An overview of the influence of atmospheric circulation on the climate in arid and semi-arid region of Central and East Asia

The arid and semi-arid (ASA) region of Asia occupies a large area in the middle latitudes of the Northern Hemisphere, of which the main body is the ASA region of Central and East Asia (CEA). In this region, the climate is fragile and the environment is sensitive. The eastern part of the ASA region of CEA is located in the marginal zone of the East Asian monsoon and is jointly influenced by westerly circulation and the monsoon system, while in the western part of the ASA of CEA, the climate is mainly controlled by westerly circulation. To understand and predict the climate over this region, it is necessary to investigate the influence of general circulation on the climate system over the ASA region of CEA. In this paper, recent progress in understanding the relationship between the general circulation and climate change over the ASA region is systematically reviewed. Previous studies have demonstrated that atmospheric circulation represents a significant factor in climate change over the ASA region of CEA. In the years with a strong East Asian summer monsoon, the water vapor flux increases and precipitation is abundant in the southeastern part of Northwest China. The opposite situation occurs in years when the East Asian summer monsoon is weak. With the weakening of the East Asian summer monsoon, the climate tends to dry over the semi-arid region located in the monsoon marginal zone. Recently, owing to the strengthening of the South Asian monsoon, more water vapor has been transported to the ASA region of Asia. The Plateau summer monsoon intensity and the precipitation in summer exhibit a significant positive correlation in Central Asia but a negative correlation in North China and Mongolia. A significant positive correlation also exists between the westerly index and the temperature over the arid region of CEA. The change in the westerly circulation may be the main factor affecting precipitation over the arid region of Central Asia.     

Accretionary processes and metallogenesis of the Central Asian Orogenic Belt: Advances and perspectives

As one of the largest Phanerozoic orogens in the world,the Central Asian Orogenic Belt (CAOB) is a natural laboratory for studies of continental dynamics and metallogenesis.This paper summarizes the research progresses of the accretionary processes and metallogenesis of the CAOB since the Peopled Republic of China was founded,and puts forward the prospect for future research.During the early period (1950s-1970s),several geological theories were applied to explain the geological evolution of Central Asia.In the early period of China's reform and opening-up,the plate tectonics theory was applied to explain the evolution of the northern Xinjiang and Xingmeng regions,and the opinion of subduction-collision between Siberian Kazakhstan and China-North Korea-Tarim plates was proposed.The idea of the Solonker-Yanbian suture zone was established.In the 1990s,the study of the CAOB entered a period of rapid development.One school of scholars including geologists from the former Soviet Union proposed a multi-block collision model for the assemblage of the CAOB.In contrast,another school of scholars,led by a Turkish geologist,Celal Sengor,proposed that the Altaids was formed through the growth and strike-slip duplicates of a single island arc,and pointed out that the Altaids is a special type of collisional orogen.During this period,Chinese geologists carried out a lot of pioneering researches on ophiolites and high-pressure metamorphic rocks in northern China,and confirmed the main suture zones accordingly.In 1999,the concept of"Central Asian metallogenic domain"was proposed,and it became one of the three major metallogenic domains in the world.Since the 21st century,given the importance for understanding continental accretion and metallogenic mechanism,the CAOB has become the international academic forefront.China has laid out a series of scientific research projects in Central Asia.A large number of important scientific research achievements have been spawned,including the tectonic attribution of micro-continents,timing and tectonic settings of ophiolites,magmatic arcs,identification and anatomy of accretionary wedges,regional metamorphism-deformation,(ultra)high-pressure metamorphism,ridge subduction plume-plate interaction archipelagic paleogeography and spatio-temporal framework of multiple accretionary orogeny,continental growth accretionary metallogenesis,structural superposition and transformation etc.These achievements have made important international influences.There still exist the following aspects that need further study:(1) Early evolution history and subduction initiation of the Paleo-Asian Ocean;(2) The accretionary mechanism of the extroversion Paleo-Asian Ocean;(3) The properties of the mantle of the Paleo-Asian Ocean and their spatiotemporal distribution;(4) The interaction between the Paleo-Asian Ocean and the Tethys Ocean;(5) Phanerozoic continental growth mechanism and its global comparison;(6) Accretionary metallogenic mechanism of the Central Asian metallogenic domain;and (7) Continental transformation mechanism.     

On the Problem of Distinction between Recent Geodynamics of Central and East Asia

Izvestiya, Physics of the Solid Earth - Abstract—The Central Asian and East Asian transitional zones are distinguished in Central and East Asia south of the Late Precambrian–Paleozoic...     

Wetlands of Northeast Asia and High Asia: an overview

This review reports background information on wetlands in the Northeast Asia and High Asia areas, including wetland coverage and type, significance for local populations, and threats to their vitality and protection, with particular focus on the relationship of how global change influenced wetlands. Natural wetlands in these areas have been greatly depleted and degraded, largely due to global climate change, drainage and conversion to agriculture and silviculture, hydrologic alterations, exotics invasions, and misguided management policies. Global warming has caused wetland and ice-sheet loss in High Asia and permafrost thawing in tundra wetlands in Northeast Asia, and hence induced enormous reductions in water-storage sources in High Asia and carbon loss in Northeast Asia. This, in the long term, will exacerbate chronic water shortage and positively feed back global warming. Recently, better understanding of the vital role of healthy wetland ecosystems to Asia’s sustainable economic development has led to major efforts in wetland conservation and restoration. Nonetheless, collaborative efforts to restore and protect the wetlands must involve not only the countries of Northeast and High Asia but also international agencies. Research has been productive but the results should be more effectively integrated with policy-making and wetland restoration practices under future climatic scenarios.     

Seismic hazard assessment in Central Asia: Outcomes from a site approach

In the process of updating existing PSHA maps in Central Asia, a first step is the evaluation of the seismic hazard in terms of macroseismic intensity by applying a data driven method. Following the Site Approach to Seismic Hazard Assessment (SASHA) [11], the evaluation of the probability of exceedance of any given intensity value over a fixed exposure time, is mainly based on the seismic histories available at different locations without requiring any a-priori assumption about seismic zonation. The effects of earthquakes not included in the seismic history can be accounted by propagating the epicentral information through a Intensity Prediction Equation developed for the analyzed area. In order to comply with existing building codes in the region that use macroseismic intensity instead of PGA, we evaluated the seismic hazard at 2911 localities using a macroseismic catalog composed by 5322 intensity data points relevant to 75 earthquakes in the magnitude range 4.6–8.3. The results show that for most of the investigated area the intensity having a probability of at least 10% to be exceeded in 50 years is VIII. The intensity rises to IX for some area struck by strong earthquakes in the past, like the Chou-Kemin-Chilik fault zone in northern Tien-Shan, between Kyrgyzstan and Kazakhstan, or in Gissar range between Tajikistan and Uzbekistan. These values are about one intensity unit less than those evaluated in the Global Seismic Hazard Assessment Program (GSHAP; Ulomov, The GSHAP Region 7 working group [29]). Moreover, hazard curves have been extracted for the main towns of Central Asia and the results compared with the estimates previously obtained. A good agreement has been found for Bishkek (Kyrgyzstan) and Dushanbe (Tajikistan), while a lower probability of occurrence of I=VIII has been obtained for Tashkent (Uzbekistan) and a larger one for I=IX in Almaty (Kazakhstan).     

A continuous simulation of Holocene effective moisture change represented by variability of virtual lake level in East and Central Asia

The fluctuation of a single lake level is a comprehensive reflection of water balance within the basin, while the regional consistent fluctuations of lake level can indicate the change of regional effective moisture. Previous researches were mainly focused on reconstructing effective moisture by multiproxy analyses of lake sediments. We carried out a series of experiments, including a transient climate evolution model, a lake energy balance model and a lake water balance model to simulate continuous Holocene effective moisture change represented by variability of virtual lake level in East and Central Asia.The virtual lake level, area, water depth and salinity are not equivalent to actual values, but we estimated relative changes of the regional effective moisture. We also explored the driving mechanisms of effective moisture change in different geographical regions. Our results indicated that gradually falling effective moisture during the Holocene in northern China was due to the combined effects of high lake evaporation caused by longwave and shortwave radiation, and low precipitation caused by reductions of summer solar insolation. A decline in effective moisture through the Holocene in the Tibetan Plateau and southern Central Asia resulted from decreased precipitation because of the weakening of the Asian summer monsoon. Increased precipitation induced by the strengthening of the westerly circulation contributed to the effective moisture rise during the Holocene in northern Central Asia.     

Response of plant growth to surface water balance during a summer dry period in the Kazakhstan steppe

In drylands, water deficit is the primary factor limiting plant growth. In the present study, surface energy balance and plant growth (above‐ground and below‐ground biomass) were measured continuously during the 2002 growing season in semiarid grassland in the northern part of Kazakhstan, Central Asia. Although there was above normal total rainfall during the 2002 growing season (May–November; 244 mm over 183 days), there was a dry period during July and August. Evaporative water was effectively supplied by precipitation and surface soil moisture during the wet season (May and June), during which time above‐ground biomass increased. During the early stages of the dry period, mature plants were likely to tap deeper sources of soil moisture, representing stored snowmelt water. As the soil moisture content decreased during the summer dry period due to the high levels of evapotranspiration and lack of precipitation, the evaporative fraction and above‐ground biomass rapidly decreased, whereas the below‐ground biomass increased. These results suggest that in summer, soil moisture acts to store water, and that soil moisture is essential for plant growth as a direct source of water during the dry period in natural grasslands in the Kazakhstan steppe. Copyright © 2007 John Wiley & Sons, Ltd.     

China's Transboundary Groundwater Cooperation in the Context of Emerging Transboundary Aquifer Law

China shares more than 20 transboundary aquifers with its coaquifer states, but they have not exploited their transboundary groundwater resources, and these resources have not been governed by any international agreements. Given the close interaction between surface water and groundwater, and the growing demands for transboundary groundwater in China and its coaquifer states, there is increasing necessity for these countries to undertake international cooperation on this issue. This article overviews China's transboundary aquifers, reviews the duty to cooperate on China's transboundary groundwater as well as the emerging transboundary aquifer law. It concludes by providing some proposals on international cooperation in this context, based on the two theories of international water law—limited territorial sovereignty and common interests, taking into account the practicability of China's cooperation with its coaquifer states. The author suggests that China cooperates with its coaquifer states through such means as the exchange of data and information, joint monitoring, the conclusion of bilateral or multilateral aquifer agreements, the establishment of joint management mechanisms, and international technical cooperation.     

Three Dimensional Crustal Density Structure of Central Asia and its Geological Implications

This paper introduces the scale-depth law of multi-scale wavelet analysis for regional gravity data processing, and presents the results of its application to Central Asia for computation of the 3D crustal density structures. The wavelet analysis method is applied for characterizing 3D crustal density structure, producing five maps of density disturbance corresponding to different depths of equivalent layers in the crust. The results provide important evidence for the study of crustal structures and mass movement in Central Asia: (i) the small-scale and intensive linear density disturbances in the upper crust indicate Phanerozoic orogenic belts; (ii) there exists a horseshoe-shaped low-density belt in the middle crust coinciding with the Kazakhstan orocline; (iii) there is a very low density zone in the lower crust, extending from western Kunlun to Tianshan, probably indicating a lower-crust flow; (iv) there are a few lowdensity spots in the middle crust, which might be caused by low-density mass squeezing upward from the lower crust flows.     

River management system development in Asia based on Data Integration and Analysis System (DIAS) under GEOSS

This paper introduces the process of development and practical use implementation of an advanced river management system for supporting integrated water resources management practices in Asian river basins under the framework of GEOSS Asia water cycle initiative (AWCI). The system is based on integration of data from earth observation satellites and in-situ networks with other types of data, including numerical weather prediction model outputs, climate model outputs, geographical information, and socio-economic data. The system builds on the water and energy budget distributed hydrological model (WEB-DHM) that was adapted for specific conditions of studied basins, in particular snow and glacier phenomena and equipped with other functions such as dam operation optimization scheme and a set of tools for climate change impact assessment to be able to generate relevant information for policy and decision makers. In situ data were archived for 18 selected basins at the data integration and analysis system of Japan (DIAS) and demonstration projects were carried out showing potential of the new system. It included climate change impact assessment on hydrological regimes, which is presently a critical step for sound management decisions. Results of such three case studies in Pakistan, Philippines, and Vietnam are provided here.     

Features and trends of the environmental change in the arid areas in Central Asia

RS-monitoring index systems of ecological environment changes at a large scale, based on empirical data and trends in environmental change in Central Asia, are developed using NOAA and MODIS data. Moreover, with the help of mathematical statistics and GIS spatial analysis, the degrees, hazards and distribution extent of various possible ecological problems are discussed, environmental changes in Central Asia in 1990 and 2005 are separately evaluated, and dynamic changes in the environment in Central Asia over a 15-year period are analyzed. The results reveal that during the 15-year period from 1990 to 2005, areas of degenerated vegetation in Kazakhstan, Uzbekistan, Turkmenistan, Kirghizstan and Tadzhikistan were enlarged by 0.069×10⁵ km², 0.081×10⁵ km², 0.296×10⁵ km², 0.022×10⁵ km² and 0.112×10⁵ km², respectively. The ecological environment in Central Asia was in the state of significant degeneration and even deterioration. This study proves that NOAA and MODIS data can be used to successfully monitor the environment and provide useful results.     

Exploring the history of cultural exchange in prehistoric Eurasia from the perspectives of crop diffusion and consumption

The history of cultural exchange in prehistoric Eurasia(CEPE) has been widely investigated. Based on archaeological evidence, this process is thought to date back to at least the early Bronze Age, although details about timings and routes remain unclear. It is likely that CEPE promoted the spread and exchange of crops that originated in different parts of Eurasia; since these remains can be definitely identified and directly dated, they provide ideal research materials to explore the history of CEPE. In this paper, we review the available archaeobotanical evidence and direct radiocarbon dates for crop remains, alongside carbon isotopic data from human bones unearthed from prehistoric sites in Eurasia, in order to investigate the history of the spread of millet crops, and wheat and barley, that were first domesticated in the eastern and western parts of Eurasia during prehistoric times.In combination with other archaeological evidences, we discuss the history of CEPE. Our results suggest that wheat and barley were domesticated in western Asia around 10500 a BP, spread into Europe and western Central Asia before 8000 a BP, and reaching eastern Central Asia and northwestern China between 4500 and 4000 a BP. Data show that both broomcorn and foxtail millet were domesticated in eastern Asia before 7700 a BP, spread into eastern Central Asia between 4500 and 4000 a BP, and into western Asia and Europe prior to 3500 a BP. Wheat, barley, and millet crops were first utilized together in eastern Kazakhstan within Central Asia around 4400 a BP, the region where earliest CEPE is likely to have taken place. These crops were mixedly used mainly in eastern central Asia and northwest China between 4500 and 3500 a BP, and then across the Eurasia before 2200 a BP. The results of this study suggest that transcontinental CEPE might have been initiated during the fifth millennium, before intensifying during the Bronze Age to lay the foundations for the creation of the ancient Silk Road during the Han Dynasty(between 202 BC and 220AD).     

Reflections on the 50-year international search for integrated water management

In the roughly 70 yr since the concept of integrated water management in river basins replaced primarily single-purpose management, there has been increasing question by international science and policy agencies as to the full consequences of such strategies for both social and environmental systems and for fulfillment of the notions underlying sustainable development. The experience suggests there is continuing urgent need for expanding the range of management measures considered as part of the planning process; for deepening the quality of criteria to judge each measure for reconciling the various evaluation principles; and for making incisive, correct post-audits of what actually resulted from their applications. It also reminds us that realization of the full potential of truly integrated water management may be very long in coming. Problems of improved analysis and of necessary institutional reform are formidable.     

Advances in carbon flux observation and research in Asia

As an important component of FLUXNET, Asia is increasingly becoming the hotspot in global carbon research for its vast territory, complex climate type and vegetation diversity. The present three regional flux observation networks in Asia (i.e. AsiaFlux, KoFlux and ChinaFLUX)have 54 flux observation sites altogether, covering tropic rainforest, evergreen broad-leaved forest, broad-leaved and coniferous mixed forest, shrubland, grassland, alpine meadow and cropland ecosystems with a latitudinal distribution from 2°N to 63°N. Long-term and continuous fluxes of carbon dioxide, water vapor and energy between the biosphere and atmosphere are mainly measured with eddy covariance technique to (1) quantify and compare the carbon, water and energy budgets across diverse ecosystems; (2) quantify the environmental and biotic controlling mechanism on ecosystem carbon, water and energy fluxes; (3) validate the soil-vegetation-atmosphere model; and (4) serve the integrated study of terrestrial ecosystem carbon and water cycle. Over the last decades, great advancements have been made in the theory and technology of flux measurement, ecosystem flux patterns, simulation and scale conversion by Asian flux community. The establishment of ChinaFLUX has greatly filled the gap of flux observation and research in Eurasia. To further promote the flux measurement and research,accelerate data sharing and improve the data quality, it is necessary to present a methodological system of flux estimation and evaluation over complex terrain and to develop the integrated research that combines the flux measurement, stable isotope measurement, remote sensing observation and GIS technique. It also requires the establishment of the Joint Committee of Asian Flux Network in the Asia-Pacific region in order to promote the cooperation and communication of ideas and data by supporting project scientists, workshops and visiting scientists.     

Lessons learned from the change from supply to demand water management in irrigated agriculture: a case study from Pakistan

Scarcity of good quality water has led many countries to introduce demand-based water management in the irrigated agriculture section in place of the existing supply-based water management. This transition requires institutional changes, including the formation of Water User Associations (WUAs). The paper reviews the constraints of irrigated agriculture in Pakistan and discusses the conditions for success in the formation of farmers’ organizations. This paper seeks to show that the development of WUAs is a vital step in the development of integrated water resource management. It is argued that IWRM is a prerequisite for a sustainable society in water-dependent countries that are increasingly water-scarce—like the paternalistic and bureaucratic societies of South Asia.     

Hydrologic impact of regional climate change for the snow‐fed and glacier‐fed river basins in the Republic of Tajikistan: statistical downscaling of global climate model projections

Climate change due to global warming is a public concern in Central Asia. Because of specific orography and climate conditions, the republic of Tajikistan is considered as the main glacial center of Central Asia. In this study, regional climate change impacts in the two large basins of Tajikistan, Pyanj and Vaksh River basins located in the upstream sector of the Amu Darya River basin are analysed. A statistical regression method with model output statistics corrections using the ground observation data, Willmott archived dataset and GSMaP satellite driven dataset, was developed and applied to the basins to downscale the Global Climate Model Projections at a 0.1‐degree grid and to assess the regional climate change impacts at subbasin scale. It was found that snow and glacier melting are of fundamental importance for the state of the future water resources and flooding at the target basins since the air temperature had a clearly increasing trend toward the future. It was also found that the snowfall will decrease, but the rainfall will increase because of the gradual increase in the air temperature. Such changes may result in an increase in flash floods during the winter and the early spring, and in significant changes in the hydrological regime during a year in the future. Furthermore, the risks of floods in the target basins may be slightly increasing because of the increase in the frequencies and magnitudes of high daily precipitation and the increase in the rapid snowmelt with high air temperatures toward the future. Copyright © 2012 John Wiley & Sons, Ltd.     

Is Mongolia's groundwater increasing or decreasing? The case of the Kherlen River basin / Les eaux souterraines de Mongolie s'accroissent ou décroissent-elles? Cas du bassin versant la Rivière Kherlen

Abstract

The average area-wide underground terrestrial water storage in the Kherlen River basin, a relatively pristine area in eastern Mongolia where human impacts have been minimal so far, has undergone a marked decline in the past decade; nevertheless, there is no evidence that any unusual or systematic long-term storage change has taken place over the past half century. This result follows from an analysis of daily streamflow records measured at three gauging stations on the river, namely at Baganuur, Undurkhaan and Choibalsaan. This absence of a clear trend in long-term groundwater storage is generally consistent with findings in previous studies regarding trends of other components of the hydrological cycle in Mongolia and neighbouring regions at similar latitudes, namely in northern Inner Mongolia to the east and Xinjiang to the west, and even further in the same direction in the adjacent areas of southern Central Asia of the Russian Federation and of Kazakhstan.     

1975-2007年中亚干旱区内陆湖泊面积变化遥感分析

中亚干旱区内陆湖泊的湖面变化反映了气候波动和人类活动对流域水文过程的影响.本文以中亚干旱区平原区尾闾湖泊、吞吐湖泊和高山湖泊三类典型内陆湖泊为研究对象,利用1975-2007年Landsat遥感影像,基于归一化水体指数提取湖泊水域边界信息,分析近30年来内陆湖泊湖面变化特征.结果表明,近30年来,研究区内有超过一半的内...     

中亚造山带东段软流圈分布特征——基于长周期大地电磁探测的结果

中亚造山带东段经历了古亚洲洋、蒙古—鄂霍茨克洋和古太平洋构造体制的多重作用,多期次的构造活动不仅改造了地形地貌、岩石圈结构,同时也改造了软流圈分布,因此对软流圈结构研究具有重要的科学意义.为了揭示复杂多重构造体系下软流圈的分布特征,完成了中亚造山带东段约1800km长大地电磁测深剖面,并对数据进行非线性共轭梯度反演,获得二维电性结构模型.研究发现:中亚造山带东段岩石圈内部存在多处低阻异常,地表多对应第四纪火山群或古缝合带,表明这些低阻异常与软流圈上侵有关.软流圈呈现高导特征,南部略薄,电阻率值为10～30Ωm,北部厚度较大,电阻率值为10～0.1Ωm,这种电性结构特征体现了中亚造山带东段软流圈南北两侧厚度、部分熔融程度的不均一性.而已有的层析成像结果显示中亚造山带软流圈东西向则呈现东厚西薄的特征.结合区域地质,提出软流圈与岩石圈一样在碰撞造山过程中厚度、部分熔融程度也会随之变化的动力学认识.中亚造山带东段软流圈主要经历了古亚洲洋构造体系、蒙古—鄂霍茨克构造体系和太平洋构造体系三阶段的构造事件影响,因此中亚造山带东段软流圈的南北向差异,推断为古亚洲洋闭合早于鄂霍茨克洋闭合的时限差异所致,东西向差异则主要受太平洋构造体系的影响.