitation, snow cover, runoff and evaporation under different temporal and spatial scales. A multi-scale, multi-method observational approach should be adopted, with environmental isotope and other environmental tracer techniques introduced (Sun et al., 2016), to establish a runoff division numerical model that can precisely divide the runoff elements of ice and snow meltwater from high mountains, precipitation from mid-mountain forests and bedrock fissure water (Fan et al., 2014); to investigate runoff formation, conversion mechanisms and water cycle processes; to analyze spatial differentiation characteristics; to quantitatively analyze quantitative conversion relations of high-mountain meltwater, mid-mountain forest precipitation and precipitation/meltwater-runoff/infiltration; and to analyze the root causes and mechanisms behind the formation of regional differences in water resources and their responses to climate change. There is also a need to combine future climate change scenarios, develop distributed hydrological models suited to mountains, oases and deserts of inland river basins, interpret the formation and conversion processes of water resources, quantitatively describe the relationship between the various components that form water resources at the river basin scale, and estimate the impact and future trends of climate change on water resources.

3.2 Bi-directional coupling of high-resolution regional climate models and water cycle models of arid region land surface patterns

The effect of climate change on societies, economies and eco-environment is an area of common concern among the international community. In order to positively respond to the challenges to human survival posed by climate change, scholars and government departments have begun researching attributes, effects and models of global climate change (Crowley, 2000; IPCC, 2013; Sun et al., 2010). Although the IPCC Fifth Assessment Report stated that important improvements had already been made in many aspects of climate model simulations of temperature and precipitation since the previous assessment report in 2007 (IPCC, 2013), the complexity and diversity of regional environments and atmospheric pressure systems mean that inevitable difficulties and drawbacks exist when it comes to study climate change on a global scale, and it is hard to give accurate descriptions and predictions of the hydrological processes of a region or a river basin using models of global atmosphere and water cycles. There are significant differences in the results of global climate models that attempt to simulate regional atmospheric changes (Jiang et al., 2010; Zhang et al., 2011), and simulation results are not fully applicable to the study of regional climate change. When using global models to analyze regional climate change they need to be adjusted for regional climate conditions. Global climate models need to be regionalized or regional climate models established (Ju et al., 2006; Li et al., 2009). Moreover, although the theoretical frameworks of atmospheric circulation models are largely similar, there are differences in their boundary settings and spatial resolutions, which often leads to uncertainties in their output results (IPCC, 2013), making it difficult to use them as basic data for regional and river basin hydrological models. Nor can they sufficiently describe regional climate features and calculated runoff processes (Boone et al., 2004), not to mention accurately reflect the actual dramatic change in climate factors in runoff areas and dissipation areas of river basins in the arid northwest region (Fang et al., 2015). Hydrologists and water resource managers are increasingly starting to focus on constructing regional climate models and studies on climate change (Montes-Hugo et al., 2009; Roy et al., 2011). The focus is on the effects of climate change on water cycle processes of river basins and regions, in the hope of obtaining relatively accurate hydrological parameters at relatively large scale spatial resolutions. However, because there is almost no river basin- or regional-scale data to directly estimate hydrological parameters, current river basin or regional water cycle models are obtained by adapting hydrological parameters to river basins or regions, or by extrapolating from information on physical attributes for regions with no data. Thus, hydrological simulations for river basins and areas in mountainous parts of the arid northwest region that do not have hydrological station data are a key and prominent scientific challenge in current hydrological studies. Although it is possible to use a modified Delta method to create a climatic reconstruction of meteorological data for high mountainous areas on the basis of the principle of similarity (Xue et al., 2015), considerable uncertainty regarding runoff simulations still exists. Thus, in order to accurately analyze regional climate change issues, it is necessary to clarify the interactive roles and mechanisms of regional atmospheric pressure systems and their effect on regional climate (Sanchez et al., 2011; Mahlstein et al., 2010). As such, it is particularly important to develop and apply research on regional climate models in order to correctly interpret regional climate change processes and future trends, rationally assess regional climate change impacts and accurately formulate strategies for responding to climate change. This is also the future trend in climate model development.
The arid northwest region’s unique geographical location and topography mean that the formation and distribution of its water resources, as well as its water cycle processes, are different from China’s eastern and other regions. At the same time, the influences of climate change and human activities on the water cycle in the region have been particularly noticeable, and there is no other region in the world with similar circulatory characteristics or water cycle processes as Northwest China; nor is there a region that can provide the northwest region with a mature example of how to develop its water resources. Because water production processes in the arid northwest region are largely concentrated in cold mountainous areas, where there are few meteorological and hydrological stations or, such stations are located in areas of lower altitude, if there are any, and the ground is frozen for much of the year in those areas, it is currently difficult for hydrological models to reflect the impact of frozen ground on runoff processes in mountainous runoff producing areas, which means simulation results are often less than perfect (Zhang et al., 2016). In addition, in the multi-objective calibration process for a distributed hydrological model, because there may be inconsistencies between objective functions, multi-objective optimization issues have become a hot topic in current hydrological studies (Yang et al., 2014). To this end, there is an urgent need to create a high-resolution arid area regional climate model based on a mountains-oases-deserts land pattern that integrates the features of the arid northwest region to investigate the control and influence the mountain and basin alternating landform and unique land surface patterns have on regional circulation. At the same time, it is necessary to consider comprehensively runoff production and dissipation, mountains and plains, and deserts and oases when producing land surface parameterization improvement programs; to develop a multi-scale and multi-objective hydrological model merging method; to construct a mountains-oases-deserts coupling, distributed regional water cycle model with land pattern features that fit arid areas and a river basin hydrological and water resource model based on mountain meltwater and precipitation. This allows quantitative identification of the impact of climate change and human activities on the water resource systems of arid areas (Li et al., 2016b; Shi et al., 2016), investigation of the possible major effects of spatio-temporal changes to water resources on socio-economic systems and ecosystems in arid areas, and predictions of scientific water cycle laws and water resource changing trends for arid areas.

3.3 Effects of climate change and human activities on water security in the northwest region

Climate change and human activities change water systems and affect water resource security. Studies on the effect of climate change on water resource security in the arid northwest region of China involve issues including river runoff processes, water availability and water demand under future climate change, as well as supply and demand imbalance caused by climate change (Liu et al., 2015). Thus, it is necessary to strengthen research on interactions and mechanisms of water inflow, availability and demand processes in the arid northwest region that integrates global changes, so as to construct a dynamic water system model with feedback mechanisms. There is also a need to carry out key vulnerability assessments of water systems in arid areas and research thresholds of water resource security management using hydrological landscape theory, vulnerability causal models and other methods to dynamically analyze key processes and vulnerabilities, and to understand the impact of climate change on various mechanisms of arid zones water systems and analyze the role of climate change and human activities in water resources. It is necessary to develop a dynamic model that comprehensively reflects the mutual feedback between water inflows, availability and demand; to analyze the impact of climate change and human activities on water inflow, availability and consumption processes; to identify key processes and key factors in maintaining water system stability and to analyze mechanisms of change; and to reveal key vulnerabilities of water systems and water security thresholds and their relation to climate change. In relation to the prominent conflict between ecology and economy in the development and utilization of water resources in the arid northwest region, and on the basis of an analysis of the hydrological, ecological and economic functions of water cycles within complex “water-ecology-social economy” systems, there is a need to carry out comprehensive research on response mechanisms to climate change of water cycles and water resources in arid areas and propose water management strategies for responding to climate change under coordinated ecological and economic development objectives. It is necessary, by developing and constructing water resource models suited to arid areas, to predict changes in future processes and intensity of water consumption for production and domestic use as well as eco-water consumption under climate change and socio-economic development scenarios, and to determine rational water resource allocation thresholds for “water-ecology-social economy” systems in arid areas. Finally, by analyzing the ability of water systems to adapt to climate change, and the degree to which they do so, as well as the impact of engineering techniques on the vulnerability of water systems, it will be possible to analyze water system stability and the relationship between socio-economic systems and ecological systems, explore the relationship between technological and economic input for adaptive control, and propose adaptive control countermeasures and models in response to climate change and for guaranteeing water resource security.

The authors have declared that no competing interests exist.

Arnell N, Tompkins E, Adger Net al., 2005. Vulnerability to abrupt climate change in Europe. Tyndall Centre Technical Report 34.Vulnerability to abrupt climate change in Europe

Boone A, Habets F, Noilhan Jet al., 2004. The Rhone-Aggregation land surface scheme intercomparison project: An overview.Journal of Climate, 17(1): 187-208.

Chen Y N, 2014. Water Resources Research in Northwest China. New York: Springer. doi: 10.1007/978-94-017-8017-9.This book examines the possible impacts of climate change on hydrology and water resources in the vast arid region of Northwest China, which is one of the world's largest arid places. The first chapter offers an introductory discussion of the physical geography and socioeconomic conditions in the region. Chapters 2 through 7 discuss the climate system and hydrologic system changes in the region...


Chen Y N, Deng H J, Li B Fet al., 2014a. Abrupt change of temperature and precipitation extremes in the arid region of Northwest China.Quaternary International, 336(12): 35-43.Not Available


Chen Y N, Li Z, Fan Y Tet al., 2014b. Research progress on the impact of climate change on water resources in the arid region of Northwest China.Acta Geographica Sinica, 69(9): 1295-1304. (in Chinese)The arid region of Northwest China is a special natural unit, which responds sensitively to the global climate change. Studies on the impact of climate change on water resources in the arid region of Northwest China have a significant effect on the adaptability of future climate change. Based on the latest research results, this paper analyzes the impacts of climate change on the formation and transformation of water resources and water cycle in the arid region of Northwest China. The results can be shown as follows: (1) The air temperature and precipitation in the arid region of Northwest China had a significant increasing trend in the past 50 years, however, the sharp increasing trend has retarded since the 21st century. (2) The temperature change in winter could be the most important factor for the unusually sharp rise in annual air temperature in this region. Moreover, the Siberian High and carbon dioxide emissions could be the most important reasons for the higher rate of the winter temperature rise. (3) Pan evaporation in the region exhibited an obvious decreasing trend until the early 1990s (1993), however, the downward trend reversed to go upward since 1993. The negative effects of warming and increasing evaporation on ecology have been highlighted in the arid region of Northwest China. (4) The glacier change has exerted great impact on water resources and its annual distribution in the arid region of Northwest China, and many rivers have passed the "Glacier inflexion". In the Tarim River Basin, the proportion of glacier melt water to runoff is high (e.g., as much as 50%) and it is supposed that the runoff may show a great fluctuation in the near future. Global warming not only increases the frequency and intensity of hydrological extremes, but also intensifies the fluctuation and uncertainty of inland rivers.


Chen Y N, Li Z, Fan Y Tet al., 2015. Progress and prospects of climate change impacts on hydrology in the arid region of Northwest China.Environmental Research, 139: 11-19.The arid region of Northwest China, located in the central Asia, responds sensitively to global climate change. Based on the newest research results, this paper analyzes the impacts of climate change on hydrology and the water cycle in the arid region of Northwest China. The analysis results show that: (1) In the northwest arid region, temperature and precipitation experienced “sharply” increasing in the past 50 years. The precipitation trend changed in 1987, and since then has been in a state of high volatility, during the 21st century, the increasing rate of precipitation was diminished. Temperature experienced a “sharply” increase in 1997; however, this sharp increasing trend has turned to an apparent hiatus since the 21st century. The dramatic rise in winter temperatures in the northwest arid region is an important reason for the rise in the average annual temperature, and substantial increases in extreme winter minimum temperature play an important role in the rising average winter temperature; (2) There was a significant turning point in the change of pan evaporation in the northwest arid area in 1993, i.e., in which a significant decline reversed to a significant upward trend. In the 21st century, the negative effects of global warming and increasing levels of evaporation on the ecology of the northwest arid region have been highlighted; (3) Glacier change has a significant impact on hydrology in the northwest arid area, and glacier inflection points have appeared in some rivers. The melting water supply of the Tarim River Basin possesses a large portion of water supplies (about 50%). In the future, the amount of surface water will probably remain at a high state of fluctuation.


Chen Y N, Li Z, Li W Het al., 2016. Water and ecological security: Dealing with hydroclimatic challenges at the heart of China’s Silk Road.Environmental Earth Sciences. doi: 10.1007/s12665-016-5385-z.

Crowley T J, 2000. Causes of climate change over the past 1000 years.Science, 289(5477): 270-277.Recent reconstructions of Northern Hemisphere temperatures and climate forcing over the past 1000 years allow the warming of the 20th century to be placed within a historical context and various mechanisms of climate change to be tested. Comparisons of observations with simulations from an energy balance climate model indicate that as much as 41 to 64% of pre-anthropogenic (pre-1850) decadal-sc...


Dai X G, Li W J, Ma Z Get al., 2006. The characteristics of Xinjiang water vapor source in recent years.Progress in Natural Science, 16(12): 1651-1656. (in Chinese)

Deng H J, Chen Y N, Wang H Jet al., 2015. Climate change with elevation and its potential impact on water resources in the Tianshan Mountains, Central Asia.Global and Planetary Change, 135: 28-37.Climate change in complex mountain regions has an impact on the change of water resources, especially in arid areas. Here, we use long-term meteorological and hydrological station observation data to analyze the time series of climate indices and runoff to study the variability of climate in the Kaidu River Basin. The analysis results are as follows: 1) the variability rate of low temperature indices are of greater magnitude than high temperature indices; 2) overall, for the river basin, frost days and ice days all exhibited decreasing trends, and growing season lengths increased considerably; 3) during the past 50 years, overall precipitation has increased in the river basin, but there are some differences in some seasons, and precipitation from June to August accounts for approximately 66% of the annual precipitation; and 4) temperature lapse rate and precipitation of the mountain region are major factors influencing the change of runoff for the Kaidu River Basin, temperature lapse rates are the main factor influencing the run off change in the spring and fall, and precipitation in the mountain region is the major factor influencing the runoff change in the summer. Generally, climate change in complex mountain regions will be expected to seriously affect water resources in arid regions.


Fan Y T, Chen Y N, Liu Y Bet al., 2013. Variation of baseflows in the headstreams of the Tarim River Basin during 1960-2007.Journal of Hydrology, 487: 98-108.The Tarim River is the largest inland river of China and a major water resource to the vast arid region in northwest China. For its four major headstreams, which contribute 98% of the Tarim River’s streamflow, we investigated the dynamics of baseflow in the past 50years. The digital filtering method was used to separate baseflow from surface flow, after which the baseflow index (BFI) was calculated and analyzed. The major findings of this study include (1) Baseflows of the four headstreams have increased considerably over the past 50years. The large baseflow index (BFI) usually occurred in the wet years but the change rate was irregular, because of the increasing recharge from snow and glacial meltwater. (2) The annual baseflow variation of the four headstreams appeared to have cycles of 3–5years, 10–14years, and 25years. (3) The baseflow and BFI showed obvious seasonal variation: The lowest baseflow and BFI typically occurred in December and January, and both increased gradually until the maximums reached in August or July. (4) The responses of runoff and baseflow to climatic factors were different. Precipitation possessed a great impact on runoff, whereas temperature possessed a great impact on baseflow. Baseflow is an important source to the Tarim River, and is affected by the increasing snow and glaciers melt as a result of temperature rise. For the four headstreams, we identified temperature thresholds in the time series of BFI and calculated regression relationships between temperature and BFI in the past 50years. The thresholds and the regression relationships would help to assess and predict the impact of climate change on headwater inflow to the Tarim River.


Fang G H, Yang J, Chen Y Net al., 2015. Comparing bias correction methods in downscaling meteorological variables for a hydrologic impact study in an arid area in China.Hydrology and Earth System Sciences, 19(6): 2547-2559.Water resources are essential to the ecosystem and social economy in the desert and oasis of the arid Tarim River basin, northwestern China, and expected to be vulnerable to climate change. It has been demonstrated that regional climate models (RCMs) provide more reliable results for a regional impact study of climate change (e.g., on water resources) than general circulation models (GCMs). However, due to their considerable bias it is still necessary to apply bias correction before they are used for water resources research. In this paper, after a sensitivity analysis on input meteorological variables based on the Sobol' method, we compared five precipitation correction methods and three temperature correction methods in downscaling RCM simulations applied over the Kaidu River basin, one of the headwaters of the Tarim River basin. Precipitation correction methods applied include linear scaling (LS), local intensity scaling (LOCI), power transformation (PT), distribution mapping (DM) and quantile mapping (QM), while temperature correction methods are LS, variance scaling (VARI) and DM. The corrected precipitation and temperature were compared to the observed meteorological data, prior to being used as meteorological inputs of a distributed hydrologic model to study their impacts on streamflow. The results show (1) streamflows are sensitive to precipitation, temperature and solar radiation but not to relative humidity and wind speed; (2) raw RCM simulations are heavily biased from observed meteorological data, and its use for streamflow simulations results in large biases from observed streamflow, and all bias correction methods effectively improved these simulations; (3) for precipitation, PT and QM methods performed equally best in correcting the frequency-based indices (e.g., standard deviation, percentile values) while the LOCI method performed best in terms of the time-series-based indices (e.g., Nash-Sutcliffe coefficient, R); (4) for temperature, all correction methods performed equally well in correcting raw temperature; and (5) for simulated streamflow, precipitation correction methods have more significant influence than temperature correction methods and the performances of streamflow simulations are consistent with those of corrected precipitation; i.e., the PT and QM methods performed equally best in correcting flow duration curve and peak flow while the LOCI method performed best in terms of the time-series-based indices. The case study is for an arid area in China based on a specific RCM and hydrologic model, but the methodology and some results can be applied to other areas and models.


Huang W, Feng S, Chen J Het al., 2015. Physical mechanisms of summer precipitation variations in the Tarim Basin in northwestern China. Journal of Climate, 28(9): 3579-3591.

IPCC, 2007. Climate change 2007: Synthesis report. Contribution of Working Groups I, II and III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge, UK and New York, USA: Cambridge University Press.

IPCC, 2013. Working Group I Contribution to the IPCC Fifth Assessment Report, Climate Change 2013: The Physical Science Basis: Summary for Policymakers.

Jiang Y, Luo Y, Zhao Z C, 2010. Projection of wind speed changes in China in the 21st century by climate models.Chinese Journal of Atmospheric Sciences, 34(2): 323-336. (in Chinese)19 IPCC (Intergovernmental Panel on Climate Change) AR4 (Fourth Assessment Report) climate models with the human emission of SRES (IPCC Special Report on Emissions Scenarios) A2, A1B and B1 have been employed to project the annual, seasonal and monthly wind speeds over the three sub-regions of China and the entire China for 2000-2099. The study also adds the projections of a new coupling climate model, BCC_CSM1.0.1, which was developed for IPCC AR5. Therefore, 20 climate models have been used in this research. As projected by 20 climate models with SRES A2, A1B, and B1, (1) the annual mean wind speeds in China for the 21st century decrease slightly, especially for SRES A2.(2) Among the four seasons, the wind speeds in winter decrease in the whole China and the three sub-regions. It is because the winter monsoon over East Asia weakens due to the global warming. The wind speed in summer over most of China increases as projected by a number of climate models. It is associated with the stronger summer monsoon over East Asia in the 21st century as projected by the climate models with SRES scenarios.(3) Compared with the model simulations for 1980-1999, the annual mean wind speeds during 2011-2030 decrease slightly for SRES A2 and do not change for SRES A1B and B1, respectively. The wind speeds during 2046-2065 and 2080-2099 for the three scenarios decrease more obviously than 1980-1999 and 2011-2030, respectively.(4) The wind speeds in winter (summer) for the three periods decrease (increase) relative to 1980-1999.(5) The geographical distributions of wind speed changes are different in winter and summer in comparison with 1980-1999. In summer, the increasing wind speeds are found over northeastern, northern, and central China. There are not obvious changes in other regions. In winter, the decreasing wind speeds over most of China are noticed, except for northern Northeast China and southeastern Tibet. More than 50% of the models project the patterns of wind changes conformably. It has a certain reliability.


Ju L X, Wang H J, 2006. Modern climate over East Asia simulated by a regional climate model nested in a global gridpoint general circulation model.Chinese Journal of Geophysics, 49(1): 52-60. (in Chinese)A ten-year simulation of present climate over East Asia was conducted with the model RegCM2 which is nested in a gridpoint general circulation model (IAP-AGCM) developed by IAP/CAS (Institute of Atmospheric Physics, Chinese Academy of Sciences) in one-way mode, and model results are tested and analyzed. The result shows that the RegCM2 has a reasonable ability to simulate spatial distributions and seasonal cycles of surface air temperature and precipitation, due to its high resolution and perfect physics course. Compared with the IAP-AGCM, the RegCM2 achieves much improvement. The spatial correlation coefficient (SCC) of annual surface air temperature increases from 0.92 to 0.94 and SCC of annual precipitation increases from 0.5 to 0.7 over China, respectively. One of the reasons is that the nested RegCM2 can capture mesoscale signals caused by sub-GCM grid scale forcings, which exist in observations but not in the IAP-AGCM.


Kaldybayev A, Chen Y N, Vilesov E, 2015. Glacier change in the Karatal river basin, Zhetysu (Dzhungar) Alatau, Kazakhstan.Annals of Glaciology, 57: 11-19.We investigated glacier changes in the Karatal river basin, the largest basin in Zhetysu (Dzhungar) Alatau, Kazakhstan, for the periods 19562001 and 2001-12, based on Landsat TM/ETM+ data analysis. In 1989, we found 243 glaciers with a total area of 142.8 km2; by 2012 these had shrunk to 214 glaciers with a total area of 109.3 km2, a decrease of 33.5 km2 over 23 years (1.02%a-1). This very high shrinkage rate is likely connected with a general trend of increasing temperatures, and small glaciers being situated at the relatively low altitude of the outer Zhetysu Alatau ranges. We also analyzed the shrinkage rate of glaciers based on their differences in size, altitude and aspect of slopes, as well as other topographic parameters, in four sub-basins where glacier shrinkage varied between 18% and 39%. Weather-station climate data showed a significant temperature increase and stable precipitation trends over the study period. We conclude that glacierized areas of the Karatal river basin are located in the most unfavorable conditions for glaciation, and as a result showed a higher shrinkage rate than other glacierized areas of the Tien Shan from 1956 to 2012.


Leary N, Conde C, Kulkarni Jet al., 2008. Climate change and vulnerability. Climate and Development, 1(1): 185-187.

Li B, Zhou T J, Wu C Qet al., 2009. Relationship between rainfall and sea surface temperature simulated by LASG/ IAP AGCM and CGCM.Chinese Journal of Atmospheric Sciences, 33(5): 1071-1086. (in Chinese)This paper evaluates the relationship between rainfall and sea surface temperature (thereafter SST) simulated by the new version of LASG/IAP (State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences) climate system model (FGOALS_s), which takes the recently improved version of spectral AGCM (SAMIL) as its atmospheric component. To understand the impacts of air-sea coupling on the simulation of relationship between rainfall and SST, results from FGOALS_s and AMIP-type simulations with SAMIL are compared. Since observational results show that rainfall anomalies are mainly forced by SST in the eastern equatorial Pacific and oceanic forcing from FGOALS_s is weaker than that from the observation, SAMIL has a better performance in simulating the relationship between rainfall and SST in the eastern equatorial Pacific. On the other hand, in summer and autumn, the SST anomalies in the western North Pacific are mainly induced by atmospheric forcing, so coupled model FGOALS_s can properly capture the nature of relationship between rainfall and SST because the air-sea coupling processes are included. Bias related to convection parameterization used in SAMIL leads to an increased surface downward shortwave radiation flux while rainfall increases in the eastern equatorial Pacific during September to November. To some extent, this discrepancy maintains after coupling. So it is urgent to improve the convection parameterization in the AGCM. Besides, it is found that the latent heat flux overly depends on the air-sea moisture differences in the coupled model.


Li B F, Chen Y N, Chen Z Set al., 2016a. Why does precipitation in Northwest China show a significant increasing trend from 1960 to 2010?Atmospheric Research, 167: 275-284.Based on monthly precipitation data from 74 weather stations in the arid region of northwest China, we employed statistical methods to analyse the characteristics of precipitation and investigated the relationships between precipitation and 11 atmospheric circulations. The results showed that the precipitation in northwest China had a significantly increasing trend (P < 0.01), at a rate of 0.61 mm/year, which is higher than the average rate of China (- 0.16 mm/year) for the same period. Annual precipitation increased markedly after 1987, but the increase in precipitation gradually declined from north to south and from west to east. We found that the precipitation variation in spring, summer, autumn, and winter plays an important role in the yearly change, accounting for 21.6%, 42.4%, 18.4%, and 17.6%, respectively. The correlation analysis indicated that the annual precipitation revealed strong and significant associations with the West Pacific Subtropical High (WPSH, R = 0.60, P < 0.001) and the North America Subtropical High (NASH, R = 0.57, P < 0.001) from 1960 to 2010. We therefore suggest that the strengthening of the WPSH and NASH after the mid-1980s is probably the main cause for the significant increasing trend of precipitation in northwest China.


Li B F, Chen Y N, Shi X2012. Why does the temperature rise faster in the arid region of Northwest China?Journal of Geophysical Research, 117: D16115.During 1960-2010, the air temperature in the arid region of northwest China had a significant rising trend (P < 0.001), at a rate of 0.343°C/decade, higher than the average of China (0.25°C/decade) and that of the entire globe (0.13°C/decade) for the same period. Based on the analysis of the data from 74 meteorological stations in the region for 1960-2010, we found that among the four seasons the temperature change of winter has been playing the most important role in the yearly change in this region. We also found that the winter temperature in this region has a strong association with the Siberian High (correlation coefficient: R = -0.715) and the greenhouse gas emission (R = 0.51), and between the two the former is stronger. We thus suggest that the weakening of the Siberian High during the 1980s to 1990s on top of the steady increasing of the greenhouse emission is the main reason for the higher rate of the temperature rise in the arid region of the northwest China.


Li B F, Chen Y N, Shi Xet al., 2013. Temperature and precipitation changes in different environments in the arid region of Northwest China.Theoretical and Applied Climatology, 112(3/4): 589-596.Using 51 meteorological stations in the arid region of northwest China in the mountain, oasis, and the desert areas obtained from 1960 to 2010, this paper conducted a comparative analysis for detecting temperature and precipitation changes in the diverse environments. In recent 50 years, temperature has increased at 0.325, 0.339, and 0.360 00°C per decade in the mountain, oasis, and the desert areas, respectively; and also, precipitation has increased at 10.15, 6.29, and 0.87 mm per decade, but in which the increasing trend of precipitation in desert area was not significant. Before the 1990s, the increase in temperature was the fastest in the desert area, up to 0.214 00°C per decade, but was the slowest in the mountain area, only 0.103 00°C per decade. The temperature rising was faster after the 1990s, 0.606 00°C per decade, in the oasis area was fastest, but was the slowest in the desert region with 0.402 00°C per decade. The precipitation in each area was stable from 1960 to 1986, but an increase in the oasis and mountain area was larger from 1987 to 2010.


Li B F, Chen Y N, Xiong H G, 2016b. Quantitatively evaluating the effects of climate factors on runoff change for Aksu River in northwestern China. Theoretical and Applied Climatology, 123(1/2): 97-105.Much attention has recently been focused on the effects that precipitation and potential evapotranspiration (PET) have had on runoff change; however, the influence of temperature on runoff needs to be


Li B F, Chen Z S, Yuan X Z, 2015. The nonlinear variation of drought and its relation to atmospheric circulation in Shandong Province, East China.Peer J, 3: e1289.Considerable attention has recently been devoted to the linear trend of drought at the decadal to inter-decadal time scale; however, the nonlinear variation of drought at multi-decadal scales and its relation to atmospheric circulation need to be further studied. The linear and nonlinear variations of the Palmer drought severity index (PDSI) in Shandong from 1900 to 2012 and its relations to the Pacific decadal oscillation (PDO), El Ni o-Southern Oscillation (ENSO), Siberian high (SH) and Southern Oscillation (SO) phase changes from multi-scale are detected using linear regression, the Mann endall test, ensemble empirical mode decomposition (EEMD) and the Pearson correlation analysis method. The results indicate that the PDSI shows no statistically significant linear change trend from 1900 to 2012; however, before (after) the late 1950s, PDSI shows a significant upward (downward) trend (P< 0.01) with a linear rate of 0.28/decade (0.48/decade). From 1900 to 2012, the PDSI also exhibits a nonlinear variation trend at the inter-annual scale (quasi-3 and quasi-7-year), inter-decadal scale (quasi-14-year) and multi-decadal scale (quasi-46 and quasi-65-year). The variance contribution rate of components from the inter-annual scale is the largest, reaching 38.7%, and that from the inter-decadal scale and multi-decadal scale are 18.9% and 19.0%, respectively, indicating that the inter-annual change exerts a huge influence on the overall PDSI change. The results also imply that the effect of the four atmospheric circulations (PDO, ENSO, SH, SO) on PDSI at the multi-decadal variability scale are more important than that at the other scales. Consequently, we state that PDSI variation at the inter-annual scale has more instability, while that at the inter-decadal and multi-decadal scale is more strongly influenced by natural factors.


Li Z, Chen Y N, Li W Het al., 2016. Potential impacts of climate change on vegetation dynamics in Central Asia.Journal of Geophysical Research, 120: 12345-12356.Observations indicate that although average temperatures in Central Asia showed almost no increases from 1997 to 2013, they have been in a state of high variability. Despite the lack of a clear increasing trend, this 15 year period is still the hottest in nearly half a century. Precipitation in Central Asia remained relatively stable from 1960 to 1986 and then showed a sharp increase in 1987. Since the beginning of the 21st century, however, the increasing rate of precipitation has diminished. Dramatic changes in meteorological conditions could potentially have a strong impact on the region's natural ecosystems, as some significant changes have already occurred. Specifically, the normalized difference vegetation index (NDVI) of natural vegetation in Central Asia during 1982-2013 exhibited an increasing trend at a rate of 0.004 per decade prior to 1998, after which the trends reversed, and the NDVI decreased at a rate of 0.003 per decade. Moreover, our results indicate that shrub cover and patch size exhibited a significant increase in 2000-2013 compared to the 1980s-1990s, including shrub encroachment on grasslands. Over the past 10 years, 8% of grassland has converted to shrubland. Precipitation increased in the 1990s, providing favorable conditions for vegetation growth, but precipitation slightly reduced at the end of the 2000s. Meanwhile, warming intensified 0.93°C since 1997 compared to the average value in 1960-1997, causing less moisture to be available for vegetation growth in Central Asia.


Li Z, Chen Y N, Shen Y Jet al., 2013. Analysis of changing pan evaporation in the arid region of Northwest China.Water Resources Research, 49: 2205-2212.1] Decreases in pan evaporation ( E p ) over the last decades have been reported in many regions of the world. In this study, we investigated E p dynamics in the hyper-arid region of China during the period 1958–2010 using a generic physical model based on long-term meteorological data collected at 81 ground-based meteorological stations. We also quantified the contribution of climatic factors to the E p change using partial derivatives. We found that E p in the region exhibited an obvious decreasing trend until early 1990s (1993), at a rate of 616.0 mm yr 612 . However, the downward trend reversed in 1993, and the rate of increase after that was 10.7 mm yr 612 . We also assessed the sensitivity of rates of evaporative demand to changes in aerodynamic and radiative components, and found that pan evaporation could be mostly attributed to changes in the aerodynamic component, with some regional contributions from solar irradiance. Observed near-surface wind speed is the primary contributor to the decline of pan evaporation during 1958–1993, while wind speed (WS) and vapor pressure deficit (VPD) were both major contributors to the increase of pan evaporation after 1993.


Li Z, Chen Y N, Yang Jet al., 2014. Potential evapotranspiration and its attribution over the past 50 years in the arid region of Northwest China.Hydrological Processes, 28(3): 1025-1031.<p>Evaporation paradox and its attribution have become a hot research topic in hydrology in recent years. This study estimates the potential evapotranspiration (ET<sub>0</sub>) using modified Penman&ndash;Monteith method and analyzes the corresponding trend attribution based on the long-term meteorological data collected at 81 ground-based meteorological stations in Northwestern arid region of China during the period 1958&ndash;2010. The analysis results show: (1) The ET<sub>0</sub> has exhibited an obvious decreasing trend until the early 1990s; however, the downward trend has been reversed to an upward trend after then. (2) Decrease in diurnal temperature range (DTR) and wind speed (WS) may lead to the decrease of ET<sub>0</sub> during 1956&ndash;1993. The change of dominant factors in the ET<sub>0</sub> trend has differences after the early 1990s; observed increase in WS is the primary factor contributing to the reversion of ET<sub>0</sub>. Copyright &copy; 2012 John Wiley &amp; Sons, Ltd.</p>


Lin Z Y, Zheng D, 1992. The tracks of moisture transportation and its vapour geoecological characteristics on the Qinghai-Xizang Plateau.Arid Zone Research, 9(2): 1-7. (in Chinese)In this paper, the tracks of moisture transportation in the Qinghai-Xizang Plateau (Tibet) and some characteristic analyses of rainfall in Ruoqiang are discussed. Some preliminary conclusions are obtained as follows:1. There are two tracks of moisture transportation: one is the east way, or from Bay of Bengal, along the Brahmaputra and Yarlugzangbo Rivers northward into the northern region of the plateau. It is possible that the water vapour of the Indean Ocean goes along this way and arrive at Ruoqiang region. The other is the west way but it varies with the seasons. In summer the tropical cloud systems leap over the Himalaya Mountains into the plateau; during the late fall and early winter the cloud mass comes from Pakistan and Afghanistan through the Pamir Plateau and gets into Ngari Region in Tibet.2. The rainfall in Ruoqiang becomes increasing in recent years. The annual precipitation in the 1950s was 16. 2 mm, 18. 0 mm in the 1960s, 20. 3 mm in the 1970s and 40. 2 mm in the 1980s.3. The annual average precipitation in Ruoqiang is 23. 8 mm. The abnormal rainfall in July of 1981 and 1988 were 73. 5 mm and 48. 2 mm, respectively. They led to serious flood damages in Ruoqiang.In addition, the relationship between the tracks of moisture transportation and distribution of vege -tation in the Qinghai-Xizang Plateau have been discussed.

Liu X R, Shen Y J, Guo Yet al., 2015. Modeling demand/supply of water resources in the arid region of northwestern China during the late 1980s to 2010. Journal of Geographical Sciences, 25(5): 573-591.Water demand increases continuously with an increasing population and economic development. As a result, the difference between water supply and demand becomes a significant issue, especially in arid regions. To figure out the utilization of water resources in the arid region of northwestern China (ARNWC), and also to provide methodologies to predict the water use in future, three models were established in this study to calculate agricultural irrigation, industrial and domestic water use in the ARNWC from the late 1980s to 2010. Based on river discharges in the region, the supply and demand of water resources at the river basin level were analyzed. The results indicated that agricultural irrigation demand occupies more than 90% of the total water use in the ARNWC. Total water demand increased from 31.97 km(3) in the late 1980s to 48.19 km(3) in 2010. Most river basins in this arid region were under medium and high water stress. Severe-risk river basins, such as the Shiyang river basin and the eastern part of the northern piedmont of the Tianshan Mountains, were found in this region. It was revealed that the water supply became critical from April to May, which was the season of the lowest water supply as determined by comparing monthly water consumption.


Ma L J, Zhao J F, Zang H Jet al., 2010. Impacts of glacier and snow melting on Bosten Lake under climate change.Arid Land Geography, 33(2): 210-216. (in Chinese)The impacts of melting of glacier and snow on the runoff of the Kaidu River and Bosten Lake's water level during the past 50 years were investigated by using the mass balance data of No.1 glacier,the runoff data from the Dashankou Hydrology Station,and observed data from the meteorological stations within the drainage area.Based on the statistical analysis of multivariate linear regression and the partial correlation,the research indicates that there is significant positive correlation between mass balance of No.1 glacier and annual runoff of the Kaidu River,but it can not explain all the changes of runoff.Analysis via partial correlation indicates that precipitation and snowmelt both have significant impact on runoff,and the coefficients are 0.57 and 0.40,respectively.The correlation coefficient between the fitting value of runoff from annual air temperature,precipitation,snowmelt and observed runoff reaches 0.63,which is far beyond 99.9% significant level.Analyses based on seasonal data reveal that precipitation and air temperature are,respectively,the main climatological factors influencing runoff in spring and autumn,and the partial correlation coefficients are 0.52 and 0.37,respectively.However,the impacts of glacier and snowmelt on runoff mainly occur in summer,which is the season of maximum runoff in the four seasons.The partial correlation coefficient between summer snowmelt and runoff is 0.51.As a result,the contribution of glacier and snowmelt to runoff in the drainage of Bosten Lake should be ignored by no means.


Mahlstein I, R Knutti, 2010. Regional climate change patterns identified by cluster analysis.Climate Dynamics, 35(4): 587-600.Climate change caused by anthropogenic greenhouse emissions leads to impacts on a global and a regional scale. A quantitative picture of the projected changes on a regional scale can help to decide on appropriate mitigation and adaptation measures. In the past, regional climate change results have often been presented on rectangular areas. But climate is not bound to a rectangular shape and each climate variable shows a distinct pattern of change. Therefore, the regions over which the simulated climate change results are aggregated should be based on the variable(s) of interest, on current mean climate as well as on the projected future changes. A cluster analysis algorithm is used here to define regions encompassing a similar mean climate and similar projected changes. The number and the size of the regions depend on the variable(s) of interest, the local climate pattern and on the uncertainty introduced by model disagreement. The new regions defined by the cluster analysis algorithm include information about regional climatic features which can be of a rather small scale. Comparing the regions used so far for large scale regional climate change studies and the new regions it can be shown that the spacial uncertainty of the projected changes of different climate variables is reduced significantly, i.e. both the mean climate and the expected changes are more consistent within one region and therefore more representative for local impacts.


Mimikou M, Blatas E, Varanaou Eet al., 2000. Regional impacts of climate change on water resources quantity and quality indicators.Journal of Hydrology, 234: 95-109.The impacts of climate change on water resources (surface runoff) and on water quality were assessed. Two GCM [global ciculation models]-based climate change scenarios were considered: transient (HadCM2) and equilibrium (UKHI). A conceptual, physically based hydrological model (WBUDG) was applied on a catchment in central Greece, simulating the effect of the two climate scenarios on average mon...


Montes-Hugo M, Doney S C, Ducklow Het al., 2009. Recent changes in phytoplankton communities associated with rapid regional climate change along the western Antarctic Peninsula.Science, 323(5920): 1470-1473.The climate of the western shelf of the Antarctic Peninsula (WAP) is undergoing a transition from a cold-dry polar-type climate to a warm-humid sub-Antarctic-type climate. Using three decades of satellite and field data, we document that ocean biological productivity, inferred from chlorophyll a concentration (Chl a), has significantly changed along the WAP shelf. Summertime surface Chl a (summer integrated Chl a ~63% of annually integrated Chl a) declined by 12% along the WAP over the past 30 years, with the largest decreases equatorward of 63 S and with substantial increases in Chl a occurring farther south. The latitudinal variation in Chl a trends reflects shifting patterns of ice cover, cloud formation, and windiness affecting water-column mixing. Regional changes in phytoplankton coincide with observed changes in krill (Euphausia superba) and penguin populations.


Nian Y Y, Li X, Zhou Jet al., 2014. Impact of land use change on water resource allocation in the middle reaches of the Heihe River Basin in northwestern China.Journal of Arid Land, 6(3): 273-286.In recent decades, China has been experiencing rapid economic development, population growth and urbanization. These processes have stressed the shortages of water resources in China, especially in the arid re-gions of northwestern China. In order to sustain the expanding cropland, people increased groundwater exploitation in these regions. The purpose of this study was to quantitatively analyze the changes in land use and water re-sources, and their relationship in the middle reaches of the Heihe River Basin, a typical inland river basin in northwest China. The data of land use change were interpreted using aerial photographs (1965) and Landsat TM images (1986 and 2007). The data of irrigation water volume in the irrigation districts were spatialized in the middle reaches of the Heihe River Basin. The spatial variation of the groundwater depth was interpolated using the geo-statistical method. The results showed that the cultivated cropland area along oasis fringe increased by 15.38% and 43.60% during the periods 1965&ndash;1986 and 1986&ndash;2007, respectively. Surface water amount for irrigation had almost doubled from 1956 to 2010. The decrease of grassland area mainly occurred at the alluvial fan in front of the Qilian Mountains, with 36.47% during 1965&ndash;1986 and 38.56% during 1986&ndash;2007, respectively. The groundwater depth in front of the mountain constantly increased from 1986 to 2007. We found that the overuse of surface water and overexploitation of groundwater had direct consequences on the natural environments. We suggests that the efficiency of surface water resources use among different irrigation districts needs to be improved, which will sig-nificantly ease the conflicts between increasing water demand for irrigation and a shortage of water resources in the middle reaches of the Heihe River Basin.


Patt A, Klein RJT, A dela Vega-Leinert, 2005. Taking the uncertainty in climate-change vulnerability assessment seriously.C R Geoscience, 337(4): 411-424.Climate-change vulnerability assessment has become a frequently employed tool, with the purpose of informing policy-makers attempting to adapt to global change conditions. However, we suggest that there are three reasons to suspect that vulnerability assessment often promises more certainty, and more useful results, than it can deliver. First, the complexity of the system it purports to describe is greater than that described by other types of assessment. Second, it is difficult, if not impossible, to obtain data to test proposed interactions between different vulnerability drivers. Third, the time scale of analysis is too long to be able to make robust projections about future adaptive capacity. We analyze the results from a stakeholder workshop in a European vulnerability assessment, and find evidence to support these arguments.


Patz J, 2001. Public health risk assessment linked to climatic and ecological change.Human and Ecological Risk Assessment: An International Journal, 7: 1317-1327.

Polsky C, Neff R, Yarna B, 2007. Building comparable global change vulnerability assessments: The vulnerability scoping diagram.Global Environmental Change, 17(3/4): 472-485.Advancing vulnerability science depends in part on identifying common themes from multiple, independent vulnerability assessments. Such insights are difficult to produce when the assessments use dissimilar, often qualitative, measures. The Vulnerability Scoping Diagram is presented to facilitate the comparison of assessments with dissimilar measures. The diagram is illustrated with recent research on drought vulnerabilities, showing that common insights into vulnerability may emerge if independent research teams use a common structure for organizing information about exposure, sensitivity and adaptive capacity—even if the underlying measures differ between assessments. Broadly adopting this technique, which is grounded in the “Eight Steps” methodological protocol [Schr02ter, D., Polsky, C., Patt, A., 2005. Assessing vulnerabilities to the effects of global change: an eight step approach. Mitigation and Adaptation Strategies for Global Change 10(4), 573–595], will enable a vulnerability meta-analysis, the lessons from which may permit places to identify helpful adaptation or mitigation options without first having to conduct their own vulnerability assessments.


Ren G Y, Xu M Z, Chu Z Yet al., 2005. Changes of surface air temperature in China during 1951-2004.Climatic and Environmental Research, 10(4): 717-727. (in Chinese)A data set from 726 stations was used to analyze surface air temperature change in Mainland China. The data set has been processed more carefully, and the main in-homogeneities existing in the monthly mean temperature data have been checked and corrected. The widely accepted procedures for creating area-averaged climatic time series and for calculating linear trend have been used. Analyses have been made for annual and monthly mean temperature. Annual mean surface air temperature in Mainland China as a whole rose by about 1.3 ℃ for the last 54 years, with a warming rate of about 0.25 ℃/10 a. The warming is more rapid than the average values of the world and the Northern Hemisphere. The most evident warming occurred in winter and spring as expected. Northeast China, North China and Northwest China experienced more significant warming in terms of annual mean temperature, while a cooling trend for southwestern China reported in earlier studies is still continuing. Summer mean temperature in the middle and lower reaches of the Yangtze River also decreased in the last 55 years. We have also tentatively analyzed the possible causes for the observed change in temperature.


Roy T, Bopp L, Gehlen Met al., 2011. Regional impacts of climate change and atmospheric CO2 on future ocean carbon uptake: A multimodel linear feedback analysis.Journal of Climate, 24(9): 2300-2318.The increase in atmospheric CO2 over this century depends on the evolution of the oceanic air sea CO2 uptake, which will be driven by the combined response to rising atmospheric CO2 itself and climate change. Here, the future oceanic CO2 uptake is simulated using an ensemble of coupled climate carbon cycle models. The models are driven by CO2 emissions from historical data and the Special Report on Emissions Scenarios (SRES) A2 high-emission scenario. A linear feedback analysis successfully separates the regional future (2010-2100) oceanic CO2 uptake into a CO2-induced component, due to rising atmospheric CO2 concentrations, and a climate-induced component, due to global warming. The models capture the observation-based magnitude and distribution of anthropogenic CO2 uptake. The distributions of the climate-induced component are broadly consistent between the models, with reduced CO2 uptake in the subpolar Southern Ocean and the equatorial regions, owing to decreased CO2 solubility; and reduced CO2 uptake in the midlatitudes, owing to decreased CO2 solubility and increased vertical stratification. The magnitude of the climate-induced component is sensitive to local warming in the southern extratropics, to large freshwater fluxes in the extratropical North Atlantic Ocean, and to small changes in the CO2 solubility in the equatorial regions. In key anthropogenic CO2 uptake regions, the climate-induced component offsets the CO2-induced component at a constant proportion up until the end of this century. This amounts to approximately 50% in the northern extratropics and 25% in the southern extratropics and equatorial regions. Consequently, the detection of climate change impacts on anthropogenic CO2 uptake may be difficult without monitoring additional tracers, such as oxygen.


Sanchez E, Dominguez M, Romera Ret al., 2011. Regional modeling of dry spells over the Iberian Peninsula for present climate and climate change conditions.Climatic Change, 107(3/4): 625-634.One of the major tasks of climate models is the description of precipitation characteristics. Many complex physical mechanisms are involved, and the corresponding parameterizations lead to more important differences among models for both present climate and climate change conditions than what is obtained for temperature analysis. Extreme precipitation events are more scarce, and therefore, differences are even larger. These processes are very relevant for impact studies, both when dealing with heavy precipitation events and also with drought conditions or dry spell description. But studies focused on dry spell analysis have received much less attention, compared with the ones related to large precipitation conditions. Present climate conditions already indicate important risks related to aridity over many areas of the world, and they are projected to be increased for future climate conditions. One good example of a region with these kind of risks is the Iberian Peninsula, where agricultural and socioeconomic impacts of water supply deficits are already a very relevant feature. The modeling results indicate that future climate will increase the mean and largest dry periods over most of the Iberian Peninsula, with a gradient of increase that is larger on the south and smaller on the north, therefore increasing the latitudinal contrast with respect to present climate. Regional features over certain basins and coasts are reproduced by the regional models, but not for the global climate model. Thus, future climate conditions point to a more severe hydrological stresses over several regions in the Iberian Peninsula.


Shi X L, Wang W, Shi W J, 2016. Progress on quantitative assessment of the impacts of climate change and human activities on cropland change.Journal of Geographical Sciences, 26(3): 339-354.It is important to study the contributions of climate change and human activities to cropland changes in the fields of both climate change and land use change. Relationships between cropland changes and driving forces were qualitatively studied in most of the previous researches. However, the quantitative assessments of the contributions of climate change and human activities to cropland changes are needed to be explored for a better understanding of the dynamics of land use changes. We systematically reviewed the methods of identifying the contributions of climate change and human activities to cropland changes at quantitative aspects, including model analysis, mathematical statistical method, framework analysis, index assessment and difference comparison. Progress of the previous researches on quantitative evaluation of the contributions was introduced. Then we discussed four defects in the assessment of the contributions of climate change and human activities. For example, the methods were lack of comprehensiveness, and the data need to be more accurate and abundant. In addition, the scale was single and the explanations were biased. Moreover, we concluded a clue about quantitative approach to assess the contributions from synthetically aspect to specific driving forces. Finally, the solutions of the future researches on data, scale and explanation were proposed.


Sun C J, Chen Y N, Li X G et al., 2016. Analysis on the streamflow components of the typical inland River, Northwest China.Hydrological Sciences Journal, 2016, 61(5): 970-981.AbstractRunoff generation and dynamics is an important issue in watershed and water resource management. Taking the Aksu river as a typical inland river, the spatial and temporal variations of δ18O and δD of the river water and its sources component pattern were investigated from May 2012 to May 2013. The results showed the following three main findings. Firstly, we analyzed the runoff generation and mechanism over a longer time-scale in two tributaries of the Aksu river. Secondly, 46–54% of the runoff in the Aksu River was derived from groundwater, 31–36% from glacier meltwater, 5–8.8% from snow meltwater, and 10% from precipitation. Third major finding was the significant inconsistency of the climate change impact on water resource. Specifically, our results showed that Toxkan river is recharged by more glacier meltwater (36%), and responds to sensitive temperature changes. Autumn runoff is more sensitive to changes of precipitation and temperature.


Sun F B, Roderick M L, Farquhar G Det al., 2010. Partitioning the variance between space and time.Geophysical Research Letters, 37: L12704.Here we decompose the space-time variance of near-surface air temperature using monthly observations for the global land surface (excluding Antarctica) from 1901-2000. To do that, we developed a new method for partitioning the total space-time variance, here called the grand variance, into separate spatial and temporal components. The temporal component is, in turn, further partitioned into the variance relating to different time periods and we use monthly data to decompose intra- and inter-annual components of the variance. The results show that the spatial and temporal components of the variance of near-surface air temperature have both, on average, decreased over time primarily because of reductions in the equator-to-pole (northern) temperature gradient, and because in cold regions, winter is generally warming faster than summer. We also found that in most regions, the inter-annual variance in near-surface air temperature has increased.


Sun G L, Chen Y N, Li W Het al., 2014. Intra-annual distribution and decadal change in extreme hydrological events in Xinjiang, northwestern China.Natural Hazards, 70(1): 119-133.We examined intra-annual characteristics and decadal change of extreme hydrological events occurring from 1901 to 2010 in Xinjiang, China, using concentration degree, concentration index, and Mann–Kendall tests. The results indicated that the concentration index in Xinjiang reached a maximum in summer for all areas, demonstrating that extreme hydrological events occurred mainly during summer (although Altay also showed a high winter concentration index). Intra-annual distribution was most concentrated in Turpan and Urumqi, followed by Kuytun–Shihezi and Aksu, with the concentration degree smallest in Altay. The frequency of extreme hydrological events exhibited an obvious increasing trend from 1901 to 2010, particularly post 1970s. Based on the results obtained in this study, the frequency, magnitude, and intensity of extreme hydrological events are expected to increase over time. In addition, the concentration degree and concentration index used to analyze intra-annual distribution of extreme hydrological events were proven to be reliable and will be useful for future studies. Copyright Springer Science+Business Media B.V. 2014


Tang G P, Li X B, Liu Y H, 2000. Assessment method of vulnerability of water resources under global climate change.Advance in Earth Sciences, 15(3): 313-317 (in Chinese)Global climate change has been extensively concerned by scientists, policy makers and the public, and become an important area of investigation in the social and natural sciences and engineering. Global climate change may have major impacts on aquatic ecosystems. The major impacts on water resources are the supply of water resources and the demand of water resources. The vulnerability assessment of water resources is comprehensive analysis of water resources ecosystem, including the supply and demand of water resources. Water resources in our country are deeply affected by climatic change, for example, the disequilibrium of distribution, the floods as well as the droughts. In addition, since the concerns with the global climate change were given, water resources vulnerability in respond to climatic change in our country has been or is being studied scarcely. Based on the reasons above, the assessment method of vulnerability of water resources under global climate change is probed in this paper, which aims at providing the scientific theoretic basis and foundation for the decision making of policy makers and the improvement of theory of vulnerability in our country.


Wang P Y, Li Z Q, Huai B Jet al., 2015. Spatial variability of glacier changes and their impact on water resources in the Chinese Tianshan Mountains during the last five decades.Journal of Arid Land, 7(6): 717-727.Changes in glaciers in the Chinese Tianshan Mountains have been analyzed previously. However, most pre-vious studies focused on individual glaciers and/or decentralized glacial basins. Moreover, a majority of these studies were published only in Chinese, which limited their usefulness at the international level. With this in mind, the authors reviewed the previous studies to create an overview of glacial changes in the Chinese Tianshan Mountains over the last five decades and discussed the effects of glacial changes on water resources. In response to climate change, glaciers in the Tianshan Mountains are shrinking rapidly and are ca. 20% smaller on average in the past five decades. Overall, the area reduction of glacial basins in the central part of the Chinese Tianshan Mountains is larger than that in the eastern and western parts. The spatial differentiation in glacial changes are caused by both differences in regional climate and in glacial factors. The effects of glacial changes on water resources vary in different river basins due to the differences in glacier distribution, char-acteristics of glacial change and proportion of the glacier meltwater in river runoff.


Wang S J, Zhang M J, Li Z Qet al., 2011. Glacier area variation and climate change in the Chinese Tianshan Mountains since 1960.Journal of Geographical Sciences, 21(2): 263-273.Based on the statistics of glacier area variation measured in the Chinese Tianshan Mountains since 1960, the response of glacier area variation to climate change is discussed systematically. As a result, the total area of the glaciers has been reduced by 11.5% in the past 50 years, which is a weighted percentage according to the glacier area variations of 10 drainage basins separated by the Glacier Inventory of China (GIC). The annual percentage of area changes (APAC) of glaciers in the Chinese Tianshan Mountains is 0.31% after the standardization of the study period. The APAC varies widely for different drainage basins, but the glaciers are in a state of rapid retreat, generally. According to the 14 meteorological stations in the Chinese Tianshan Mountains, both the temperature and precipitation display a marked increasing tendency from 1960 to 2009 at a rate of 0.34 degrees C.(10a)(-1) and 11 mm.(10a)(-1), respectively. The temperature in the dry seasons (from November to March) increases rapidly at a rate of 0.46 degrees C.(10a)(-1), but the precipitation grows slowly at 2.3 mm.(10a)(-1). While the temperature in the wet seasons (from April to October) grows at a rate of 0.25 degrees C.(10a)(-1), but the precipitation increases at 8.7 mm.(10a)(-1). The annual and seasonal climatic trends accelerate the retreat of glaciers.


Xu J H, Chen Y N, Li W Het al., 2014. Integrating wavelet analysis and BPANN to simulate the annual runoff with regional climate change: A case study of Yarkand River, Northwest China.Water Resources Management, 28(9): 2523-2537.

Xue J, Gui D W, Lei J Qet al., 2015. Reconstructing meteorological time series to quantify the uncertainties of runoff simulation in the ungauged Qira River Basin using data from multiple stations.Theoretical & Applied Climatology, 1-16. doi: 10.1007/s00704-015-1548-1.

Yang J, Castelli F, Chen Y Net al., 2014. Multiobjective sensitivity analysis and optimization of distributed hydrologic model MOBIDIC.Hydrology and Earth System Sciences, 18(10): 4101-4112.Calibration of distributed hydrologic models usually involves how to deal with the large number of distributed parameters and optimization problems with multiple but often conflicting objectives that arise in a natural fashion. This study presents a multiobjective sensitivity and optimization approach to handle these problems for the MOBIDIC (MOdello di Bilancio Idrologico DIstribuito e Continuo) distributed hydrologic model, which combines two sensitivity analysis techniques (the Morris method and the state-dependent parameter (SDP) method) with multiobjective optimization (MOO) approach -NSGAII (Non-dominated Sorting Genetic Algorithm-II). This approach was implemented to calibrate MOBIDIC with its application to the Davidson watershed, North Carolina, with three objective functions, i.e., the standardized root mean square error (SRMSE) of logarithmic transformed discharge, the water balance index, and the mean absolute error of the logarithmic transformed flow duration curve, and its results were compared with those of a single objective optimization (SOO) with the traditional Nelder-Mead simplex algorithm used in MOBIDIC by taking the objective function as the Euclidean norm of these three objectives. Results show that (1) the two sensitivity analysis techniques are effective and efficient for determining the sensitive processes and insensitive parameters: surface runoff and evaporation are very sensitive processes to all three objective functions, while groundwater recession and soil hydraulic conductivity are not sensitive and were excluded in the optimization. (2) Both MOO and SOO lead to acceptable simulations; e.g., for MOO, the average Nash-Sutcliffe value is 0.75 in the calibration period and 0.70 in the validation period. (3) Evaporation and surface runoff show similar importance for watershed water balance, while the contribution of baseflow can be ignored. (4) Compared to SOO, which was dependent on the initial starting location, MOO provides more insight into parameter sensitivity and the conflicting characteristics of these objective functions. Multiobjective sensitivity analysis and optimization provide an alternative way for future MOBIDIC modeling.


Yang T, Wang C, Yu Z Bet al., 2013. Characterization of spatio-temporal patterns for various GRACE-and GLDAS-born estimates for changes of global terrestrial water storage.Global and Planetary Change, 109: 30-37.Since the launch in March 2002, the Gravity Recovery and Climate Experiment (GRACE) satellite mission has provided us with a new method to estimate terrestrial water storage (TWS) variations by measuring earth gravity change with unprecedented accuracy. Thus far, a number of standardized GRACE-born TWS products are published by different international research teams. However, no characterization of spatio-temporal patterns for different GRACE hydrology products from the global perspective could be found. It is still a big challenge for the science community to identify the reliable global measurement of TWS anomalies due to our limited knowledge on the true value. Hence, it is urgently necessary to evaluate the uncertainty for various global estimates of the GRACE-born TWS changes by a number of international research organizations. Toward this end, this article presents an in-depth analysis for various GRACE-born and GLDAS-based estimates for changes of global terrestrial water storage. The work characterizes the inter-annual and intra-annual variability, probability density variations, and spatial patterns among different GRACE-born TWS estimates over six major continents, and compares them with results from GLDAS simulations. The underlying causes of inconsistency between GRACE- and GLDAS-born TWS estimates are thoroughly analyzed with an aim to improve our current knowledge in monitoring global TWS change. With a comprehensive consideration of the advantages and disadvantages among GRACE- and GLDAS-born TWS anomalies, a summary is thereafter recommended as a rapid reference for scientists, end-users, and policy-makers in the practices of global TWS change research. To our best knowledge, this work is the first attempt to characterize difference and uncertainty among various GRACE-born terrestrial water storage changes over the major continents estimated by a number of international research organizations. The results can provide beneficial reference to usage of different GRACE hydrology products to study TWS changes in different regions of the world. (c) 2013 Elsevier B.V. All rights reserved.


Yin Y, Clinton N, Luo Bet al., 2008. Resource system vulnerability to climate stresses in the Heihe river basin of western China.Climate Change and Vulnerability, 2: 88.

Zhang F Y, Ahmad S, Zhang H Qet al., 2016. Simulating low and high streamflow driven by snowmelt in an insufficiently gauged alpine basin.Stochastic Environmental Research and Risk Assessment, 30(1): 59-75.Snowmelt and water infiltration are two important processes of the hydrological cycle in alpine basins where snowmelt water is a main contributor of streamflow. In insufficiently gauged basins, hydrologic modeling is a useful approach to understand the runoff formation process and to simulate streamflow. In this study, an existing hydrologic model based on the principles of system dynamics was modified by using the effective cumulative temperature (>002°C) to calculate snowmelt rate, and the soil temperature to adjust the influence of the soil’s physical state on water infiltration. This modified model was used to simulate streamflows in the Kaidu River basin from 1982 to 2002, including normal, high, and low flows categorized by the Z index. Sensitivity analyses, visual inspection, and statistical measures were employed to evaluate the capability of the model to simulate various components of the streamflow. Results showed that the modified model was robust, and able to simulate the three categories of flows well. The model’s ability to reproduce streamflow in low-flow and normal-flow years was better than that in high-flow years. The model was also able to simulate the baseflow. Further, its ability to simulate spring-peak flow was much better than its ability to simulate the summer-peak flow. This study could provide useful information for water managers in determining water allocations as well as in managing water resources.


Zhang H F, Chen H S, 2011. Evaluation of summer circulation simulation over East Asia by 21 climate models. Part I: Climatology.Journal of the Meteorological Sciences, 31(2): 119-128. (in Chinese)Based on European Center for Medium range Weather Forecasting(ECMWF) 40 a reanalysis data(ERA40),the capabilities of 21 Coupled Ocean-Atmosphere General Circulation Models(CGCMs) from Intergovernmental Panel on Climate Change(IPCC) Fourth Assessment Report(AR4) to simulate the climatology of summer atmospheric general circulations in East Asia have been evaluated.Results show that:(1) Despite large differences among 21 models,the basic spatial patterns of the climatology of SLP,U,V wind and 500 hPa geopotential height are well simulated.On the whole,the simulation of 500 hPa potential height is the best,but the simulation of SLP is relatively poor;(2) The simulated SLP exhibits evident deficiency.Most of models can simulate 850 hPa U,V wind very well,on the average,the correlation coefficient of U with ERA40 is better than that of V.There are no obvious differences in the simulated 500 hPa geopotential height;(3) On the whole,the simulated climatology of the main circulation systems is weaker than ERA40,and the simulated western Pacific subtropical high is systematically weaker than the observation.


Zhang X Q, Sun Y, Mao W Fet al., 2010. Regional response of temperature change in the arid regions of China to global warming.Arid Land Geography, 27(4): 592-599.Under global warming,there was an obvious regional differentiation of climate change all over the world in the 20th century.During the past 30 years,a wide range of global warming took place,with the most remarkable warming in the middle and higher latitudes of the Northern Hemisphere.In the 21st century,the regional warming becomes more significant in the arid regions of China (ARC for short),and simultaneously the occurring frequency of extreme weather events increases.Under the influence of human activities and climate change,the natural environment has changed dramatically,e.g.,oasis degradation,land desertification,glacier retreat,water shortage,increasing natural disasters and obvious contradiction of the human-land relationship.Therefore,in the paper,the regional response of temperature change to global warming is investigated by using the daily temperature data at 77 typical meteorological stations in the ARC during the period from 1961 to 2007 and the methods of linear trend estimate,Mann-Kendall test and Morlet wavelet analysis.The results are as follows:(1) The response of temperature change in the ARC to global warming was characterized by the significant regional difference.The mean annual air temperature in the ARC was increased by 1.8 during the period of 1961-2007,its increase rate was 0.39 /10 a,which was obviously higher than the average of the globe and whole China;(2) The mean seasonal temperature in the ARC was increased more significantly in winter and autumn than that in spring and summer.There was an obvious regional difference of increases in mean annual and seasonal temperature,e.g.,the temperature was increased more significantly in north Xinjiang and the Alxa Plateau than that in south Xinjiang and the Hexi Corridor;(3) The abrupt change in temperature in the ARC occurred mainly after the mid-1980s.There were the 6-7-year annual temperature fluctuation periods and 16-17-year decadal ones.It can be inferred that the temperature in the ARC will be continuously increasing in the coming 10 years at least.Much more attention should be paid to studying how climate warming will affect the complex hydrological and thermal feedback mechanisms in the ARC.


Zhou X J, 2002. The suggestion of exploitation and utilization of air water resources in Northwest China. In: 2002 Scientific Development Report. Beijing: Science Press. (in Chinese)