Monitoring Glacier and Supra-glacier Lakes from Space in Mt. Qomolangma Region of the Himalayas on the Tibetan Plateau in China

Because of the large number and remoteness, satellite data, including microwave data and optical imagery, have commonly been used in alpine glaciers surveys. Using remote sensing and Geographical Information System （GIS） techniques, the paper presents the results of a multitemporal satellite glacier extent mapping and glacier changes by glacier sizes in the Mt. Qomolangma region at the northern slopes of the middle Himalayas over the Tibetan Plateau. Glaciers in this region have both retreated and advanced in the past 35 years, with retreat dominating. The glacier retreat area was 3.23 km2 （or o.75 km^2 yr^-1 during 1974 and 1976, 8.68 km^2 （or 0.36 km^2 yr^-1 during 1976 and 1992, 1.44 km^2 （or 0.12 km^2 yr^-1） during 1992-2ooo. 1.14 km^2 （or 0.22 km^2 yr^-1 during 2000-2003, and 0.52 km^2 （or 0.07 km^2 yr^-1 during 2003-2008, respectively. While supra-glacier lakes on the debris-terminus of the Rongbuk Glacier were enlarged dramatically at the same time, from 0.05 km^2 in 1974 increased to 0.71 km^2 in 2008, which was more than 13 times larger in the last 35 years. In addition, glacier changes also showed spatial differences, for example, glacier retreat rate was the fastest at glacier termini between 5400 and 5700 m a.s.l than at other elevations. The result also shows that glaciers in the middle Himalayas retreat almost at a same pace with those in the western Himalayas.

Unveiling evapotranspiration patterns and energy balance in a subalpine forest of the Qinghai-Tibet Plateau:observations and analysis from an eddy covariance system

Evapotranspiration is an important parameter used to characterize the water cycle of ecosystems.To under-stand the properties of the evapotranspiration and energy balance of a subalpine forest in the southeastern Qinghai-Tibet Plateau,an open-path eddy covariance system was set up to monitor the forest from November 2020 to October 2021 in a core area of the Three Parallel Rivers in the Qing-hai-Tibet Plateau.The results show that the evapotranspira-tion peaked daily,the maximum occurring between 11:00 and 15:00.Environmental factors had significant effects on evapotranspiration,among them,net radiation the greatest(R^(2)=0.487),and relative humidity the least(R^(2)=0.001).The energy flux varied considerably in different seasons and sensible heat flux accounted for the main part of turbulent energy.The energy balance ratio in the dormant season was less than that in the growing season,and there is an energy imbalance at the site on an annual time scale.

Dataset of Comparative Observations for Land Surface Processes over the Semi-Arid Alpine Grassland against Alpine Lakes in the Source Region of the Yellow River

Thousands of lakes on the Tibetan Plateau(TP) play a critical role in the regional water cycle, weather, and climate. In recent years, the areas of TP lakes underwent drastic changes and have become a research hotspot. However, the characteristics of the lake-atmosphere interaction over the high-altitude lakes are still unclear, which inhibits model development and the accurate simulation of lake climate effects. The source region of the Yellow River(SRYR) has the largest outflow lake and freshwater lake on the TP and is one of the most densely distributed lakes on the TP. Since 2011,three observation sites have been set up in the Ngoring Lake basin in the SRYR to monitor the lake-atmosphere interaction and the differences among water-heat exchanges over the land and lake surfaces. This study presents an eight-year(2012–19), half-hourly, observation-based dataset related to lake–atmosphere interactions composed of three sites. The three sites represent the lake surface, the lakeside, and the land. The observations contain the basic meteorological elements,surface radiation, eddy covariance system, soil temperature, and moisture(for land). Information related to the sites and instruments, the continuity and completeness of data, and the differences among the observational results at different sites are described in this study. These data have been used in the previous study to reveal a few energy and water exchange characteristics of TP lakes and to validate and improve the lake and land surface model. The dataset is available at National Cryosphere Desert Data Center and Science Data Bank.

Tectonics and Topography of the Tibetan Plateau in Early Miocene

Early Miocene stratigraphy,major structural systems,magmatic emplacement,volcanic eruption,vegetation change and paleo-elevation were analyzed for the Tibetan Plateau after regional geological mapping at a scale of 1：250,000 and related researches,revealing much more information for tectonic evolution and topographic change of the high plateau caused by Indian-Asian continental collision.Lacustrine deposits of dolostone,dolomite limestone,limestone,marl,sandstone and conglomerate of weak deformation formed extensively in the central Tibetan Plateau,indicating that vast lake complexes as large as 100,000-120,000 km2 existed in the central plateau during Early Miocene.Sporopoilen assemblages contained in the lacustrine strata indicate the disappearance of most tropical-subtropical broad-leaved trees since Early Miocene and the flourishing of dark needle-leaved trees during Early Miocene.Such vegetation changes adjusted for latitude and global climate variations demonstrate that the central Tibetan Plateau rose to ca.4,000-4,500 m and the northeastern plateau uplifted to ca.3,500-4,000 m before the Early Miocene.Intensive thrust and crustal thickening occurred in the areas surrounding central Tibetan Plateau in Early Miocene,formed Gangdise Thrust System （GTS） in the southern Lhasa block,Zedong-Renbu Thrust （ZRT） in the northern Himalaya block,Main Central Thrust （MCT） and Main Boundary Thrust （MBT） in the southern Himalaya block,and regional thrust systems in the Qaidam,Qilian,West Kunlun and Songpan-Ganzi blocks.Foreland basins formed in Early Miocene along major thrust systems,e.g.the Siwalik basin along MCT,Yalung-Zangbu Basin along GTS and ZRT,southwestern Tarim depression along West Kunlun Thrust,and large foreland basins along major thrust systems in the northeastern margin of the plateau.Intensive volcanic eruptions formed in the Qiangtang,Hoh-Xil and Kunlun blocks,porphyry granites and volcanic eruptions formed in the Nainqentanglha and Gangdise Mts.,and leucogranites and granites formed in the Himalaya and Longmenshan Mts.in Early Miocene.The K2O weight percentages of Early Miocene magmatic rocks in the Gangdise and Himlayan Mts.are found to increase with distance from the MBT,indicating the genetic relationship between regional magmatism and subduction of Indian continental plate in Early Miocene.

An integrated north–south paleo-Dadu-Anning River: New insights from bulk major and trace element analyses of the Xigeda Formation

The Xianshuihe-Anninghe fault extends SE–S and constitutes the southeastern margin of the Tibetan Plateau.However,the Dadu River which is associated with the fault does not flow following the path,but makes a 90ºturn within a distance of 1 km at Shimian,heading east,and joins the Yangtze River,finally flowing into the East China Sea.Adjacent to the abrupt turn,a low and wide pass near the Daqiao reservoir at Mianning separates the N–S course of the Dadu River from the headwater of the Anning River which then flows south into the Yunnan Province along the Anninghe fault.Therefore,many previous studies assumed southward flow of the paleo-Dadu River from the Shimian to the Anning River.However,evidences for the capture of the integrated N–S paleo-Dadu-Anning River,its timing,and causes are still insufficient.This study explored the paleo-drainage pattern of the Dadu and Anning Rivers based on bulk mineral and geochemical analyses of the large quantities of fluvial/lacustrine sediments along the trunk of the Dadu and Anning Rivers.Similar with sands in the modern Dadu River,the Xigeda sediments also exhibit a granitoid affinity with the bulk major mineral compositions of quartz(>50%),anorthite(about 10%),orthoclase(about 5%),muscovite(about 5%),and clinochlore(about 4%).Correspondingly,bulk major elements show high SiO_(2),with all samples>60%,and some of them>70%,low TiO_(2)(≤0.75%),P_(2)O_(5)(≤0.55%),FeO*(≤5%),and relatively high CaO(1.02%–8.51%),Na_(2)O(1.60%–2.52%),and K_(2)O(2.17%–2.71%),with a uniform REE patterns.Therefore,synthesizing all these results indicate that these lacustrine sediments have similar material sources,which are mainly derived from its course in the Songpan-Ganzi flysch block,implying that the paleo-Dadu originally flowed southward into the Anning River and provided materials to the Xigeda ancient lake.The rearrangement of the paleo-Dadu River appears to be closely related to the locally focused uplift driven by strong activities of the XianshuiheXiaojiang fault system.

Unraveling the mechanisms underlying lake expansion from 2001 to 2020 and its impact on the ecological environment in a typical alpine basin on the Tibetan Plateau

Yanhu Lake basin(YHB)is a typical alpine lake on the northeastern Tibetan Plateau(TP).Its continuous expansion in recent years poses serious threats to downstream major projects.As a result,studies of the mechanisms underlying lake expansion are urgently needed.The elasticity method within the Budyko framework was used to calculate the water balance in the Yanhu Lake basin(YHB)and the neighboring Tuotuo River basin(TRB).Results show intensification of hydrological cycles and positive trends in the lake area,river runoff,precipitation,and potential evapotranspiration.Lake expansion was significant between 2001 and 2020 and accelerated between 2015 and 2020.Precipitation increase was the key factor underlying the hydrological changes,followed by glacier meltwater and groundwater.The overflow of Yanhu Lake was inevitable because it was connected to three other lakes and the water balance of all four lakes was positive.The high salinity lake water diverted downstream will greatly impact the water quality of the source area of the Yangtze River and the stability of the permafrost base of the traffic corridor.

Extracting water body data based on SDWI and threshold segmentation:A case study in permafrost area surrounding Salt Lake in Hoh Xil,Qinghai-Tibet Plateau,China

There are a large number of lakes,rivers,and other natural water bodies distributed in the permafrost area of the Qinghai-Tibet Plateau(QTP).The changes in water bodies will affect the distribution of water resources in sur-rounding areas and downstream areas,resulting in environmental impact and bringing potential flood disasters,which will induce more serious issues and problems in alpine and high-altitude areas with a fragile habitat(such as the QTP in China).Generally,effective,reasonable,and scientific monitoring of large-scale water bodies can not only document the changes in water bodies intuitively,but also provide important theoretical reference for subsequent environmental impact prediction,and disaster prevention and mitigation in due course of time.The large-scale water extraction technology derived from the optical remote sensing(RS)image is seriously affected by clouds,bringing about large differences among the extracted water result products.Synthetic aperture radar(SAR)RS technology has the unique advantage characteristics of all-weather,all-day,strong penetration,and not being affected by clouds,which is hopeful in extracting water body data,especially for days with cloudy weather.The data extraction of large-scale water bodies based on SAR images can effectively avoid the errors caused by clouds that become prevalent at present.In this paper,the Hoh Xil Salt Lake on the QTP and its surrounding five lakes are taken as the research objects.The 2-scene Sentinel-1 SAR image data covering the whole area on 22 August 2022 was used to verify the feasibility of extracting water body data in permafrost zones.Furthermore,on 22 August 2022,the wealth here was cloudy,which made the optical RS images,e.g.,Sentinel-2 images full of clouds.The results show that:using the Sentinel-1 image and threshold segmentation method to extract water body data is efficient and effective with excellent results in permafrost areas.Concretely,the Sentinel-1 dual-polarized water index(SDWI),calculated by combining dual vertical–vertical(VV)polarized and verti-cal–horizontal(VH)polarized data is a useful index for water extraction and the result is better than each of the VV or VH polarized images.

THE DISCOVERED DEEP BURIED LAKE ICE IN SOURCE REGION OF THE HUANGHE RIVER

The 4.45 m-thick pure ice lens have been discovered firstly at depth from 19.81 -24.26 m in the bore No.6, which locates in north bank of the Ngoring Lake. In source region of the Huanghe (Yellow) River, 14C dating, X -ray diffraction, pollen analysis, micropalaeontology, chemical components, environmental isotope 2H, 3H, 18O and freezing point of the ice and water samples from the bore have been tested and microorganism in the ice have been also appraised with microscope. Combined with the research on geomorphy and Quaternary around the lake, the ice lens are determined as a kind of deep-buried lake ice, formed in 35,030-45,209 yr.B.P., and annual mean air temperature was about -10℃ during that time.

Water Environmental Degradation of the Source Area of the Yellow River on Northeast Qinghai-Tibet Plateau

The issue on water environmental degradation in the source area of the Yellow River has been one of very serious ecological and socially economic problems. The temporal-spatial changes of water environment led to the decreasing of land capacity and river disconnecting. The status of water environmental degradation in this paper was analyzed based on the data and field investigation. The results indicated that the surface water area in the region has obviously decreased owing to the climate changes and human irrational use of water resources and the continuous lowering of the regional groundwater table and the steadily decreasing tendency of the flow rate in the source areas of the Yellow River.

青藏高原不同水体氢氧稳定同位素特征

为揭示青藏高原区域水文循环机制和促进水资源合理利用,基于氢氧稳定同位素技术分析不同水体氢氧稳定同位素特征和转化关系,应用端元混合径流分割模型和IsoSource软件进行流域水源解析。结果表明:区域大气降水δ(^(18)O)值2—5月上升、5—10月下降;氘盈余值冬季高夏季低;δ(^(18)O)在青藏高原北部地区表现出“逆海拔效应”,区域内其他地区“海拔效应”明显。河水、湖水、地下水的平均蒸发损失量分别为20.8%、30.9%、23.6%。河水氢氧稳定同位素的沿程变化受补给水源和蒸发作用影响,降水补给使得河水δ(^(18)O)减小,重同位素相对富集的地下水补给导致河水δ(^(18)O)增大,蒸发作用使得河水δ(^(18)O)增大,蒸发效应使得湖水重同位素富集,湖水注入河道后导致河水δ(^(18)O)增大。降水是拉萨河流域的最主要补给水源,而对于疏勒河流域的补给水源来说,降水和地下水平均贡献率相近,岷江流域则以地下水补给居多。那曲河流域下游受错那湖调节,随着沿程距离的增加,湖水补给贡献率呈下降趋势。

Distribution and transportation of mercury from glacier to lake in the Qiangyong Glacier Basin, southern Tibetan Plateau, China

The Tibetan Plateau is home to the largest aggregate of glaciers outside the Polar Regions and is a source of fresh water to 1.4 billion people. Yet little is known about the transportation and cycling of Hg in high-elevation glacier basins on Tibetan Plateau. In this study, surface snow,glacier melting stream water and lake water samples were collected from the Qiangyong Glacier Basin. The spatiotemporal distribution and transportation of Hg from glacier to lake were investigated. Significant diurnal variations of dissolved Hg（DHg） concentrations were observed in the river water, with low concentrations in the morning（8：00 am–14：00 pm） and high concentrations in the afternoon（16：00 pm–20：00 pm）. The DHg concentrations were exponentially correlated with runoff, which indicated that runoff was the dominant factor affecting DHg concentrations in the river water. Moreover, significant decreases of Hg were observed during transportation from glacier to lake. DHg adsorption onto particulates followed by the sedimentation of particulate-bound Hg（PHg） could be possible as an important Hg removal mechanism during the transportation process. Significant decreases in Hg concentrations were observed downstream of Xiao Qiangyong Lake, which indicated that the high-elevation lake system could significantly affect the distribution and transportation of Hg in the Qiangyong Glacier Basin.

藏北环纳木错湖区岩画遗存的时代分析

文章是2021年“环纳木错湖泊区科学考察队”对西藏纳木错及藏北高海拔湖区岩画考古调查的年代学研究报告。文章对纳木错扎西岛、尼玛县加林山和夏桑三处具有代表性的岩画遗存进行了包括U-Th与C14测年技术在内的考古学综合分析,认为纳木错等藏北内陆湖泊地区两种技术(琢刻、涂绘)制作的岩画其时代是基本平行共存的,该区域大量岩画制作于距今2000年前后至7~9世纪的吐蕃时期,U-Th与C14测年数据还显示其中涂绘岩画的制作可能早到距今2200年或更早。对岩画遗存形式的分析表明,纳木错扎西岛至少在公元7~9世纪,已是藏北神祇崇拜及宗教信仰的重要场所,而不同文化因素的岩画显示出古代西藏积极参与“高原丝绸之路”的文化互动,即古代西藏与不同民族和地区文化的交往交流与交融。

Characteristics and influencing factors of CO_(2) emission from inland waters in China

Inland water bodies,being the most active biogeochemical cycle reactors,play a pivotal role in the global carbon cycle and CO_(2) budget.This study integrates existing observation dataset of CO_(2) flux(fCO_(2))in rivers,lakes and reservoirs in China,to elucidate their spatial-temporal patterns and key influencing factors and to reappraise the significance for regional carbon balance.It showed that,the fCO_(2) in rivers,lakes and reservoirs in China presented significant variability with large range of-379.3-4947.6,-160.1-785.0 and -74.0-1603.1 mg CO_(2)m-2h^(-1),respectively.The median of the fCO_(2) in rivers was of 228.5 mg CO_(2)m^(-2)h^(-1),observably higher than these in lakes and reservoirs(26.0 and 28.3 mg CO_(2)m^(-2)h^(-1),respectively).The fCO_(2)in rivers and reservoirs exhibited similar decreasing trend from south to north as a result of universal climate restraint,the averaged fCO_(2) in Pearl River and Yangtze River basins showed much higher than that in Northeastern rivers.While,the averaged fCO_(2) in the Mongolia-Xinjiang lake district and the Northeast lake district were higher than other lake districts,followed by the Qinghai-Xizang lake district,and the Eastern and Yungui lake district were generally low,contradicting the climatic restriction.The water primary production enhancement resulting from human activities was the main driver of spatial variation in the fCO_(2) in lakes.Meanwhile,the fCO_(2) in rivers presented seasonal pattern with higher wet season than dry season,while opposite patterns were found in lakes and reservoirs.Seasonal temperature,precipitation and water primary production were main factors.Furthermore,it showed pH was a key factor indicating the variability of the fCO_(2) levels either in rivers,lakes or in reservoirs.In lakes,the fCO_(2) is closely linked to chlorophyll a(Chl-a)and dissolved oxygen(DO),whereas,the fCO_(2) in rivers is primarily associated with organic carbon(OC)and total nitrogen(TN),highlighting the diverse controlling mechanisms of fCO_(2) in various inland water types.In addition,we found that water body sizes play an important role in regulating the fCO_(2) levels,and small waters act as hotspots ofCO_(2) flux.Additionally,widespread urbanization and agricultural activities may enhance CO_(2) emissions from rivers but potentially mitigating that from lakes.Nevertheless,the comprehensive impact of these factors on CO_(2) emissions in inland water requires further evaluation.Based on the extrapolation method,we re-estimated that the total CO_(2) emission of inland waters in China is approximately 117.3 Tg yr^(-1),which could offset 4.6%-12.8% of the total land carbon sink in China.

无人机河湖巡检中BPT结点区域合并算法应用研究

针对无人机河湖巡检图像存在较高的域内异质性、域间同质性,使用单阶段的分割算法易形成不完整目标区域提取结果等问题,设计一种基于二叉划分树结点的区域合并算法。算法包含初始分割、区域合并2个阶段,采用分水岭算法进行初始分割形成误分割率较低的过分割区域集,对过分割区域集合中的区域对进行相似性度量,根据过相似性度量结果构建BPT树,遍历BPT树确定过分割区域集合的合并次序。在河湖巡检数据集上,与自适应区域合并进行对比,结果表明:基于二叉划分树结点的区域合并算法的分割精度、时间效率均优于自适应区域合并算法,可以实现目标在图像中的精确提取。

洮滆地区河湖生态治理路径探索

从洮滆地区水环境、水生态和河湖引排等方面的现状分析,从高标准建成太湖上游生态屏障的要求,针对性地提出河湖生态治理路径,通过控源截污、水系连通、生态修复、综合管理,全力复苏河湖生态,改善环境质量,形成太湖流域上游生态保护屏障,探索形成可复制、可推广的流域河湖生态治理的可持续发展模式。

河湖连通工程对区域水资源分配的影响分析

深入探讨了河湖连通工程对区域水资源分配的影响,通过调节水资源在空间上的不均匀分布,增强地区间水资源的应急互补能力,从而提升区域水资源利用效率,促进经济社会可持续发展。通过全面评估河湖连通工程的效果和潜在风险,提出了优化水资源管理和减少生态环境风险的策略。科学的河湖连通工程能显著提高水资源分配效率,但同时需要有效的监管措施以确保工程的长期效益和生态安全。

三江源多年冻土活动层厚度变化特征研究

作为多年冻土与外界大气间水热交换的主要场所,活动层及其变化特征显著影响着地―气间水热交换、碳循环、地表及地下水文过程、地形地貌、生态系统和寒区工程建筑物安全。本文利用三江源区内多年冻土活动层厚度的实测数据,基于修正Stefan模型对三江源区多年冻土活动层厚度的空间分布特征及其未来变化趋势进行了研究,并对可能影响活动层厚度变化的因素进行了讨论。结果表明,1981—2018年,活动层厚度增大的速率达7.2 cm·(10a)^(-1)。未来活动层厚度仍呈现增大的趋势,增大最明显的是三江源中部地区。2006—2049年,活动层厚度以4.3 cm·(10a)^(-1)(RCP6.0)到6.8 cm·(10a)^(-1)(RCP8.5)速率增大;2050—2099年,以0.04 cm·(10a)^(-1)(RCP2.6)到5.6 cm·(10a)^(-1)(RCP8.5)速率增大,明显小于前50年的增大速率,活动层厚度增大速率变缓。对活动层厚度变化影响因素分析表明,影响最大的是年平均气温,年降水量的影响并不明显,而NDVI对活动层厚度有一定的影响。本文的结果将会对三江源区的水源涵养、气候调节和生态安全等方面产生重要影响。

长江源区湖泊-冰川变化特征及其对气候变化的响应

湖泊是气候变化的敏感指示器,研究其动态变化对揭示全球气候变化及水资源利用与管理具有重要意义。本文以长江源区多尔索洞错-米提江占木错为研究对象,应用Landsat-5/7/8卫星和高分遥感影像,分析了1989—2021年湖泊面积变化的时空特征,并探讨了冰湖-冰川对气候变化的响应。结果表明,1989—2021年间,多尔索洞错-米提江占木错湖泊平均面积为1011.37 km^(2),由1989年的872.07km^(2)扩张至2021年的1119.5 km^(2),平均扩张率为8.62 km^(2)·a^(-1)。从年代际变化来看,21世纪初期湖泊面积扩张最明显,尤其是在湖泊北部、西北部及南部地区;20世纪90年代增长最为缓慢。1990—2020年各拉丹冬冰川面积从1990年的797.85 km^(2)缩小至2020年的766.19 km^(2),减少了31.66 km^(2),缩减率为1.106 km^(2)·a^(-1)。2004年之前,气温升高引起的冰川融水是多尔索洞错-米提江占木错湖泊面积变化的主要因素,对湖泊面积变化的平均贡献率为66.8%;2004年之后,降水在多尔索洞错-米提江占木错湖泊面积变化因素中起主导作用,降水对湖泊面积变化的平均贡献率为57.8%。

长沙—岳阳空间协同发展规划策略研究

长岳协同发展是湖南实施强省会战略、发挥省会长沙核心辐射功能的必然要求。基于长江经济带发展战略、“一带一路”倡议、湖南强省会战略、长株潭都市圈战略以及长沙与岳阳两市发展战略等,考量长沙城市发展战略空间向洞庭湖区延伸的重要战略意义;分析长沙与岳阳空间协同化发展的优势与不足;从战略定位、空间布局、交通体系、产业发展、环境保护和机制创新等6个方面出发,提出长岳空间协同发展的规划策略。

盐湖漫溢对多年冻土区桥梁墩台影响对策研究

近年来,青藏高原多年冻土区盐湖面积不断扩大,漫溢后形成高矿化度水流流经铁路、公路的桥梁墩台,给线路运营造成了较大的安全隐患。针对盐湖漫溢河道处的桥梁工程进行研究,分析了盐湖漫溢对桥梁墩台带来的主要影响,提出了针对性的防治对策,并基于现场监测数据对工程效果进行了评价。主要结论包括:高矿化度水流对桥梁墩台造成的影响主要有河道下切严重,对地基多年冻土热干扰严重和对桥墩及基础混凝土腐蚀。针对高矿化度水流对桥梁墩台的影响,提出了区域河流疏导和冻土防护、桥墩基础冻土热防护、桥梁结构构造防腐蚀3个方面的整治技术;根据初期监测数据分析,高矿化度水流流量较大,造成下部冻土退化严重,但在合理的整治工程实施后,近1年多来未发现桥梁墩台变形。同时,地温监测数据验证了热棒具有保持多年冻土稳定的作用。