Temporal and Spatial Characteristics of Climate Changes in the Urumqi River Basin of Tianshan Mountain over 50 years

Based on the meteorological data during 1959-2008 from five representative weather stations in the Urumqi River Basin and surrounding areas,the regional characteristics of temperature and precipitation in the basin featuring multi-climatic zones were studied by means of some methods including wavelet analysis.As was shown in the results,the temperature in the whole Urumqi River Basin demonstrated a significant upward trend.The temperature increase particularly in autumn and winter made the greatest contribution to the marked ascent.The interdecadal temperature in the basin showed a tendency to decline before the period during 1970s-1980s while it was on the rise after 1990s on the whole.The most concentrated period of temperature mutations was in the late 1990s.At the same time,the precipitation also showed an escalating trend,which experienced a stage of unanimous upward trend after 1990s.The most concentrated period of precipitation mutations was in the early 1990s.

Hydrological effects of alpine permafrost in the headwaters of the Urumqi River,Tianshan Mountains

Against the background of climate change, alpine permafrost active layers have shown a gradual thickening trend and the hydrothermal conditions have undergone significant changes in the Tianshan Mountains and the Qinghai-Tibet Plateau, China. At the ice-free cirque basins in the headwaters of the Urumqi River （hereafter referred to as the Ice-Free Cirque） in eastern Tianshan, China, the hydrological effects of the alpine permafrost active layers appear to have also exhibited sig- nificant changes recently. The increasing trend of local precipitation is clear in May and June. The onset of winter and spring snowmelt runoff clearly lags behind increases of air temperature, and the runoff peak appears near the beginning of the melting season, which results in the spring rtmoff increasing. In summer, runoff decreases strongly and the maximum runoff occurs earlier. In our analysis of meteorological and hydrologic data from 1959 to 2010, the runoffand precipitation changes are significantly correlated. In the initial stage of runoff, the runoff-producing process is mainly under the control of the soil water content and soil temperature in the 0-30 cm active layers. Spring precipitation and snowmelt water are mainly involved in the processes of infiltration and evaporation while some melt water infiltrates into the seasonal thawed layer and stays above the frozen layers. During the strong ablation period in summer, the runoff-generating process is mainly controlled by soil water content in the active layers deeper than 60 cm. In the active layer, precipitation and sea- sonal snowmelt water infiltrates, migrates, collects, and then forms runoff.

Study on diversity and temporal-spatial characteristics of eukaryotic microorganisms on Glacier No.1 at the Urumqi River Head,Tianshan

Surface snow samples of different altitudes and snow pit samples were collected from Glacier No. 1 at the Urumqi River Head, Tianshan. Denaturing gradient gel electrophoresis （DGGE） was used to examine the diversity and temporal-spatial characteristics of eukaryotic microorganisms with different altitudes and depths. Results show that the eukaryotic microorganisms belong to four kingdoms--Viridiplantae, Fungi, Amoebozoa, and Alveolata. Among them, algae （especially Chlamydomonadales） were the dominant group. The diversity of eukaryotic microorganisms was negatively correlated with altitude and accumulation time, but positively correlated with 8180 values. These results indicate that temperature is the main factor for the temporal-spatial change of eukaryotic microorganisms, and the diversity of eukaryotic microorganisms could be an index for climate and environmental change.

Snowmelt modeling using two melt-rate models in the Urumqi River watershed, Xinjiang Uyghur Autonomous Region, China

In this paper,the performance of the classic snowmelt runoff model(SRM)is evaluated in a daily discharge simulation with two different melt models,the empirical temperature-index melt model and the energy-based radiation melt model,through a case study from the data-sparse mountainous watershed of the Urumqi River basin in Xinjiang Uyghur Autonomous Region of China.The classic SRM,which uses the empirical temperature-index method,and a radiation-based SRM,incorporating shortwave solar radiation and snow albedo,were developed to simulate daily runoff for the spring and summer snowmelt seasons from 2005 to 2012,respectively.Daily meteorological and hydrological data were collected from three stations located in the watershed.Snow cover area(SCA)was extracted from satellite images.Solar radiation inputs were estimated based on a digital elevation model(DEM).The results showed that the overall accuracy of the classic SRM and radiation-based SRM for simulating snowmeltdischarge was relatively high.The classic SRM outperformed the radiation-based SRM due to the robust performance of the temperature-index model in the watershed snowmelt computation.No significant improvement was achieved by employing solar radiation and snow albedo in the snowmelt runoff simulation due to the inclusion of solar radiation as a temperature-dependent energy source and the local pattern of snowmelt behavior throughout the melting season.Our results suggest that the classic SRM simulates daily runoff with favorable accuracy and that the performance of the radiation-based SRM needs to be further improved by more ground-measured data for snowmelt energy input.

Isotopic evidence for the moisture origin and influencing factors at Urumqi Glacier No.1 in upstream Urumqi River Basin, eastern Tianshan Mountains

The stable isotope has been extensively applied as an effective tracer especially in precipitation. In glacierized area of arid northwest China, temperature is widely considered to be a major factor affecting isotopes in precipitation, while the influences of precipitation amount, relative humidity and other meteorological parameters are still not clear. Based on analyses on stable isotope values of water samples and NCEP/NCAR(National Centers of Environmental Prediction/National Center for Atmospheric Research, USA) re-analysis data, the moisture source and characteristics of isotopes in the precipitation, meltwater and river water isotopes at Urumqi Glacier No.1 of the upstream Urumqi River Basin, eastern Tianshan Mountains from spring to autumn during four years(from 2008 to 2011) was studied. Results indicated that meltwater are the main source of water for the upper Urumqi River. Seasonal variation of δ18 O in precipitation demonstrated that δ18 O was more enriched in summer and depleted in spring and autumn. Temperature was positively correlated with isotopes, while precipitation amount and relative humidity was negatively correlated with isotopes. The water vapor was affected by westerly air mass and regional water vapor cycle. Meanwhile, back trajectory clustering analyses showed that the moisture mainly from Europe and central Asia. The moisture was more likely to be locally sourced with the ratio was 46.8%~52.1%.

Variations and future projections of glacial discharge of Urumqi River Headwaters,eastern Tien Shan(1980s-2017)

To address data scarcity on long-term glacial discharge and inadequacies in simulating and predicting hydrological processes in the Tien Shan,this study analysed the observed discharge at multiple timescales over 1980se2017 and projected changes within a representative glacierized high-mountain region:eastern Tien Shan,Central Asia.Hydrological processes were simulated to predict changes under four future scenarios(SSP1,SSP2,SSP3,and SSP5)using a classical hydrological model coupled with a glacier dynamics module.Discharge rates at annual,monthly(June,July,August)and daily timescales were obtained from two hydrological gauges:Urumqi Glacier No.1 hydrological station(UGH)and Zongkong station(ZK).Overall,annual and summer discharge increased significantly(p<0.05)at both stations over the study period.Their intra-annual variations mainly resulted from differences in their recharge mechanisms.The simulations show that a tipping point in annual discharge at UGH may occur between 2018 and 2024 under the four SSPs scenarios.Glacial discharge is predicted to cease earlier at ZK than at UGH.This relates to glacier type and size,suggesting basins with heavily developed small glaciers will reach peak discharge sooner,resulting in an earlier freshwater supply challenge.These findings serve as a reference for research into glacial runoff in Central Asia and provide a decision-making basis for planning local water-resource projects.

Economic value of freshwater provisioning services of the cryosphere in the Urumqi River, Northwest China

As an important component of cryospheric provisioning services, freshwater provisioning services of the cryosphere is particularly critical to human well-being and socio-economic sustainability. It is imperative to quantitatively estimate the value of freshwater provisioning services to facilitate informed decision-making for ecosystem management and economic development. This study assessed the economic value and associated changes in benefits of freshwater provisioning services for industrial, agricultural, services and domestic water uses combining cost-based method and hydrological model in the Urumqi River during 2010–2016. The results showed that the average annual economic value of agricultural, services, domestic and industrial water uses generated from freshwater provisioning services were estimated to be 1.7, 4.4, 9.9, and 15.7 million CNY. The annual value of snowmelt provisioning services of sectorial water uses was much higher than that of glacier meltwater due to the greater contribution of snowmelt to outlet streamflow than glacier melt. The relative contributions of agricultural, services, domestic and industrial sectors to total economic value of freshwater provisioning services were 6%, 13%, 32%, and 49% respectively, depending on the meltwater supply and market prices. The benefits of freshwater provisioning services from different sectors generally increased in 2010–2016, with a significant increase in the services sector. Considering the impact of changes in freshwater supply under climate change on the assessment of cryospheric provisioning services, the results emphasize the necessity of promoting industrial structure optimization and adopting resource-efficient policies.

Sensitivity of mountain runoff to climate change for Urumqi and Kaidu rivers originating from the Tianshan Mountains

The mountain watersheds of Kaidu River and Urumqi River, which separately originate from the south and north-side of the Tianshan Mountains in Xinjiang, are selected as the study area. The characteristics and trends on variation of temperature, precipitation and runoff, and the correlativity between temperature, precipitation, and runoffwere analyzed based on the past 40 years of observational data from the correlative hydrological and weather stations in the study areas. Various weather scene combinations are assumed and the response models of runoff to climate change are established in order to evaluate the sensitivity of runoff to climate change in the study areas based on the foregoing analysis, Results show that all variations of temperature, precipitation, and runoff overall present an oscillating and increasing trend since the 1960s and this increase are quite evident after 1990. There is a markedly positive correlation between mountain runoff, temperature, and precipitation while there are obvious regional differences of responding degree to precipitation and temperature between mountain runoff of Ummqi River and Kaidu River Basins Also, mountain runoff of Urumqi River Basin is more sensitive to precipitation change than that of Kaidu River Basin, and mountain runoff of Kaidu River Basin is more sensitive to temperature change than that of Ummqi River Basin.

PRELIMINARY RESEARCHES ON LICHENOMETRIC CHRONOLOGY OF HOLOCENE GLACIAL FLUCTUATIONS AND ON OTHER TOPICS IN THE HEADWATER OF URUMQI RIVER, TIAN-SHAN MOUNTAINS

This paper introduced briefly the research results on lichenometry of the Holoceneglacial fluctuations in the headwater of the Urumqi River, in the central TianshanMountains and discussed the histories of the Holocene glaciers and the climate. It isconsidered that lichenometry is one applicable method for dating the mid- and late-Holocene deposits in the cold and mountainous regions. Rhizocarpon geographicum (L.)DCand Xanthoria elegans (Link.) Th. Fr. could be used for dating the deposits of about 4500and 500 a B.P. respectively. There existed at least four periods of glacial advances whichoccurred before about 5700, 4100, 2800 and 403- 74 a B. P. respectively with the firstperiod the longest. Little Ice Age includes three stages of glacial advances which endedbefore about 403, 208 and 74 a B. P. respectively with the second stage the maximum.During the general Holocene warming processes, there existed at least four cold peri-ods which ended before about 5700, 4100, 2800 and 420- 91 a B.P. respectively, the averageair temperatures of which were about 1.5, 1.25, 0.9 and 0.65℃ higher than the presentone respectively with the warm periods in between. The amplitude of air temperaturechanges is about 2.5℃.

Preliminary studies on the ionic pulse of snowmelt runoff in the Urumqi River, Xinjiang, Northwest China

IONIC pulse of snowmelt and its runoff in seasonally snow-covered alpine catchments was de-fined by Johannessen et al. When a snowpack begins melting, the first meltwater drainingthrough the pack carries a large fraction of the soluble ions with it, an ionic pulse. 10％ of thefirst meltwater may drain 80％ of the soluble contents out of the snowpack within severalhours or days. In other words, an ionic pulse designates a peak in ionic concentration duringthe initial melting process of a snowpack. The peak has been proved by a plot test 10 times

Environmental changes in the upper-reaches of Thurumqi River in the past 10,000 years, Tianshan Mountains, China

The sediments, at bore-hole T-3 in the upper reaches of the Urumqi River, are 10.7 mthick, and are composed mainly of till, slope-washed materials, solifluction and glacial-waterdeposits. The borehole can be divided into six sections based on the pollen distribution, magneticsusceptibility , δ13C determinations and the diatoms distribution. There were three cold and dryperiods during the past 10.0 Ka （103 years）: before 9.3 KaBP, from 8.1 to 5.6 KaBP and 3.0 to 1.0KaBP. The three warmer periods were from 9.3 to 8.1 KaBP, 5.6 to 3.0 KaBP and since 1.0 KaBP.The Holocene maximum was between 5.6 and 3 KaBP. However, the vegetation compositions,mainly C3 plants, the magnetic susceptibility and the δ13C were little changed in the study region inthe past 10 Ka. Indications are that the climate was relatively cold and stable during the past 10Ka.

不同情景下乌鲁木齐河流域土地利用动态模拟研究

收集2000、2010、2020年乌鲁木齐河流域土地利用/覆被变化等数据,通过多评价准则(MCE)的元胞自动机(CA)和马尔可夫链(Markov)模型,对2020年土地利用变化进行模拟,预测结果与实际解译结果对比,各土地利用类型的面积预测精度达到82%以上,空间格局kappa系数平均值为81.57,表明预测结果可信。在此基础上,在不同场景下对2030年的土地利用空间格局进行模拟,结果表明,在趋势发展情景下,耕地、草地面积呈减少趋势,分别为15.1%和5.22%,建设用地、未利用地面积增幅较大,分别为26.09%和21.15%,表明按照当前城市扩张速度和产业结构布局方式发展,生态用地与建设用地需求的矛盾将日益突出,生态环境面临巨大挑战。在生态优先情景下,建设用地面积增幅减缓至18.03%,耕地、林地、水域面积呈上升趋势,分别为10.26%、2.36%和11.11%,草地面积下降趋势减缓至3.55%,表明城市快速扩张得到遏制,耕地得到保护,林地、草地能够发挥更大的生态调节作用,水源的涵养能力有所提升,土地利用结构变化趋于均衡。

Glacier mass balance and its impacts on streamflow in a typical inland river basin in the Tianshan Mountains, northwestern China

Glaciers are known as natural ’’solid reservoirs’ ’, and they play a dual role between the composition of water resources and the river runoff regulation in arid and semi-arid areas of China. In this study, we used in situ observation data from Urumqi Glacier No. 1, Xinjiang Uygur Autonomous Region, in combination with meteorological data from stations and a digital elevation model, to develop a distributed degree-day model for glaciers in the Urumqi River Basin to simulate glacier mass balance processes and quantify their effect on streamflow during 1980–2020. The results indicate that the mass loss and the equilibrium line altitude(ELA) of glaciers in the last 41 years had an increasing trend, with the average mass balance and ELA being-0.85(±0.32) m w.e./a(meter water-equivalent per year) and 4188 m a.s.l., respectively. The glacier mass loss has increased significantly during 1999–2020, mostly due to the increase in temperature and the extension of ablation season. During 1980–2011, the average annual glacier meltwater runoff in the Urumqi River Basin was 0.48×108 m3, accounting for 18.56% of the total streamflow. We found that the annual streamflow in different catchments in the Urumqi River Basin had a strong response to the changes in glacier mass balance, especially from July to August, and the glacier meltwater runoff increased significantly. In summary, it is quite possible that the results of this research can provide a reference for the study of glacier water resources in glacier-recharged basins in arid and semi-arid areas.

乌鲁木齐河分洪工程引水枢纽施工导流设计

引水枢纽是乌鲁木齐河分洪工程的重要组成部分,是位于关键线路上的重点施工项目,采用科学合理的施工导流方案是确保引水枢纽顺利施工的前提。通过分析引水枢纽所处河段的地形、地质和水文条件,结合水工建筑物布置和施工工期要求,最终确定施工导流采用分期导流的方式,导流标准采用10a 1遇洪水,围堰采用当地材料填筑,施工导流方案的确定为工程整体效益的发挥奠定了基础。

高寒山区固态降水观测对比研究

降水类型变化是深入理解全球变暖背景下陆地水循环演变的重要内容,高寒山区降水类型观测研究一直是国内外学者关注的热点和难点问题。本文选用2018年5月至2020年4月乌鲁木齐河源1号冰川末端的PWS100激光雨滴谱仪和Geonor T-200B称重式雨雪量计的同步降水观测数据进行对比研究。结果表明:(1)PWS100观测结果显示该试验场以固态降水为主,固体颗粒物占总颗粒物的63%,液体颗粒物占总颗粒物的37%;月尺度上,6-8月粒子数量最多,其中液态粒子占57%,固态粒子43%。其余月份以固态粒子数为主,占总粒子数的96%。(2)基于降水粒子在不同温度区间所占比重,以气温6.5℃为临界值划分降水类型。修正后T-200B降雨总累积量为1202 mm,占DFIR的67%,低估了降水量,但平均相对捕获率达到了87%。(3)两台仪器观测的降水总量大致相同(仅相差71 mm),然而,季节性差异明显,6-8月PWS100比T-200B高出73 mm,9月至次年5月则少37 mm。PWS100在降水量大、降水类型复杂的夏季,观测到的降水量大,而冬季降水量较少,且PWS100对小雨滴不敏感,会导致捕获量的不足,因此,T-200B在捕获固态降水方面更有效。研究结果为进一步研究变暖背景下山区流域径流季节变化提供了实验基础。

西北干旱区乌鲁木齐河流域植被生长季降水特征分析

根据乌鲁木齐河流域7个国家气象站和20个自动气象站2013—2021年植被生长季(5—9月)逐日降水量资料,分析植被生长季乌鲁木齐河流域降水量、降水日数、不同量级降水及其贡献率随海拔变化特征,以期为流域的水资源利用、生态环境治理及保护提供一定参考。结果表明:乌鲁木齐河流域植被生长季降水量和降水日数均随海拔升高呈波动增加趋势,分别以17.4 mm·(100 m)^(-1)、2.85 d·(100 m)^(-1)速率增加,其中生长季降水量以海拔1 000 m左右为分界,海拔依赖性由弱转强,在海拔约1 200 m和2 000 m出现降水高值带,并且降水高值带呈现由低海拔山地逐渐抬升至中高山带而后回落的变化规律;降水日数高值地带始终在中高山带(海拔高于1 800 m),且具有较强稳定性。植被生长季降水日数与降水量的月际特征有较好的一致性,均随海拔升高而增加,海拔2 200 m以下区域,6月的降水量和7月的降水日数随海拔升高增速最显著,分别以4.8 mm·(100 m)^(-1)、0.72 d·(100 m)^(-1)的速率增加,二者均在9月增速最不显著,分别为1.1 mm·(100 m)^(-1)、0.37 d·(100 m)^(-1)。流域植被生长季仅小雨、中雨和大雨发生次数具有较强的海拔依赖性且不同强度降水的贡献率与海拔无明显关联。

新疆乌鲁木齐河分洪工程坝体静、动力计算分析

鉴于乌鲁木齐河分洪工程属大(2)型Ⅱ等工程,其主要任务为防洪。为保证坝体安全超高的合理性,通过建立二维有限元模型,对该工程渠首坝体进行静、动力计算分析,采用邓肯张E-B静力本构模型和等效黏弹性动力本构模型,分析坝体变形的合理性及永久变形量,为安全超高提供合理依据。结果表明:各个工况下坝体位移不大均小于规范1%沉降量范围,根据计算结果并参考同类大坝沉降情况,初步确定坝顶预留沉降超高按照相应坝段坝高的1%加高,坝顶高程最大增加高度6cm,可满足设计要求。

乌鲁木齐河流域地质生态环境变化趋势研究

通过在乌鲁木齐河流域开展山水林田湖草沙生态修复工程前期调查工作,分析乌鲁木齐河流域内土壤盐渍化、土地荒漠化、湿地的分布现状;分析2000—2020年轻度、中度、重度土壤盐渍化、土地荒漠化的分布变化特征、演变趋势、湿地分布变化特征及演变趋势;分析引起土壤盐渍化、土地荒漠化、湿地功能退化的原因。通过遥感解译及现场调查验证表明,自2000—2020年,乌鲁木齐河流域内轻度、中度、重度盐渍化面积,呈先增大后减少变化的趋势;轻度、中度、重度荒漠化面积呈持续减少的变化趋势;湿地面积呈快速下降趋势。

乌鲁木齐河流域不同水体中的氧稳定同位素

采用乌鲁木齐河流域历年采集的降水、表层粒雪、冰川融水和河川径流等水样资料,分析了取样期间不同水样中氧稳定同位素的变化,揭示了降水中氧稳定同位素变化存在着明显的温度效应,而温度效应又与海拔高度有关;表层粒雪和冰川融水中氧稳定同位素则无明显的高度效应;冰川融水中的氧稳定同位素比率小于河川径流中的氧稳定同位素比率。评估了不同影响因子对水循环过程中稳定同位素变化的影响及相互作用,为稳定同位素技术在水循环研究中的应用提供了实例。

天山乌鲁木齐河源1号冰川物质平衡对气候变化的敏感性研究

应用度日物质平衡模式对天山乌鲁木齐河源１号冰川物质平衡及平衡线高度对气候变化的敏感性进行了研究．结果表明，位于大陆性气候区且具有暖季补给特征的乌鲁木齐河源１号冰川物质平衡对气候变化的敏感性要小于海洋性冰川，升温１℃或增加２０％的降水可引起平衡线上升８１ｍ或下降３１ｍ．此外，气温与降水在物质平衡形成过程中的作用是不同的，气温引起物质平衡剖面以旋转方式变化，而降水可导致其平移方式的响应．若未来升温２℃时，即使降水增加３０％，１号冰川向负平衡变化仍然不能得到遏制．