Climate change,migration, and regional administrative reform: A case study of Xinjiang in the middle Qing Dynasty(1760–1884)

Based on historical records of extreme climate events and population densities in Gansu and Shaanxi, and information on climate change, populations, new cultivated cropland, and administrative system reform in Xinjiang, this study explores the interaction between climate change, migration, and regional administrative reform in the middle Qing Dynasty. The results showed that the surge in population migration from Gansu and Shaanxi to Xinjiang during 1760–1820 was caused by extreme climate events(droughts and floods) and population pressure in Gansu and Shaanxi. During 1760–1880, the climate in Xinjiang was unusually cold and humid, which was highly conducive to abundant regional water resources. This provided favorable conditions for farmland irrigation and further promoted agricultural cultivation, population growth, and town development within this region. Additionally,the interactions between climate change and the above-mentioned social factors, which acted as driving forces, spurred the reform in the administrative system of Xinjiang whereby the military administration system was transformed to a province administration system. Through this reform, the Qing government managed to restore peace and stability in Xinjiang. This study contributes to a better understanding of climate-related population migration and enhances our knowledge of the impact-response chain between climate change, ancient social developments, and political coping strategies, especially in regional administrative reform.     

Multi-city sustainable regional urban growth simulation—MSRUGS: a case study along the mid-section of Silk Road of China

Urban growth along the middle section of the ancient silk-road of China (so called West Yellow River Corridor—He-Xi Corridor) has taken a unique path deviating from what is commonly seen in the coastal China. Urban growth here has been driven by historical heritage, transportation connection between East and West China, and mineral exploitation. However, it has been constrained by water shortage and harsh natural environment because this region is located in arid and semi-arid climate zones. This paper attempts to construct a multi-city agent-based model to explore possible trajectories of regional urban growth along the entire He-Xi Corridor under a severe environment risk, over urban growth under an extreme threat of water shortage. In contrast with current ABM approaches, our model will simulate urban growth in a large administrative region consisting of a system of cities. It simultaneously considers the spatial variations of these cities in terms of population size, development history, water resource endowment and sustainable development potential. It also explores potential impacts of exogenous inter-city interactions on future urban growth on the basis of urban gravity model. The algorithmic foundations of three types of agents, developers, conservationists and regional-planners, are discussed. Simulations with regard to three different development scenarios are presented and analyzed.     

Land use effects on climate in China as simulated by a regional climate model

A regional climate model (RegCM3) nested within ERA40 re-analyzed data is used to investigate the climate effects of land use change over China. Two 15-year simulations (1987―2001), one with current land use and the other with potential vegetation cover without human intervention, are conducted for a domain encompassing China. The climate impacts of land use change are assessed from the difference between the two simulations. Results show that the current land use (modified by anthropogenic ac- tivities) influences local climate as simulated by the model through the reinforcement of the monsoon circulation in both the winter and summer seasons and through changes of the surface energy budget. In winter, land use change leads to reduced precipitation and decreased surface air temperature south of the Yangtze River, and increased precipitation north of the Yangtze River. Land use change signifi- cantly affects summer climate in southern China, yielding increased precipitation over the region, de- creased temperature along the Yangtze River and increased temperature in the South China area (south-end of China). In summer, a reduction of precipitation over northern China and a temperature rise over Northwest China are also simulated. Both daily maximum and minimum temperatures are affected in the simulations. In general, the current land use in China leads to enhanced mean annual precipitation and decreased annual temperature over south China along with decreased precipitation over North China.     

Urban expansion in China and its effect on cultivated land before and after initiating “Reform and Open Policy”

Urbanization in China has expanded at an unprecedented speed since the declaration of "Reform and Open Policy"and presented many challenges. Unbalanced regional development, appearance of super megacities and concomitant problems,and conflicts between urbanization and cultivated land protection are three critical problems that Chinese urbanization has to face. To develop new plans for foreseeable future urbanization in China, it is critical to understand the evolving history of cities across China. This study maps urban expansion of 60 typical Chinese cities based on large amount of remote sensing data and the labor-intensive image interpretation method, in order to understand the history of urban expansion from the 1970 s to 2013.Results showed that area of cities expanded 5.23 times compared to their area in the 1970 s. Urban expansion in China accelerated three times(1988–1996, 1999–2006, and 2009–2011) and decelerated three times(1997–1998, 2007–2008, and 2012–2013) over the 40 years. The urban area of South China expanded most significantly 9.42 times, while the urban area in Northeast China expanded only 2.37 times. The disparity among different administrative ranks of cities was even greater than(3.81 times) the differences among different regions. Super megacities have been continuously expanding at a fast rate(8.60-fold), and have not shown obvious signs of slowing down. The proportion of cultivated land among the land sources for urban expansion decreased to a small extent in the 1990 s, but cultivated land continues to be the major land source for urban expansion. Effective future urbanization needs controlling the expansion scale of large cities and reasonably developing medium and small cities, as well as balancing regional development.     

酒西盆地断层活动特征及古地震研究

通过室内航片判读和野外调查 ,在酒西盆地发现 3条全新世活动逆掩断层 ,它们全新世以来的垂直活动速率都很接近 ,为 0 18～ 0 2 5mm/a。通过探槽揭露出的 3条断层全新世以来各发生两次古地震事件。根据探槽揭露的古地震年代及断层活动所形成的微地貌特征分析 ,阴洼山断层是独立活动的 ;北大河断层和新民堡断层上的古地震事件在时间上可能非常接近 ,具有丛集特征 ,或者是一次地震事件分别破裂这两条断层 ,但目前的测年手段还无法区别它们是一次破裂事件形成还是时间上非常接近的两次事件所形成的     

河西走廊东段湖泊旋回及其古气候意义

以河西走廊东段石羊河尾闾青土湖为例,通过对志云村剖面沉各气候记录的研究,证实季风边缘是年以上时间尺度的气候变化,具有暖湿,冷干的阶段性特征。自６０００ａＢＰ以来,河西走廊东段渗湖泊回经历了四次湖退和三次湖进过程。除最后一次湖退直至干涸受人类活动影响较大外,其它主要是气候阶段性变化的结果。     

Impact of land-use change on hydrological processes in the Maying River basin, China

Since the 1960s, dramatic changes have taken place in land-use patterns characterized by the persistent expansion of cultivated land and a continuous decrease in natural woodland and grassland in the arid inland river basins of China. It is very important to assess the effects of such land-use changes on the hydrological processes so vital for water resource management and sustainable development on the catchment scale. The Maying River catchment, a typical arid inland watershed located in the middle of the Hexi Corridor in northwest China, was the site chosen to investigate the hydrological responses to land-use changes. The annual runoff, base flow, maximum peak flow, and typical seasonal runoff in both spring and autumn flood periods were selected as the variables in the hydrological processes. Statistical-trend analysis and curvilinear regression were utilized to detect the trends in hydrological variables while eliminating the climatic influence. The relationship between cultivated land-use and hydrological variables was analyzed based on four periods of land-use variation data collected since 1965. A runoff model was established composed of two factors, i.e., cultivated land use and precipitation. The impact of land use changes, especially in the large ar- eas of upstream woodland and grassland turned into cultivated lands since 1967, has resulted in a mean annual runoff decrease of 28.12%, a base flow decline of 35.32%, a drop in the maximum peak discharge of 35.77%, and mean discharge decreases in spring and autumn of 36.05% and 24.87% respectively, of which the contribution of cultivated land expansion to the influence of annual runoff amounts to 77%-80%, with the contribution to the influence of spring discharge being 73%-81%, and that to the influence of base flow reaching 62%-65%. Thus, a rational regulation policy of land use patterns is vitally important to the sustainable use of water resources and the proper development of the entire catchment.     

Quantitative analysis of agricultural land use change in China

This article reviews the potential impacts of climate change on land use change in China. Crop sown area is used as index to quantitatively analyze the temporal–spatial changes and the utilization of the agricultural land. A new concept is defined as potential multiple cropping index to reflect the potential sowing ability. The impacting mechanism, land use status and its surplus capacity are investigated as well. The main conclusions are as following;

• 1.During 1949–2010, the agricultural land was the greatest in amount in the middle of China, followed by that in the country’s eastern and western regions. The most rapid increase and decrease of agricultural land were observed in Xinjiang and North China respectively, Northwest China and South China is also changed rapid. The variation trend before 1980 differed significantly from that after 1980.
• 2.Agricultural land was affected by both natural and social factors, such as regional climate and environmental changes, population growth, economic development, and implementation of policies. In this paper, the effects of temperature and urbanization on the coverage of agriculture land are evaluated, and the results show that the urbanization can greatly affects the amount of agriculture land in South China, Northeast China, Xinjiang and Southwest China.
• 3.From 1980 to 2009, the extent of agricultural land use had increased as the surplus capacity had decreased. Still, large remaining potential space is available, but the future utilization of agricultural land should be carried out with scientific planning and management for the sustainable development.

     

Modelling hydrological response to different land‐use and climate change scenarios in the Zamu River basin of northwest China

Changes in climate and land use can significantly influence the hydrological cycle and hence affect water resources. Understanding the impacts of climate and land‐use changes on streamflow can facilitate development of sustainable water resources strategies. This study investigates the flow variation of the Zamu River, an inland river in the arid area of northwest China, using the Soil and Water Assessment Tool distributed hydrological model. Three different land‐use and climate‐change scenarios were considered on the basis of measured climate data and land‐use cover, and then these data were input into the hydrological model. Based on the sensitivity analysis, model calibration and verification, the hydrological response to different land‐use and climate‐change scenarios was simulated. The results indicate that the runoff varied with different land‐use type, and the runoff of the mountain reaches of the catchment increased when grassland area increased and forestland decreased. The simulated runoff increased with increased precipitation, but the mean temperature increase decreased the runoff under the same precipitation condition. Application of grey correlation analysis showed that precipitation and temperature play a critical role in the runoff of the Zamu River basin. Sensitivity analysis of runoff to precipitation and temperature by considering the 1990s land use and climate conditions was also undertaken. Copyright © 2007 John Wiley & Sons, Ltd.     

南北地震带北段的地壳速度结构及其构造启示

收集和拾取了“中国地震科学台阵”探测项目在南北地震带北段布设的680个流动地震台站和中国地震台网217个固定台站所记录的地震事件的P波和S波初至到时,通过层析成像研究获得了南北地震带北段水平网格间距为0.33°×0.33°的地壳P波和S波速度分布。结果显示:在30 km深度上青藏高原东北部表现为显著的整体性低速异常,低速异常区向南延伸至龙门山断裂,以106°E为界线将秦岭造山带分为西侧的低速异常和东侧的高速异常,并沿银川—河套地堑向东北展布,向北穿过河西走廊,在阿拉善地块表现为低速异常,这可能暗示了青藏高原向东的扩展被较为坚固的四川盆地和秦岭造山带阻挡,而向北的扩展可能影响到了河西走廊至阿拉善地块,并沿银川—河套地堑影响到鄂尔多斯西北缘;在50 km深度上,阿拉善地块、祁连造山带东段显示高速异常,有可能是阿拉善地块向祁连东段下方俯冲所致。研究区内大部分地震分布在P波和S波高低速异常相间及速度剧烈变化的地区,M≥6.0强震几乎全部投影在30 km深度的低速异常区域内,说明强震发生的背景可能与地震源区下方的低速区有关。      

Spatiotemporal Characteristics of Evapotranspiration and Driving Factors in the Bosten Lake Watershed,China

The Bosten Lake watershed investigated in this study has seen significant land cover and climate change. The spatiotemporal relationship between evapotranspiration (ET) and environmental factors remain unclear. In this study, trend analysis and correlation methods are applied to analyze the spatiotemporal characteristics of ET and the relationship between ET and its driving factors using remotely sensed ET data and measured climate data between 2001 and 2018. During the study period, high values of ET primarily occurr in the wetlands of the plain area and the mid‐elevation mountain areas. The ET values show a significantly increasing trend in the different vegetation types due to climate change and other factors. The ET change trend in the study area is in the range of ?13.4 to ≈35.9 mm per year; the desert area exhibits a significant decrease and most of the mountain areas show a significantly increasing trend. ET is significantly correlated with land surface temperature, normalized difference vegetation index (NDVI), and solar radiation. The dominant factor affecting ET is NDVI, accounting for 15.2% of the study area. The results of this study highlight the need for appropriate land‐use strategies for managing water resources in arid land ecosystems.     

Investigation of the impacts of vegetation distribution and evaporative cooling on synthetic urban daytime climate using a coupled LES—LSM model

Local flow properties and regional weather or climate are strongly affected by land‐atmosphere interactions of momentum and scalars within the daytime convective boundary layer (CBL). In this study, we investigate the impact of green space scale on the daytime atmospheric boundary layer (ABL) over a synthetic urban domain using a recently developed large‐eddy simulation‐land surface model (LES–LSM) framework. With the use of realistic soundings as initial conditions, a series of numerical experiments over synthetic urban surfaces with varied scale of vegetated area is performed. Simulated micrometeorological properties, surface fluxes, basic CBL characteristics, and cloud distribution are analysed. The results show reference‐level air potential temperature and specific humidity as well as surface fluxes over green space are significantly affected by the scale of green space in the urban domain. The surface organization due to vegetated area scale also has impacts on horizontally averaged scalar and momentum profiles; however, the magnitude in this study is smaller than the results of a previous study using a set of offline surface fluxes as the lower boundary condition for LES. In addition, even though this study only performs a daytime diurnal cycle, the impact of green space scale on cloud distribution in simulations is significant. The cases with more organized green space yield lower‐elevated cumulus cloud and larger‐cloud cover fraction, which impacts the energy budget at the top of boundary layer and, in turn, could lead to additional surface cooling with respect to longer‐term weather and climate. Copyright © 2010 John Wiley & Sons, Ltd.     

Impacts of future land cover and climate change on the water balance in northern Iran

We evaluated the potential impacts of future land cover change and climate variability on hydrological processes in the Neka River basin, northern Iran. This catchment is the main source of water for the intensively cultivated area of Neka County. Hydrological simulations were conducted using the Soil and Water Assessment Tool. An ensemble of 17 CMIP5 climate models was applied to assess changes in temperature and precipitation under the moderate and high emissions scenarios. To generate the business-as-usual scenario map for year 2050 we used the Land Change Modeler. With a combined change in land cover and climate, discharge is expected to decline in all seasons except the end of autumn and winter, based on the inter-model average and various climate models, which illustrated a high degree of uncertainty in discharge projections. Land cover change had a minor influence on discharge relative to that resulting from climate change.     

Determination of regional land surface heat fluxes over a heterogeneous landscape of the Jiddah area of Saudi Arabia by using Landsat‐7 ETM data

In this study, a parameterization method based on Landsat‐7 Enhanced Thematic Mapper (ETM) data and field observations is presented and tested for deriving the regional land surface variables, vegetation variables and land surface heat fluxes over a heterogeneous landscape. As a case study, the method and two Landsat‐7 ETM images are applied to the Jiddah area of Saudi Arabia. The regional distribution maps of surface reflectance, normalized difference vegetation index, modified soil adjusted vegetation index (MSAVI), vegetation coverage, leaf area index, surface temperature, net radiation flux, soil heat flux, sensible heat flux and latent heat flux have been determined over the Jiddah area. The derived results have been validated by using the ‘ground truth’. The results show that the more reasonable regional distributions of land surface variables (surface reflectance, surface temperature), vegetation variables (MSAVI and vegetation coverage), net radiation, soil heat flux and sensible heat flux can be obtained by using the method proposed in this study. Further improvement of the method is also discussed. Copyright © 2006 John Wiley & Sons, Ltd.     

On the faults of western Hexi Corridor and its nearby regions, northwestern China:Thrust faults and strike-slip faults of Late Cenozoic

Introduction Hexi Corridor, a corridor extended over 1 000 km and with a strike of WNW-ESE, is locatedbetween Alxa uplift and northern Qilianshan Caledonian folding belt of northern Qinghai-Xizang(Tibet) Plateau (Figure 1). In the paper, we will discuss the regions between Altun fault and Yu-mushan of the western Hexi Corridor, where the climate is arid, which results in sparse vegetation,but abundant oil and gas resource, and being one of the most important petroleum industry base…     

城市化对四川盆地夏季气温变化影响的观测和模拟研究

城市化引起的气温上升是土地覆盖变化影响区域气候的重要体现.本文采用"观测资料减去再分析"(Observation Minus Reanalysis,OMR)的方法估计四川盆地和周边地区下垫面城市化改变对夏季地面2 m气温变化趋势的影响.设计了不同城市化下垫面扩展变化的WRF模拟试验,对1998-2012年四川盆地及周边...     

Improvement of the Noah land surface model for warm season processes: evaluation of water and energy flux simulation

The Noah model is a land surface model of the National Centers for Environmental Prediction. It has been widely used in regional coupled weather and climate models (i.e. Weather Research and Forecasting Model, Eta Mesoscale Model) and global coupled weather and climate models (i.e. National Centers for Environmental Prediction Global Forecast System, Climate Forecast System). Therefore, its continued improvement and development are keys to enhancing our weather and climate forecast ability and water and energy flux simulation accuracy. North American Land Data Assimilation System phase 1 (NLDAS‐1) experiments indicated that the Noah model exhibited substantial bias in latent heat flux, total runoff and land skin temperature during the warm season, and such bias can significantly affect coupled weather and climate models. This paper presents a study to improve the Noah model by adding model parameterization processes such as including seasonal factor on leaf area index and root distribution and selecting optimal model parameters. We compared simulated latent heat flux, mean annual runoff and land skin temperature from the Noah control and test versions with measured latent heat flux, land surface skin temperature, mean annual runoff and satellite‐retrieved land surface skin temperature. The results show that the test version significantly reduces biases in latent heat, total runoff and land skin temperature simulation. The test version has been used for the NLDAS phase 2 (NLDAS‐2) to produce 30‐year water flux, energy flux and state variable products to support the US drought monitor of National Integrated Drought Information System. Copyright © 2012 John Wiley & Sons, Ltd.     

太湖流域空间开发适宜性分区与失衡性评估

随着发达地区经济社会的快速发展,建设用地急剧扩张,改变地表下垫面水文条件,成为导致区域水环境不断恶化的重要因素,并引发一系列的资源环境问题.为了促进资源环境与经济社会均衡发展,近年来地理学界开展了大量空间开发功能分区和适宜性分区的研究,为区域空间管理和建设用地调控提供科学依据,但是这些研究大多以单一行政区为对象,缺少流域等跨行政区的自然地理单元的分区研究,忽视了流域经济社会发展与资源环境保护的整体性.为此,本文在借鉴相关分区研究的基础上,以太湖流域为例,探讨了流域单元空间开发适宜性分区指标选择与综合评价等技术方法,将太湖流域划分为高适宜区、中等适宜区、低适宜区和不适宜区等四种类型,并采用数据包络分析方法,探讨了建设用地配置规模与空间开发适宜性的对应关系和均衡程度,据此判断流域空间开发的失衡状态.     

甘肃省河西地区高层建筑动力特性脉动观测研究

采用脉动观测方法对甘肃省河西地区的武威皇台大厦,张掖电力大厦和张掖国税大厦３栋高层建设的自振特性进行测试。在分析３栋建筑的自振周期、振型和阻尼比时,结合对当地场地特性的分析,指出了河西地区对高层建设有利的场地条件以及今后在该地区修建以建筑时应注意的若干问题。     

河西走廊4200年以来青铜冶炼的元素地球化学记录

金属的使用与冶炼是人类社会发展过程中一项革命性事件。河西走廊地区全新世条湖湖相沉积元素地球化学记录显示,10500-9500cal aBP和8000-7200cal aBP时段Cu、Pb、Zn、Ni元素含量高值区,分别对应了早全新世增温期冰川融水量增加和全新世适宜期季风降水的增强。Cu、As、Pb、Zn、Ni含量在4200-3700cal aBP时段出现最高峰值,另外Cu、Pb、Zn、Ni4种元素在3000-2700和2100-1900cal aBP时段出现较高峰值。4200-3700cal aBP时段元素异常记录了我国西北地区最早的青铜冶炼,As元素是这一时期青铜合金的主要成份。另外,西周时期(3000-2700cal aBP)和汉代(2100-1900cal aBP)Cu、Pb、Zn、Ni元素峰值,可能是先民青铜冶炼的结果。元素地球化学记录不仅可以判定早期青铜冶炼的起迄时间,也提供了甄别不同时代青铜合金元素组成变化的信息。