Association of North Atlantic Oscillations with Aksu River runoff in China

The relationship between North Atlantic Oscillations （NAO） and Aksu River Runoff （ARR） was investigated by using the wavelet transform （WT）, cross wavelet transform （CWT）, correlation and linear trend analyses, and abrupt change test. The main results are as follows the interannual/decadal variation and period analyses of ARR and NAO reveal that the both were close correlated each other; the CWT indicates that the correlation was good between ARR and NAO at all periods in the 1990s, because the significant correlation areas mainly concentrated in the 1990s; the variations in the trend strength of ARR and NAO were consistent; the abrupt change of NAO was also temporally consistent with that of ARR, which exerted impact on the Aksu River Basin （ARB） climate and then the ARR through atmospheric circulation variation.

Application of hydrological models in a snowmelt region of Aksu River Basin

This study simulated and predicted the runoff of the Aksu River Basin, a typical river basin supplied by snowmelt in an arid mountain region, with a limited data set and few hydrological and meteorological stations. Two hydrological models, the snowmelt-runoff model （SRM） and the Danish NedbФr-AfstrФmnings rainfall-runoff model （NAM）, were used to simulate daily discharge processes in the Aksu River Basin. This study used the snow-covered area from MODIS remote sensing data as the SRM input. With the help of ArcGIS software, this study successfully derived the digital drainage network and elevation zones of the basin from digital elevation data. The simulation results showed that the SRM based on MODIS data was more accurate than NAM. This demonstrates that the application of remote sensing data to hydrological snowmelt models is a feasible and effective approach to runoff simulation and prediction in arid unguaged basins where snowmelt is a major runoff factor.

MODIS observed snow cover variations in the Aksu River Basin, Northwest China

A major proportion of discharge in the Aksu River is contributed from snow-and glacier-melt water.It is therefore essential to understand the cryospheric dynamics in this area for water resource management.The MODIS MOD10A2 remotesensing database from March 2000 to December 2012 was selected to analyze snow cover changes.Snow cover varied significantly on a temporal and spatial scale for the basin.The difference of the maximum and minimum Snow Cover Fraction(SCF)in winter exceeded 70%.On average for annual cycle,the characteristic of SCF is that it reached the highest value of 53.2%in January and lowest value of 14.7%in July and the distributions of SCF along with elevation is an obvious difference between the range of 3,000 m below and 3,000 m above.The fluctuation of annual average snow cover is strong which shows that the spring snow cover was on the trend of increasing because of decreasing temperatures for the period of 2000-2012.However,temperature in April increased significantly which lead to more snowmelt and a decrease of snow cover.Thus,more attention is needed for flooding in this region due to strong melting of snow.

Hydrological processes in the Aksu River source region during the intense ablation period based on water chemistry and isotopes

Against the backdrop of global warming,the dynamics of glaciers and their water resources have significant implications for hydrological processes in the arid regions of Northwest China.The Aksu River,which is an essential inland river enriched by substantial meltwater contributions,plays a pivotal role in the economic,ecological,and social development of the region.Based on 231 water samples collected during the period of intense glacial ablation in 2023,this study conducted a comprehensive analysis of the hydrochemical and stable isotopic characteristics of the Little Kurgan glacial basin in the Aksu River source region.A Piper diagram classified the hydrochemical type of the river water as Calcium-Bicarbonate.Analysis based on a Gibbs diagram indicated that rock weathering is the predominant factor affecting the hydrochemical properties within the studied basin.Through application of principal component analysis and end-member mixing analysis,it was determined that the glacier meltwater contribution to runoff was 67%,61%,and 55%in July,August,and September,respectively.The findings of this study reveal that glacier meltwater is the principal component of the river water,and highlight the critical impact of alterations in glacier ablation on the hydrological cycle within the Aksu River source region,which is vitally important for sustainable water resource management.

Assessing the impact of climate change on potential evapotranspiration in Aksu River Basin

Evapotranspiration is one of the key components of hydrological processes. Assessing the impact of climate factors on evapotranspiration is helpful in understanding the impact of climate change on hydrological processes. In this paper, based on the daily meteorological data from 1960 to 2007 within and around the Aksu River Basin, reference evapotranspiration （RET） was estimated with the FAO Penman-Monteith method. The temporal and spatial variations of RET were analyzed by using ARCGIS and Mann-Kendall method. Multiple Regression Analysis was employed to attribute the effects of the variations of air temperature, solar radiation, relative humidity, vapour pressure and wind speed on RET. The results showed that average annual RET in the eastern plain area of the Aksu River Basin was about 1100 mm, which was nearly twice as much as that in the western mountainous area. The trend of annual RET had significant spatial variability. Annual RET was reduced significantly in the southeastern oasis area and southwestern plain area and increased slightly in the mountain areas. The amplitude of the change of RET reached the highest in summer, contributing most of the annual change of RET. Except in some high elevation areas where relative humidity predominated the change of the RET, the variations of wind velocity predominated the changes of RET almost throughout the basin. Taking Kuqa and Ulugqat stations as an example, the variations of wind velocity accounted for more than 50% of the changes of RET.

Glacier changes from 1975 to 2016 in the Aksu River Basin, Central Tianshan Mountains

In this study, we analyzed glacier changes in the Aksu River Basin during the period 1975–2016, based on Landsat MSS/TM/ETM+/OLI imagery analysis and the Chinese Glacier Inventory(CGI). The results showed that the total number, area, and volume of the studied glaciers in the Aksu River Basin decreased by 202(7.65%), 965.7 km^2(25.88%), and 74.85–78.52 km^3(23.72%–24.3%), respectively. The rate of glacier retreat in the basin was slower in the north, northwest and west, but reached the highest in the east(measuring 0.86% yr^(-1)). Furthermore, there were significant regional differences in the distribution and change of glaciers, the Kumalak River Basin had the largest glacier number and area, about 63.15% and 76.47% of the studied basin, and the rate of glacier retreat in the Kumalak River Basin was 0.65% yr^(-1), it was higher than the Toxkan River Basin which reached 0.57% yr^(-1). We found the shrinkage rate of glacier for different periods in the past 41 years, during 1975–1990 the glaciers showed the greatest retreat, while the rate of glacier area retreat slowed down significantly from 1990 to 2000. In recent 16 years since 2000, the rate of glacier retreat in the Toxkan River Basin was higher compared with 1990–2000. The RGI50^(-1)3.04920 glacier of Kumalak River Basin had been in a state of retreat since 1990. Over the past 41 years, the temperature and precipitation in the Aksu River Basin increased obviously, and the warming temperatures were clearly the main reason for glacier retreat in the region, while the increased precipitation in the mountain area may have a direct relation with the retreating rate of glaciers.

2000—2020年阿克苏河流域植被动态变化及驱动机制

[目的]探究阿克苏河流域植被动态特征及其与潜在影响因子的响应关系,为干旱区生态环境保护和治理提供理论依据。[方法]基于MODIS归一化植被指数(NDVI)、气候、地形、土壤类型及土地利用等数据,利用趋势分析和地理探测器方法对2000—2020年阿克苏河流域植被动态及驱动机制进行分析。[结果]①2000—2020年阿克苏河流域NDVI呈显著增加趋势,增速为0.0032/a,且人类活动区增速显著大于非人类活动区。②潜在因子对NDVI变化的解释力存在时间和空间差异;土地利用转化是人类活动区NDVI变化重要驱动因子,海拔、土壤类型、距冰川积雪距离、距水体距离是非人类活动区NDVI变化重要驱动因子。因子间交互作用可以提高对NDVI变化的解释力,在人类活动区土地利用转化与土壤类型的相互作用对NDVI变化的解释力最强;背景因子、距补给水源的距离与其他因子的交互是非人类活动区NDVI变化的重要因子组合。③2000—2020年阿克苏河流域超过10%的面积发生土地利用转化,主要表现为裸地和草地的相互转化,耕地、林地、灌木地、人造地表面积显著增加。[结论]阿克苏河流域人类活动区和非人类活动区NDVI变化时空特征及驱动机制存在差异,应因地制宜,合理管理,促使该流域生态环境良性发展。

40年来新疆阿克苏河流域地下水流场演化及成因模式

西北干旱内陆河流域经历了水土资源的大规模开发,对区域地下水和生态环境产生重要影响,但地下水长期演化机制认识尚不够清晰。本研究以新疆阿克苏河流域为典型区,通过最新地下水位数据和历史数据对比,分析流域地下水流场和埋深时空变化历史过程、特征及成因模式,探讨该区地下水长期演化与土地利用变化之间的关系,揭示人类活动影响下的地下水演化机制。结果表明:1979年以来,随着耕地面积增加,区域地下水流场经历了近天然状态到人类活动强烈影响的历史过程,潜水位和承压水头均有不同程度下降,局部地区承压水流向以及与潜水的补排关系发生改变。承压水主要依靠侧向径流补给,但人工开采强度远远大于侧向补给量,导致承压水头明显下降。以研究区中部英艾日克乡-喀拉塔勒镇一线为界,北部地区潜水水位和承压水水头降幅均大于南部地区,原因在于土地利用变化造成地下水补排条件发生改变,北部地区潜水水质较好,被大量开采用于农业灌溉,而南部因地下水质较差,以引用地表水灌溉为主,地下水开采强度较低,因此南部地下水下降不如北部地区明显。研究成果可为新疆阿克苏河流域及类似地区地下水的可持续开发利用与生态保护提供科学依据。

基于PLUS土地利用模拟的阿克苏河流域NEP时空格局研究

净生态系统生产力(NEP)是评估陆地生态系统碳吸收量的重要指标,而土地利用/覆盖变化(LUCC)是影响区域碳吸收量变化的主要因素之一,分析LUCC与NEP的变化趋势,对区域实现“双碳”目标具有重要意义。基于阿克苏河流域2000—2020年LUCC与MODIS遥感数据估算区域内各土地利用/覆盖类型的年均固碳速率,借助PLUS模型模拟未来40 a的LUCC,预测未来40 a流域NEP时空变化趋势。结果表明:(1)近20 a流域内总NEP呈上升趋势,上升速率为0.136 Mt C·(10a)-1,林地平均固碳速率最高;(2)未来40 a阿克苏河流域总碳吸收量在不断上升。林地面积的增加是阿克苏河流域碳吸收量上升的主要途径,生态保护工程的积极性对流域内碳吸收量起到关键作用。

2000—2020年阿克苏河流域土地利用强度变化及其对蒸散发的影响

深入挖掘土地利用类型内部转换过程信息,衡量土地利用变化强度对蒸散发的影响,准确评估实际蒸散发时空变化规律对流域水资源科学管理和高效利用具有重要意义。基于强度分析模型揭示2000—2020年阿克苏河流域不同层次土地利用类型强度变化特征及对流域实际蒸散发的影响,结果表明:(1)时间间隔层次上流域土地利用变化强度呈先增加后减小的趋势,2000—2005年变化最为活跃。地类层次上耕地、建设用地、水域、林地面积增减变化表现较为活跃。转移层次上耕地面积的增加主要来源于草地(占比54.31%)和未利用地(占比26.26%);(2)流域多年平均蒸散发为166.56 mm。年际波动较大,整体呈增加趋势,年增长率为3.68 mm·a^(-1)。年内4—10月蒸散发占全年蒸散发的71.76%。实际蒸散发高值区分布在山区林地和平原区耕地,低值区分布在山前荒漠区及绿洲与荒漠过渡带地区;(3)主成分分析结果表明,阿克苏河流域实际蒸散发变化的驱动力为草地、耕地、未利用地的转化强度,土地利用变化强度与实际蒸散发之间的相关系数为0.87,二者存在较强的相关关系。

Processes and trends of the land use change in Aksu watershed in the central Asia from 1960 to 2008

Land use change (LUC) in trans-boundary watersheds is of great importance to environmental assessment. The Aksu River is the largest trans-boundary river crossing Kyrgyzstan and China,but there was little information on the LUC of the watershed. We quantitatively investigated the processes and trends of its LUC by using analytic models based on the land use data derived from the remote sensing images and topographic maps. The LUC was in the quasi-balanced status with a slight difference between the loss and the gain of the area for most land use types during the period of 1960-1990,whereas transferred to the unbalanced status with significant difference between the loss and gain of the area during the period of 1990-2008. At the same time,land conversion direction changed from two-way transition to one-way transition for the most land use types. The integrated rate of net change of land use during the period of 1990-2008 is 2.1 times of that during the period of 1960-1990. Information on the processes and trends of LUC is valuable for better understanding the environmental changes across the whole trans-boundary watershed,and helpful to decision-making management for Kyrgyzstan and China.

Simulation and analysis of river runoff in typical cold regions

It is generally agreed that global warming is taking place, which has caused runoff generation processes and apparently total runoff amount changes in cold regions of Northwestern China. It is absolutely necessary to quantify and analyze earth surface hydrolog- ical processes by numerical models for formulating scientific sustainable development of water resources. Hydrological models became established tools for studying the hydrological cycle, but did not consider frozen soil or glacier hydrology. Thus, they should be improved to satisfy the simulation of hydrological processes in cold regions. In this paper, an energy balance glacier melt model was successfully coupled to the VIC model with frozen soil scheme, thus improving the models performance in a cold catchment area. We performed the improved VIC model to simulate the hydrological processes in the Aksu River Basin, and the simulated results are in good agreement with observed data. Based on modeling hydrological data, the runoff components and their response to climate change were analyzed. The results show： （1） Glacial meltwater recharge accounts fbr 29.2% of runoff for the Toxkan River, and 58.7% for the Kunma Like River. （2） The annual total runoffoftwo branches of the Aksu River show in- creasing trends, increased by about 43.1%, 25.75 X 106 m3 per year for the Toxkan River and by 13.1%, 14.09 ~ l06 m3 per year for the Kunma Like River during the latter 38 years. （3） The annual total runoff of the Toxkan River increased simply due to the increase of non-glacial runoff, while the increase of annual total runoff of the Kunma Like River was the result of increasing gla- cial （42%） and non-glacial runoff （58%）.

2000—2020年阿克苏河流域土地利用时空变化图谱分析

基于2000—2020年阿克苏河流域Landsat遥感影像以及DEM数据,运用图谱理论探究其土地利用时空演变特征及规律。结果表明:(1)2000—2020年阿克苏河流域耕地呈扩张趋势,扩张面积为2951.58 km^(2),主要从草地、未利用地流入,在原有耕地内部及四周扩张,2015年后面积基本保持稳定;(2)建设用地呈现扩张趋势,扩张面积为206.84 km^(2),主要从耕地流入,在原有建设用地的基础上向四周扩张,2015年后面积基本保持稳定;(3)水域呈萎缩趋势,萎缩面积为1653.89 km^(2),主要流出为未利用地和草地,在温宿县冰川积雪处萎缩幅度最大,2015年后有所增长。总体来看,研究区由耕地开垦、建设用地增长的发展模式开始向兼顾生态文明建设的可持续发展方向转型,各主要地类的变化也由急剧发展转向基本可控。

阿克苏河流域地名文化景观分布特征及成因探析

以阿克苏河流域作为内陆河典型样例,探究新疆多民族语言命名的地名文化景观分布特征及成因,促进地名文化传承和保护.基于区域文化和特色将阿克苏河流域地名文化景观划分为自然景观类、文化景观类、农垦类、方位类、其他类,通过核密度和标准差椭圆分析各类别地名的分布特征,并选取特色鲜明的3类地名,分析其与自然地理要素的关系和基因图谱.研究发现:农垦类地名占比最高,整体分散局部集中,具有明显的方向性;自然景观类地名占比其次,受地形、水文因素影响明显;文化景观类地名在绿洲中部较密集,整体呈西北—东南向分布;其他各类别地名受不同因素影响呈不同分布特征,其中“吐木”型地名地貌形态指向性明显,渠系型地名随距渠系距离的增加而减少,对应型地名多分布于水系周边,在河流上游沿河分布明显,河流中游沿渠分布明显.地名文化景观分布特征和成因的分析可为地名非物质文化遗产研究提供一些参考,同时,对区域文化脉络、历史沿革和乡村文化的保护与建设具有现实意义.

阿克苏河流域生态网络构建

阿克苏河流域位于西北干旱区,具有十分典型的绿洲-荒漠格局。构建流域生态网络,对于筑建“一带一路”沿线地区生态屏障具有重要意义。以阿克苏河流域5县市为对象,基于生态源地和阻力面提取流域生态廊道,对比分析1980—2020年流域生态网络变化,根据生态“夹点”和障碍点优化2020年流域生态网络。研究发现:(1)研究期间流域生态源地面积上升6%,空间上存在一定程度的破碎化问题。(2)流域阻力值总体上小幅度上升,在经济较为发达的地区出现以城镇为中心的高阻力值区。(3)研究期间增加6条新的生态廊道,生态网络相较之前更加密集。(4)2020年流域生态网络包含12处夹点和7处障碍点,针对土地覆被类型提出相应的改进措施。研究可为干旱区生态网络修复、关键区域识别和区域绿色发展提供启示。

东昆仑昆中缝合带的活化:来自石炭纪花岗岩的证据

在东昆仑西段工作程度较低的阿克苏河地区,首次识别出石炭纪侵入岩浆活动。阿克苏复式岩体位于昆中断裂带西段,锆石LA-ICP-MS定年显示,花岗闪长斑岩结晶年龄为361±2.4 Ma,二长花岗岩结晶年龄为357.5±2.8 Ma,花岗闪长岩结晶年龄为354±4.3 Ma,代表这些岩体侵位于晚泥盆世—早石炭世(临近昆中缝合带西部),该阶段岩浆事件此前未见公开报道。主量元素分析显示,此套花岗闪长斑岩、二长花岗岩和花岗闪长岩具有富Si、Al、K的特征,为高钾钙碱性过铝质系列;微量和稀土元素分析显示,岩石具有轻、重稀土元素分馏和轻稀土元素富集及负Eu异常特征,富集大离子亲石元素(LILE)Th、U、Rb、K;亏损高场强元素(HFSE)Nb、P、Ti等。锶同位素分析显示,^(87)Sr/^(86)Sr初始值为0.70612~0.71009,εNd(t)为-7.1~-5.1,T DM2为1.51~1.69 Ga。综合岩石-矿物特征和地球化学分析,这些岩石应该属于I型花岗岩,主要为受幔源岩浆作用后地壳物质重熔的结果,指示东昆仑昆中缝合带在石炭纪处于拉张裂解的状态。结合区域岩相学和岩石学资料,推断这一裂解事件应该为古特提斯洋俯冲引起的弧后盆地初始扩张,并将前人认为的古特提斯洋俯冲开启时间为二叠纪提前到石炭纪。

阿克苏河流域高砷地下水分布特征及成因分析

地下水砷污染是十分严重的环境与安全健康问题,研究高砷地下水的分布特征及形成机制能够为高砷地区地下水资源的合理开发利用及当地居民用水安全提供科学依据。以新疆阿克苏河流域为研究区,基于195个地下水水样的实测数据,结合地统计法、Piper三线图、Gibbs图、相关性分析等方法对研究区高砷地下水分布特征及成因进行分析。结果表明:地下水砷含量0.05~210μg/L,均值8.66μg/L,各县市15.09%~27.27%为砷含量大于等于10μg/L的高砷地下水;研究区地下水砷含量整体表现为承压水>潜水,中下游>上游,且高砷地下水主要分布在研究区东南部的阿克苏河流域中下游;研究区具备原生高砷地下水形成的地质条件,主要受自然因素的控制;高砷地下水水化学类型主要为SO_(4)·Cl-Na、SO_(4)·HCO_(3)-Na型;碱性环境下砷的解吸附及脱硫酸作用和岩石风化作用产生的阴离子与吸附态砷的竞争吸附造成地下水砷含量的升高,加之研究区中下游缓慢的水动力条件和强烈的蒸发浓缩作用,使得地下水中的砷进一步富集。研究结果对研究区地下水资源可持续开发利用和生态环境保护具有现实意义。

1956—2006年阿克苏河径流变化及其对区域水资源安全的可能影响

应用新疆塔里木河流域天山南坡阿克苏河流域1956-2006年的实测径流资料,分析了阿克苏河流域各支流径流变化的特征与趋势.结果表明,近50 a来,阿克苏河流域径流量呈显著的增加趋势,其中冰川融水是其主要贡献量.径流量在1994年发生了增多的跃变,原因可能是气温持续升高引起冰川消融径流急剧增多,导致以冰川融水补给为主的河流径流量大增.这种趋势能够持续多久,取决于未来的气候变化及流域上游冰川系统的响应.随着冰川的加剧退缩和较小冰川的消失,短期内会给阿克苏河流域带来丰富的水资源;但是随着冰川补给峰值过后径流量逐渐减小,将会给塔里木河流域带来严重的水资源和生态安全问题.冰川的强烈退缩,还会带来一系列的洪水灾害问题.

1957-2006年天山萨雷扎兹-库玛拉克河流域冰川物质平衡变化及其对河流水资源的影响

天山南坡的萨雷扎兹-库玛拉克河流域在中国阿克苏河协合拉水文站以上面积为12816km2,发育有冰川3195.41km2,冰川覆盖率25%.根据1957—2006年流域站点观测的降水、气温及其径流资料,通过最大熵方法计算了流域冰川物质平衡的逐年变化.结果表明:流域冰川径流深约为895mm,全流域河川径流深为381.3mm,冰川融水占协合拉站控制流量的58.65%,冰川融水变化对流域水资源量的影响非常明显.1957—2006年平均年径流量为48.64×108m3,径流在1993年后急剧增加,1994—2006年的平均年径流量比1957—1993年的增加了10.56×108m3,即增加了23%.由于负物质平衡消耗了大量过去积累的冰川冰,冰川融化对河流额外补给.初步计算,在过去50a由于气温升高引起的冰川净消融额外补给河流的径流量达309.47×108m3,相当于每年径流增加达6.19×108m3,约为年径流量的13%.1957—1993年流域冰川消融对河流的额外净补给量为5.3×108m3,占河流总径流量的11%;1994—2006年流域冰川消融对河流的额外净补给量为8.8×108m3,占河流总径流量的18%.随着气候变暖,虽然降水量增加,但冰川对气温的敏感性更大,冰川消融量加快,冰川融水量持续增加.到21世纪末,随着气温上升和降水增加,年均径流相对1991—2006年将增加11.75×108m3,增幅为22%.

1396-2005年天山南坡阿克苏河流域降水序列重建与分析

利用2005年采自天山南坡阿克苏河流域的树轮样本,建立了该流域6个树轮年表.相关计算表明,天山南坡阿克苏河流域英阿特河树轮标准化年表与该区域上年8月到当年4月的降水相关最为显著.利用该年表较好地重建了阿克苏气象站1396—2005年上年8月到当年4月的降水序列,经多方面验证表明其具有较好的可信性.分析表明:在过去600 a中,天山南坡阿克苏河流域降水以2~2.5a、12~13 a、45 a、50 a、58 a的周期最为显著;在1584年,1615年,1685年,1722年和1753年前后曾发生了突变,15、19、20世纪天山南坡阿克苏河流域的降水相对稳定.在1416—1990年经历了9个偏湿期及9个偏干期,阿克苏河流域过去600 a来降水有增加的趋势;降水年际变化极不均匀,洪水、干旱、雪灾等自然灾害频繁发生.