Land surface evapotranspiration(ET)is a critical component in the hydrological cycle but has not well been understood in data-scarce areas especially in river basins,like Nujiang River(NRB)which is characterized by la...Land surface evapotranspiration(ET)is a critical component in the hydrological cycle but has not well been understood in data-scarce areas especially in river basins,like Nujiang River(NRB)which is characterized by large elevation gradient and different vegetation zones with complex processes of water and energy exchange.The quality of ET from optical remote sensing is constrained by cloud cover which is common in the NRB in the monsoon seasons.To understand factors controlling the spatial-temporal heterogeneity of ET in NRB,we employed the Variable Infiltration Capacity(VIC)hydrological model by parameter optimization with support of quality controlled remote sensing ET product and observed river runoff series in the river.The modeled ET has increased during 1984-2018,which might be one of the reasons for the runoff decrease but precipitation increase in the same period.ET increase and runoff decrease tended to be quicker within altitudinal band of 2000-4000 m than in other areas in NRB.We observed that ET variation in different climatic zones were controlled by different factors.ET is generally positively correlated with precipitation,temperature,and shortwave radiation but negatively with relative humidity.In the Tundra Climate(Et)zone in the upper reach of NRB,ET is controlled by precipitation,while it is controlled by shortwave radiation in the snow climate with dry winter(Dw)zone.ET increase is influenced by the increase of temperature,wind speed,and shortwave radiation in the middle and downstream of NRB with warm temperate climate,fully humid(Cf)and warm temperate climate with dry winter(Cw).展开更多
Within the context of the Belt and Road Initiative(BRI)and the China-Myanmar Economic Corridor(CMEC),the Dulong-Ir-rawaddy(Ayeyarwady)River,an international river among China,India and Myanmar,plays a significant role...Within the context of the Belt and Road Initiative(BRI)and the China-Myanmar Economic Corridor(CMEC),the Dulong-Ir-rawaddy(Ayeyarwady)River,an international river among China,India and Myanmar,plays a significant role as both a valuable hydro-power resource and an essential ecological passageway.However,the water resources and security exhibit a high degree of vulnerabil-ity to climate change impacts.This research evaluates climate impacts on the hydrology of the Dulong-Irrawaddy River Basin(DIRB)by using a physical-based hydrologic model.We crafted future climate scenarios using the three latest global climate models(GCMs)from Coupled Model Intercomparison Project 6(CMIP6)under two shared socioeconomic pathways(SSP2-4.5 and SSP5-8.5)for the near(2025-2049),mid(2050-2074),and far future(2075-2099).The regional model using MIKE SHE based on historical hydrologic processes was developed to further project future streamflow,demonstrating reliable performance in streamflow simulations with a val-idation Nash-Sutcliffe Efficiency(NSE)of 0.72.Results showed that climate change projections showed increases in the annual precip-itation and potential evapotranspiration(PET),with precipitation increasing by 11.3%and 26.1%,and PET increasing by 3.2%and 4.9%,respectively,by the end of the century under SSP2-4.5 and SSP5-8.5.These changes are projected to result in increased annual streamflow at all stations,notably at the basin’s outlet(Pyay station)compared to the baseline period(with an increase of 16.1%and 37.0%at the end of the 21st century under SSP2-4.5 and SSP5-8.5,respectively).Seasonal analysis for Pyay station forecasts an in-crease in dry-season streamflow by 31.3%-48.9%and 22.5%-76.3%under SSP2-4.5 and SSP5-8.5,respectively,and an increase in wet-season streamflow by 5.8%-12.6%and 2.8%-33.3%,respectively.Moreover,the magnitude and frequency of flood events are pre-dicted to escalate,potentially impacting hydropower production and food security significantly.This research outlines the hydrological response to future climate change during the 21st century and offers a scientific basis for the water resource management strategies by decision-makers.展开更多
Satellite-based precipitation products have been widely used to estimate precipitation, especially over regions with sparse rain gauge networks. However, the low spatial resolution of these products has limited their ...Satellite-based precipitation products have been widely used to estimate precipitation, especially over regions with sparse rain gauge networks. However, the low spatial resolution of these products has limited their application in localized regions and watersheds.This study investigated a spatial downscaling approach, Geographically Weighted Regression Kriging(GWRK), to downscale the Tropical Rainfall Measuring Mission(TRMM) 3 B43 Version 7 over the Lancang River Basin(LRB) for 2001–2015. Downscaling was performed based on the relationships between the TRMM precipitation and the Normalized Difference Vegetation Index(NDVI), the Land Surface Temperature(LST), and the Digital Elevation Model(DEM). Geographical ratio analysis(GRA) was used to calibrate the annual downscaled precipitation data, and the monthly fractions derived from the original TRMM data were used to disaggregate annual downscaled and calibrated precipitation to monthly precipitation at 1 km resolution. The final downscaled precipitation datasets were validated against station-based observed precipitation in 2001–2015. Results showed that: 1) The TRMM 3 B43 precipitation was highly accurate with slight overestimation at the basin scale(i.e., CC(correlation coefficient) = 0.91, Bias = 13.3%). Spatially, the accuracies of the upstream and downstream regions were higher than that of the midstream region. 2) The annual downscaled TRMM precipitation data at 1 km spatial resolution obtained by GWRK effectively captured the high spatial variability of precipitation over the LRB. 3) The annual downscaled TRMM precipitation with GRA calibration gave better accuracy compared with the original TRMM dataset. 4) The final downscaled and calibrated precipitation had significantly improved spatial resolution, and agreed well with data from the validated rain gauge stations, i.e., CC = 0.75, RMSE(root mean square error) = 182 mm, MAE(mean absolute error) = 142 mm, and Bias = 0.78%for annual precipitation and CC = 0.95, RMSE = 25 mm, MAE = 16 mm, and Bias = 0.67% for monthly precipitation.展开更多
A 606 year runoff reconstruction of the Kara Darya River was developed, based on the tree-ring width chronology of Turkestan juniper(Juniperus turkestanica) from the Pamir-Alai Mountains of Kyrgyzstan. Preliminary com...A 606 year runoff reconstruction of the Kara Darya River was developed, based on the tree-ring width chronology of Turkestan juniper(Juniperus turkestanica) from the Pamir-Alai Mountains of Kyrgyzstan. Preliminary comparison between the snow cover variation and these climate/runoff reconstructions found that Central Asian snow cover may have strong associations with large-scale ocean-atmosphere-land circulations. The runoff reconstruction demonstrated that instrumental runoff was not representative of runoff over the past 606 years. The drought of the 1960 s-1990 s resulted in low runoff levels during the past 50 years;however, this probably does not represent a worst-case scenario for the Kara Darya because the runoff reconstruction showed additional extremely low runoff prior to the 20 th century. The reconstruction will provide a long-term perspective on runoff variation in the Kara Darya River basin, aid sustainable water resource management and be useful in guiding expectations of future variations and water resource planning.展开更多
Glaciers in the northern Pakistan are a distinctive source of freshwater for the irrigation,drinking and industrial water supplies of the people living in those regions and downstream. These glaciers are under a direc...Glaciers in the northern Pakistan are a distinctive source of freshwater for the irrigation,drinking and industrial water supplies of the people living in those regions and downstream. These glaciers are under a direct global warming impact as indicated in many previous studies. In this study, we estimated the glacier dynamics in terms of Equilibrium Line Altitude(ELA), mass balance and the snout position variation using remote sensing data between 2001 and 2018. Six glaciers, having area≥ 20 km2 each, situated in the Chitral region(Hindukush Mountains) were investigated in this study. Digital Elevation Model(DEM) and available cloud-free continuous series of Landsat and Sentinel satellite images from minimum snow cover season were used to monitor the variability in the studied glaciers by keeping the status of glaciers in year 2001 as a reference. The annual climatic trends of mean temperature and total precipitation from Chitral weather station were detected using the nonparametric Mann-Kendall’s test. Results revealed a general increase in the ELA, decrease in the glacier mass balance and the retreat of snout position.Average upward shift in the ELA for the entire study area and data period was ~345 ± 93 m at a rate of^13 m.a-1 from the reference year’s position i.e.~4803 m asl. Estimated mean mass balance for the entire study area indicated a decline of-0.106 ± 0.295 m w.e. a-1. Periods of snout retreat and advance in different glaciers were found but the mean value over the entire study area was a retreat of-231 ± 140 m.No obvious relationship was found between the glacier variation trends and the available gauged climatic data possibly due to the presence of debris cover in ablation zones of all the studied glaciers which provides insulation and reduces the immediate climatic effects.展开更多
Understanding the evolution of the fluvial geomorphology in an orogenic belt provides valuable insight into the relationship between upper crustal deformation and surface processes.The upper Lancang-Mekong River is in...Understanding the evolution of the fluvial geomorphology in an orogenic belt provides valuable insight into the relationship between upper crustal deformation and surface processes.The upper Lancang-Mekong River is in an area experiencing both uplift and erosion.The related processes provide a steady sediment supply to the lower reaches of the river and play an important role in the regional environmental changes.The Xiaohei(Weiyuan)River Basin is an important sub-basin in this area,which is characterized by large-scale topographic fluctuations,active tectonics and erosion,and anthropogenic activities.These different factors introduce numerous complexities to the local surface processes.In this study,we investigate and quantify the controls of geomorphic evolution of the Xiaohei River Basin.We located and mapped the main knick-zones within the channels and examined the main genetic factors,such as faults and stratigraphic differences.The results show that the areas with the lowest uplift rates are characterized by a low steepness index and are located in the southeastern part of the basin.The stream power of the mainstream increases downstream,with an average value of^122 W/m.The erosional activity of the various stream channels is intense.Overall,the basin tends to expansion,with only local instances of inward contraction.Our analysis confirms that a number of the geomorphic evolutionary characteristics of the Xiaohei River Basin are transient.In addition,the future potential for the increasing the number of dams and the hydropower development in the basin may weaken the expansion trend of the basin over a long period of time.展开更多
The snow cover over the Qinghai-Tibet Plateau(QTP)and its surrounding areas is very sensitive to climate changes.Due to the complexity of geographical environment in this large region,the response of snow cover to cli...The snow cover over the Qinghai-Tibet Plateau(QTP)and its surrounding areas is very sensitive to climate changes.Due to the complexity of geographical environment in this large region,the response of snow cover to climate change should exhibit spatiotemporal differences.In this study,the spatiotemporal variations of snow cover from 2002-2015 in the Yarlung Tsangpo-Brahmaputra River Basin(YBRB)were analyzed using an optimized fractional snow cover(FSC)product derived from Moderate Resolution Imaging Spectroradiometer(MODIS).Additionally,the effects of temperature and precipitation on the variability of snow cover were also investigated.The results showed that:(1)The snow cover exhibited large spatial and temporal heterogeneity in the YBRB.High FSC was observed in the northeast of the basin and the south slope of Himalaya,while the lowest was concentrated in the broad valley of the upstream of YBRB.The FSC value reached its highest in winter and dropped to its lowest in summer,but the monthly change processes were different between upstream and downstream regions.(2)A slightly increasing tendency(3.76%/10 a)of snow cover was observed on basin-wide,but the changes varied through time and space.The FSC increased significantly in the source and midstream regions during winter to spring(10.5%-18.0%/10 a),while it changed slightly in summer over all parts of the basin(-0.4%-4.3%/10 a).(3)The study area generally became warm and wet,and the change trend of temperature was more significant than that of precipitation.Snow cover changes were weakly correlated with temperature in winter and precipitation in summer.But in spring and autumn,both precipitation and temperature were significantly related to snow cover change in most regions of the basin.(4)The dominant factor driving the changes of snow cover varied in seasons.The area dominated by temperature was slightly larger than that dominated by precipitation in spring,except that precipitation significantly dominated the snow cover changes in the source region;In summer and autumn,temperature contributed more to the snow cover change in most areas of the basin;However,in winter,precipitation played a leading role in the variations of snow cover.These findings help to understand the different performance of the snow cover in the QTP and its surrounding areas under future climate change.展开更多
Surface sediment is one of the main sources of nutrients in overlying water environments, and these can also indirectly reflect the degree of eutrophication. In this paper, the spatial distribution characteristics of ...Surface sediment is one of the main sources of nutrients in overlying water environments, and these can also indirectly reflect the degree of eutrophication. In this paper, the spatial distribution characteristics of total organic carbon (TOC), total nitrogen (TN) and total phosphorus (TP) in the surface sediments of 11 sections in the lower Lancang River during flood season are analyzed, as well as the distribution of phosphorus in different forms. The main sources of TOC and its correlation with TN and TP are discussed and, finally, the pollution levels of the surface sediments are evaluated. The results show that the average content of TOC in the surface sediments of the lower Lancang River is 9003.75 mg/kg. The average TN content is 893.79 mg/kg, while the average TP content is 521.35 mg/kg. The TOC in the surface sediments of the lower Lancang River is derived mainly from algae and plankton in the river, and the TN and TP have similar sources. The total phosphorus in the surface sediments of the lower Lancang River is composed mainly of calcium-bound phosphorus (Ca-P). The evaluations of the organic pollution index and comprehensive pollution index show that the surface sediment pollution degree at the upper sections of the Nuozhadu and Jinghong Dams are more serious than those below the dams. Furthermore, the tributary sections are all slightly polluted, with the exception of the Mengyang River, which is considered moderately polluted.展开更多
The article Spatio-temporal changes in the six major glaciers of the Chitral River basin(Hindukush Region of Pakistan)between 2001 and 2018,written by Jawaria GUL,Sher MUHAMMAD,LIU Shi-yin,Siddique ULLAH,Shakeel AHMAD...The article Spatio-temporal changes in the six major glaciers of the Chitral River basin(Hindukush Region of Pakistan)between 2001 and 2018,written by Jawaria GUL,Sher MUHAMMAD,LIU Shi-yin,Siddique ULLAH,Shakeel AHMAD,Huma HAYAT and Adnan Ahmad TAHIR,was originally published Online First without Open Access.After publication in volume 17,issue 3,page 572-587,the author decided to opt for Open Choice and to make the article an Open Access publication.Therefore,the copyright of the article has been changed to C The Author(s)2020 and the article is forthwith distributed under the terms of the Creative Commons Attribution 4.0 International License(http://creativecommons.org/licenses/by/4.0/),which permits use,duplication,adaptation,distribution and reproduction in any medium or format,as long as you give appropriate credit to the original author(s)and the source,provide a link to the Creative Commons license,and indicate if changes were made.The original version of this article has been revised due to a retrospective Open Access order.展开更多
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 M...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.展开更多
A regional tree-ring width chronology of Schrenk spruce(Picea schrenkiana) was used to determine the annual(previous July to current June) streamflow of the Kuqa River in Xinjiang, China, for the period of 1414–2015....A regional tree-ring width chronology of Schrenk spruce(Picea schrenkiana) was used to determine the annual(previous July to current June) streamflow of the Kuqa River in Xinjiang, China, for the period of 1414–2015. A linear transformation of the tree-ring data accounted for 63.9% of the total variance when regressed against instrumental streamflow during 1957–2006. The model was validated by comparing the regression estimates against independent data. High streamflow periods with a streamflow above the 602-year mean occurred from 1430–1442, 1466–1492, 1557–1586, 1603–1615, 1687–1717, 1748–1767, 1795–1819, 1834–1856, 1888–1910 and 1989–2015. Low streamflow periods(streamflow below the mean) occurred from 1419–1429, 1443–1465, 1493–1556, 1587–1602, 1616–1686, 1720–1747, 1768–1794, 1820–1833, 1857–1887 and 1911–1988. The reconstruction compares well with the tree-ring-based streamflow series of the Tizinafu River from the Kunlun Mountains;both show well-known severe drought events. The streamflow reconstruction also shows highly synchronous upward trends since the 1980 s, suggesting that streamflow is related to Central Asian warming and humidification. Thus, the influences of the extremes and the persistence of low streamflows on local society may be considerable. Climatic changes in the watershed may be responsible for the change in the hydrologic regime of the Tarim Basin observed during the late twentieth century.展开更多
The Late Permian was marked by a series of important geological events and widespread organic-rich black shale depositions,acting as important unconventional hydrocarbon source rocks.However,the mechanism of organic m...The Late Permian was marked by a series of important geological events and widespread organic-rich black shale depositions,acting as important unconventional hydrocarbon source rocks.However,the mechanism of organic matter(OM)enrichment throughout this period is still controversial.Based on geochemical data,the marine redox conditions,paleogeographic and hydrographic environment,primary productivity,volcanism,and terrigenous input during the Late Permian in the Lower Yangtze region have been studied from the Putaoling section,Chaohu,to provide new insights into OM accumulation.Five Phases are distinguished based on the TOC and environmental variations.In Phase I,anoxic conditions driven by water restriction enhanced OM preservation.In Phase II,euxinic and cycling hydrological environments were the two most substantial controlling factors for the massive OM deposition.During Phase III,intensified terrestrial input potentially diluted the OM in sediment and the presence of oxygen in bottom water weakened the preservation condition.Phase IV was characterized by a relatively higher abundance of mercury(Hg)and TOC(peak at 16.98 wt%),indicating that enhanced volcanism potentially stimulated higher productivity and a euxinic environment.In Phase V,extremely lean OM was preserved as a result of terrestrial dilutions and decreasing primary productivity.Phases I,II and IV are characterized as the most prominent OM-rich zones due to the effective interactions of the controlling factors,namely paleogeographic,hydrographic environment,volcanism,and redox conditions.展开更多
The dual impact of climate change and human activities has precipitated a sharp decline in primate biodiversity globally.China is home to the most diverse primate species in the Northern hemisphere,which face severe e...The dual impact of climate change and human activities has precipitated a sharp decline in primate biodiversity globally.China is home to the most diverse primate species in the Northern hemisphere,which face severe ecological threats due to the expansion of modern agriculture,extensive exploitation and consumption of natural resources,and excessive land development during its transition from an agricultural to a modern society.In response,China has implemented various ecological conservation measures,including habitat restoration and protection.These efforts have made substantial strides in biodiversity conservation,with certain regions witnessing an increase in primate populations.In the current study,we conducted a systematic review of historical documents and field research data related to Chinese primates,evaluating the endangered status of primate species in China.Despite improvements in the habitats of most primate species and some population growth,many species still face severe threats,including declining and small populations.Species such as the Myanmar snub-nosed monkey(Rhinopithecus strykeri),eastern black crested gibbon(Nomascus nasutus),and Hainan gibbon(N.hainanus)remain particularly vulnerable due to their limited distribution ranges and extremely small populations.Insufficient scientific data,fragmented information,and not enough studies in conservation biology further compound the challenges.Moreover,there is a notable lack of detailed population monitoring data for species such as the Bengal slow loris(Nycticebus bengalensis),pygmy slow loris(N.pygmaeus),Indochinese gray langur(Trachypithecus crepusculus),Shortridge’s langur(T.shortridgei),and capped langur(T.pileatus),which hinders the development of practical and targeted conservation management strategies.Therefore,for national biodiversity conservation,there is an urgent need for specialized primate surveys,enhancing habitat protection and restoration,and increasing focus on cross-border conservation strategies and regional cooperation.There is also a need to establish a comprehensive and systematic research database platform,conduct continuous and in-depth research in primate biology,and actively engage in the scientific assessment of ecotourism.Additionally,strengthening public awareness and education on wildlife conservation remains essential.Such integrated and systematic efforts will provide scientific support for the current and future conservation and management of primate species in China.展开更多
Evaluating long-term changes in precipitation resources is important for accurate hydrological evaluation and forecasting,water security and rational allocation of water resources.For this purpose in the Xinjiang Haba...Evaluating long-term changes in precipitation resources is important for accurate hydrological evaluation and forecasting,water security and rational allocation of water resources.For this purpose in the Xinjiang Habahe area,tree-ring specimens were collected from Picea obovata,Larix sibirica,and Betula platyphylla to establish a tree-ring width chronology,which was used to analyse a correlation with the average temperature and precipitation per month for 1958-2016.Based on correlation coefficients for monthly temperature and precipitation with the chronology of tree-ring widths,radial tree growth was mainly restricted by precipitation,and tree-ring width chronology was significantly correlated with overall precipitation from the previous July to the next June(r=0.641,P<0.01).The above results were used to establish a transformation equation,and the overall precipitation from the previous July to the following June from 1800 to 2016 in Habahe was reconstructed after adjusted degrees of freedom,and obtain an explanatory rate of the variation up to 41.1%(40.0%).In addition to the reliability of the reconstructed values,the stability of the conversion function was determined via the“leave-one-out”method,which is commonly used in research on tree rings,and by cross-checking the conversion function with the reduced error value(RE),product mean test(t),with a sign test(ST).During the last 217 years,there were nine dry periods:1803-1829,1861-1865,1872-1885,1892-1905,1916-1923,1943-1954,1961-1966,1973-1981,and 2005-2011;and 12 wet periods:1830-1834,1836-1860,1866-1871,1886-1891,1906-1915,1925-1930,1934-1942,1955-1960,1967-1972,1982-1996,2000-2004,and 2012-2016.Comparisons of the reconstructions for neighboring regions and a spatial correlation analysis showed that the reconstructed sequence of the present precipitation data better represented the changes in precipitation in Habahe.Additionally,a power spectrum analysis revealed that precipitation over the past 217 years in Habahe Province exhibited 2-5 years of quasiperiodic variation.A power spectrum analysis and wavelet analysis indicated that El Niño-Southern Oscillation influenced the precipitation cycles.This reconstruction provides more information on high-frequency precipitation,which is an important supplement to the existing tree-ring reconstruction of precipitation in the study area.The reconstruction of regional high-resolution precipitation changes over the last several hundred years provides unique,important data for understanding regional differences in climate at the decadal-centennial scale.展开更多
The present work aims to assess earthquake-induced earth-retaining(ER)wall displacement.This study is on the dynamics analysis of various earth-retaining wall designs in hollow precast concrete panels,reinforcement co...The present work aims to assess earthquake-induced earth-retaining(ER)wall displacement.This study is on the dynamics analysis of various earth-retaining wall designs in hollow precast concrete panels,reinforcement concrete facing panels,and gravity-type earth-retaining walls.The finite element(FE)simulations utilized a 3D plane strain condition to model full-scale ER walls and numerous nonlinear dynamics analyses.The seismic performance of differentmodels,which includes reinforcement concrete panels and gravity-type and hollowprecast concrete ER walls,was simulated and examined using the FE approach.It also displays comparative studies such as stress distribution,deflection of the wall,acceleration across the wall height,lateral wall displacement,lateral wall pressure,and backfill plastic strain.Three components of the created ER walls were found throughout this research procedure.One is a granular reinforcement backfill,while the other is a wall-facing panel and base foundation.The dynamic response effects of varied earth-retaining walls have also been studied.It was discovered that the facing panel of the model significantly impacts the earthquake-induced displacement of ER walls.The proposed analytical model’s validity has been evaluated and compared with the reinforcement concrete facing panels,gravity-type ER wall,scientifically available data,and American Association of State Highway and Transportation Officials(AASHTO)guidelines results based on FE simulation.The results of the observations indicate that the hollow prefabricated concrete ER wall is the most feasible option due to its lower displacement and high-stress distribution compared to the two types.The methodology and results of this study establish standards for future analogous investigations and professionals,particularly in light of the increasing computational capabilities of desktop computers.展开更多
The China-Myanmar Economic Corridor(CMEC) is an important part of China's Belt and Road Initiative and an important area for global ecology and biodiversity. In this study, the annual and seasonal spatiotemporal p...The China-Myanmar Economic Corridor(CMEC) is an important part of China's Belt and Road Initiative and an important area for global ecology and biodiversity. In this study, the annual and seasonal spatiotemporal patterns of temperature and precipitation in the CMEC over the past century were investigated using linear tendency estimation, the Mann-Kendall mutation test, the T-test, and wavelet analysis based on the monthly mean climatic data from 1901 to 2018 released by the Climatic Research Unit(CRU) of the University of East Anglia, UK. The results show that the CMEC demonstrated a trend of warming and drying over the past 100 years, and the rate of change in Myanmar was stronger than that in Yunnan Province of China. The warming rate was 0.039 ℃/10a. Precipitation decreased at a rate of -6.1 mm/10a. From the perspective of spatial distribution, temperature was high in the central and southern, low in the north of the CMEC, and the high-temperature centers were mainly distributed in the southern plain and river valley. Precipitation decreased from west to east and from south to north of the CMEC. From the perspective of the rate of change, warming was stronger in central and northern CMEC than in southern and northeastern CMEC. The rate of precipitation decline was stronger in the central and western regions than in the eastern region. This study provides a scientific reference for the CMEC to address climate change and ensure sustainable social and economic development and ecological security.展开更多
Efficient iterative unsupervised machine learning involving probabilistic clustering analysis with the expectation-maximization(EM)clustering algorithm is applied to categorize reservoir facies by exploiting latent an...Efficient iterative unsupervised machine learning involving probabilistic clustering analysis with the expectation-maximization(EM)clustering algorithm is applied to categorize reservoir facies by exploiting latent and observable well-log variables from a clastic reservoir in the Majnoon oilfield,southern Iraq.The observable well-log variables consist of conventional open-hole,well-log data and the computer-processed interpretation of gamma rays,bulk density,neutron porosity,compressional sonic,deep resistivity,shale volume,total porosity,and water saturation,from three wells located in the Nahr Umr reservoir.The latent variables include shale volume and water saturation.The EM algorithm efficiently characterizes electrofacies through iterative machine learning to identify the local maximum likelihood estimates(MLE)of the observable and latent variables in the studied dataset.The optimized EM model developed successfully predicts the core-derived facies classification in two of the studied wells.The EM model clusters the data into three distinctive reservoir electrofacies(F1,F2,and F3).F1 represents a gas-bearing electrofacies with low shale volume(Vsh)and water saturation(Sw)and high porosity and permeability values identifying it as an attractive reservoir target.The results of the EM model are validated using nuclear magnetic resonance(NMR)data from the third studied well for which no cores were recovered.The NMR results confirm the effectiveness and accuracy of the EM model in predicting electrofacies.The utilization of the EM algorithm for electrofacies classification/cluster analysis is innovative.Specifically,the clusters it establishes are less rigidly constrained than those derived from the more commonly used K-means clustering method.The EM methodology developed generates dependable electrofacies estimates in the studied reservoir intervals where core samples are not available.Therefore,once calibrated with core data in some wells,the model is suitable for application to other wells that lack core data.展开更多
In the article“Influence of Various Earth-Retaining Walls on the Dynamic Response Comparison Based on 3D Modeling”by Muhammad Akba,Huali Pan,Jiangcheng Huang,Bilal Ahmed,Guoqiang Ou(Computer Modeling in Engineering&...In the article“Influence of Various Earth-Retaining Walls on the Dynamic Response Comparison Based on 3D Modeling”by Muhammad Akba,Huali Pan,Jiangcheng Huang,Bilal Ahmed,Guoqiang Ou(Computer Modeling in Engineering&Sciences,2024,Vol.139,No.3,2835–2863.DOI:10.32604/cmes.2024.046993,URL:https://www.techscience.com/CMES/v139n3/55652),one author’s affiliation was not included in the original article.展开更多
In widely studied organic-inorganic hybrid perovskites,the organic component tends to volatilize and decompose under high temperatures,oxygen,and humidity,which adversely affects the performance and longevity of the a...In widely studied organic-inorganic hybrid perovskites,the organic component tends to volatilize and decompose under high temperatures,oxygen,and humidity,which adversely affects the performance and longevity of the associated solar cells.In contrast,all-inorganic perovskites demonstrate superior stability under these conditions and offer photoelectric properties comparable to those of their hybrid counterparts.The potential of tandem solar cells(TSCs)made from all-inorganic perovskites is especially promising.This review is the first to address recent advancements in TSCs that use all-inorganic perovskites and crystalline silicon(c-Si),both domestically and internationally.This work provides a systematic and thorough analysis of the current challenges faced by these systems and proposes rational solutions.Additionally,we elucidate the regulatory mechanisms of all-inorganic perovskites and their TSCs when combined with c-Si,summarizing the corresponding patterns.Finally,we outline future research directions for all-inorganic perovskites and their TSCs with c-Si.This work offers valuable insights and references for the continued advancement of perovskitebased TSCs.展开更多
A macro-tidal tropical estuary with high fluvial discharge is characterized by both fragility and remarkable dynamism.This study utilizes the Salween River Delta(SRD)as a case example to examine the interplay between ...A macro-tidal tropical estuary with high fluvial discharge is characterized by both fragility and remarkable dynamism.This study utilizes the Salween River Delta(SRD)as a case example to examine the interplay between morphology and vegetation under similar tidal conditions.Our analysis of correlations and inferences revealed several significant trends in the SRD:(1)an overall expansion of land area and intertidal vegetation,with the most pronounced changes occurring in the eastern sector;(2)the predominance of river discharge influencing the southwestern and northern sectors,contrasted with the primary impact of storm surges in the eastern sector;and(3)three distinct causal relationships among estuarine morphology,vegetation,storm surges,and river discharge:a direct model where river discharge shapes estuarine morphology,a progressive model in which river discharge affects vegetation distribution,subsequently influencing estuarine morphology,and a hybrid model where storm surges directly impact vegetation and indirectly modify its distribution through changes in estuarine morphology.The stability of sediment supply and the role of intertidal vegetation are crucial for the continuous seaward advance,providing a vital foundation for the protection and development of estuarine deltas.展开更多
基金supported by the National Natural Science Foundation of China(42171129)the second Tibetan Plateau Scientific Expedition and Research(2019QZKK0208)Yunnan University Talent Introduction Research Project(YJRC3201702)。
文摘Land surface evapotranspiration(ET)is a critical component in the hydrological cycle but has not well been understood in data-scarce areas especially in river basins,like Nujiang River(NRB)which is characterized by large elevation gradient and different vegetation zones with complex processes of water and energy exchange.The quality of ET from optical remote sensing is constrained by cloud cover which is common in the NRB in the monsoon seasons.To understand factors controlling the spatial-temporal heterogeneity of ET in NRB,we employed the Variable Infiltration Capacity(VIC)hydrological model by parameter optimization with support of quality controlled remote sensing ET product and observed river runoff series in the river.The modeled ET has increased during 1984-2018,which might be one of the reasons for the runoff decrease but precipitation increase in the same period.ET increase and runoff decrease tended to be quicker within altitudinal band of 2000-4000 m than in other areas in NRB.We observed that ET variation in different climatic zones were controlled by different factors.ET is generally positively correlated with precipitation,temperature,and shortwave radiation but negatively with relative humidity.In the Tundra Climate(Et)zone in the upper reach of NRB,ET is controlled by precipitation,while it is controlled by shortwave radiation in the snow climate with dry winter(Dw)zone.ET increase is influenced by the increase of temperature,wind speed,and shortwave radiation in the middle and downstream of NRB with warm temperate climate,fully humid(Cf)and warm temperate climate with dry winter(Cw).
基金Under the auspices of the Yunnan Scientist Workstation on International River Research of Daming He(No.KXJGZS-2019-005)National Natural Science Foundation of China(No.42201040)+1 种基金National Key Research and Development Project of China(No.2016YFA0601601)China Postdoctoral Science Foundation(No.2023M733006)。
文摘Within the context of the Belt and Road Initiative(BRI)and the China-Myanmar Economic Corridor(CMEC),the Dulong-Ir-rawaddy(Ayeyarwady)River,an international river among China,India and Myanmar,plays a significant role as both a valuable hydro-power resource and an essential ecological passageway.However,the water resources and security exhibit a high degree of vulnerabil-ity to climate change impacts.This research evaluates climate impacts on the hydrology of the Dulong-Irrawaddy River Basin(DIRB)by using a physical-based hydrologic model.We crafted future climate scenarios using the three latest global climate models(GCMs)from Coupled Model Intercomparison Project 6(CMIP6)under two shared socioeconomic pathways(SSP2-4.5 and SSP5-8.5)for the near(2025-2049),mid(2050-2074),and far future(2075-2099).The regional model using MIKE SHE based on historical hydrologic processes was developed to further project future streamflow,demonstrating reliable performance in streamflow simulations with a val-idation Nash-Sutcliffe Efficiency(NSE)of 0.72.Results showed that climate change projections showed increases in the annual precip-itation and potential evapotranspiration(PET),with precipitation increasing by 11.3%and 26.1%,and PET increasing by 3.2%and 4.9%,respectively,by the end of the century under SSP2-4.5 and SSP5-8.5.These changes are projected to result in increased annual streamflow at all stations,notably at the basin’s outlet(Pyay station)compared to the baseline period(with an increase of 16.1%and 37.0%at the end of the 21st century under SSP2-4.5 and SSP5-8.5,respectively).Seasonal analysis for Pyay station forecasts an in-crease in dry-season streamflow by 31.3%-48.9%and 22.5%-76.3%under SSP2-4.5 and SSP5-8.5,respectively,and an increase in wet-season streamflow by 5.8%-12.6%and 2.8%-33.3%,respectively.Moreover,the magnitude and frequency of flood events are pre-dicted to escalate,potentially impacting hydropower production and food security significantly.This research outlines the hydrological response to future climate change during the 21st century and offers a scientific basis for the water resource management strategies by decision-makers.
基金Under the auspices of the National Natural Science Foundation of China(No.41661099)the National Key Research and Development Program of China(No.Grant 2016YFA0601601)
文摘Satellite-based precipitation products have been widely used to estimate precipitation, especially over regions with sparse rain gauge networks. However, the low spatial resolution of these products has limited their application in localized regions and watersheds.This study investigated a spatial downscaling approach, Geographically Weighted Regression Kriging(GWRK), to downscale the Tropical Rainfall Measuring Mission(TRMM) 3 B43 Version 7 over the Lancang River Basin(LRB) for 2001–2015. Downscaling was performed based on the relationships between the TRMM precipitation and the Normalized Difference Vegetation Index(NDVI), the Land Surface Temperature(LST), and the Digital Elevation Model(DEM). Geographical ratio analysis(GRA) was used to calibrate the annual downscaled precipitation data, and the monthly fractions derived from the original TRMM data were used to disaggregate annual downscaled and calibrated precipitation to monthly precipitation at 1 km resolution. The final downscaled precipitation datasets were validated against station-based observed precipitation in 2001–2015. Results showed that: 1) The TRMM 3 B43 precipitation was highly accurate with slight overestimation at the basin scale(i.e., CC(correlation coefficient) = 0.91, Bias = 13.3%). Spatially, the accuracies of the upstream and downstream regions were higher than that of the midstream region. 2) The annual downscaled TRMM precipitation data at 1 km spatial resolution obtained by GWRK effectively captured the high spatial variability of precipitation over the LRB. 3) The annual downscaled TRMM precipitation with GRA calibration gave better accuracy compared with the original TRMM dataset. 4) The final downscaled and calibrated precipitation had significantly improved spatial resolution, and agreed well with data from the validated rain gauge stations, i.e., CC = 0.75, RMSE(root mean square error) = 182 mm, MAE(mean absolute error) = 142 mm, and Bias = 0.78%for annual precipitation and CC = 0.95, RMSE = 25 mm, MAE = 16 mm, and Bias = 0.67% for monthly precipitation.
基金This work was supported by the National Key R&D Program of China (2018YFA0606401)NSFC (U1803341)+1 种基金the 2nd Scientific Expedition to the Qinghai-Tibet Plateau (No. 2019QZKK0102)the national youth talent support program
文摘A 606 year runoff reconstruction of the Kara Darya River was developed, based on the tree-ring width chronology of Turkestan juniper(Juniperus turkestanica) from the Pamir-Alai Mountains of Kyrgyzstan. Preliminary comparison between the snow cover variation and these climate/runoff reconstructions found that Central Asian snow cover may have strong associations with large-scale ocean-atmosphere-land circulations. The runoff reconstruction demonstrated that instrumental runoff was not representative of runoff over the past 606 years. The drought of the 1960 s-1990 s resulted in low runoff levels during the past 50 years;however, this probably does not represent a worst-case scenario for the Kara Darya because the runoff reconstruction showed additional extremely low runoff prior to the 20 th century. The reconstruction will provide a long-term perspective on runoff variation in the Kara Darya River basin, aid sustainable water resource management and be useful in guiding expectations of future variations and water resource planning.
基金Financial support for this research work by the National Natural Science Foundation of China(NSFC)and ICIMOD(Grant no.41761144075)is highly acknowledged。
文摘Glaciers in the northern Pakistan are a distinctive source of freshwater for the irrigation,drinking and industrial water supplies of the people living in those regions and downstream. These glaciers are under a direct global warming impact as indicated in many previous studies. In this study, we estimated the glacier dynamics in terms of Equilibrium Line Altitude(ELA), mass balance and the snout position variation using remote sensing data between 2001 and 2018. Six glaciers, having area≥ 20 km2 each, situated in the Chitral region(Hindukush Mountains) were investigated in this study. Digital Elevation Model(DEM) and available cloud-free continuous series of Landsat and Sentinel satellite images from minimum snow cover season were used to monitor the variability in the studied glaciers by keeping the status of glaciers in year 2001 as a reference. The annual climatic trends of mean temperature and total precipitation from Chitral weather station were detected using the nonparametric Mann-Kendall’s test. Results revealed a general increase in the ELA, decrease in the glacier mass balance and the retreat of snout position.Average upward shift in the ELA for the entire study area and data period was ~345 ± 93 m at a rate of^13 m.a-1 from the reference year’s position i.e.~4803 m asl. Estimated mean mass balance for the entire study area indicated a decline of-0.106 ± 0.295 m w.e. a-1. Periods of snout retreat and advance in different glaciers were found but the mean value over the entire study area was a retreat of-231 ± 140 m.No obvious relationship was found between the glacier variation trends and the available gauged climatic data possibly due to the presence of debris cover in ablation zones of all the studied glaciers which provides insulation and reduces the immediate climatic effects.
基金financially supported by the National Key Research and Development Program of China(No.2016YFA0601601)the National Science and Technology Support Program(No2013BAB06B03)the China Postdoctoral Science Foundation(No.2019M653506)
文摘Understanding the evolution of the fluvial geomorphology in an orogenic belt provides valuable insight into the relationship between upper crustal deformation and surface processes.The upper Lancang-Mekong River is in an area experiencing both uplift and erosion.The related processes provide a steady sediment supply to the lower reaches of the river and play an important role in the regional environmental changes.The Xiaohei(Weiyuan)River Basin is an important sub-basin in this area,which is characterized by large-scale topographic fluctuations,active tectonics and erosion,and anthropogenic activities.These different factors introduce numerous complexities to the local surface processes.In this study,we investigate and quantify the controls of geomorphic evolution of the Xiaohei River Basin.We located and mapped the main knick-zones within the channels and examined the main genetic factors,such as faults and stratigraphic differences.The results show that the areas with the lowest uplift rates are characterized by a low steepness index and are located in the southeastern part of the basin.The stream power of the mainstream increases downstream,with an average value of^122 W/m.The erosional activity of the various stream channels is intense.Overall,the basin tends to expansion,with only local instances of inward contraction.Our analysis confirms that a number of the geomorphic evolutionary characteristics of the Xiaohei River Basin are transient.In addition,the future potential for the increasing the number of dams and the hydropower development in the basin may weaken the expansion trend of the basin over a long period of time.
基金funded by the National Natural Science Foundation of China(Grant No.42061005,41661144044 and 41561003)the Science and Technology Projects of Yunnan Province(Grant No.202101AT070110)。
文摘The snow cover over the Qinghai-Tibet Plateau(QTP)and its surrounding areas is very sensitive to climate changes.Due to the complexity of geographical environment in this large region,the response of snow cover to climate change should exhibit spatiotemporal differences.In this study,the spatiotemporal variations of snow cover from 2002-2015 in the Yarlung Tsangpo-Brahmaputra River Basin(YBRB)were analyzed using an optimized fractional snow cover(FSC)product derived from Moderate Resolution Imaging Spectroradiometer(MODIS).Additionally,the effects of temperature and precipitation on the variability of snow cover were also investigated.The results showed that:(1)The snow cover exhibited large spatial and temporal heterogeneity in the YBRB.High FSC was observed in the northeast of the basin and the south slope of Himalaya,while the lowest was concentrated in the broad valley of the upstream of YBRB.The FSC value reached its highest in winter and dropped to its lowest in summer,but the monthly change processes were different between upstream and downstream regions.(2)A slightly increasing tendency(3.76%/10 a)of snow cover was observed on basin-wide,but the changes varied through time and space.The FSC increased significantly in the source and midstream regions during winter to spring(10.5%-18.0%/10 a),while it changed slightly in summer over all parts of the basin(-0.4%-4.3%/10 a).(3)The study area generally became warm and wet,and the change trend of temperature was more significant than that of precipitation.Snow cover changes were weakly correlated with temperature in winter and precipitation in summer.But in spring and autumn,both precipitation and temperature were significantly related to snow cover change in most regions of the basin.(4)The dominant factor driving the changes of snow cover varied in seasons.The area dominated by temperature was slightly larger than that dominated by precipitation in spring,except that precipitation significantly dominated the snow cover changes in the source region;In summer and autumn,temperature contributed more to the snow cover change in most areas of the basin;However,in winter,precipitation played a leading role in the variations of snow cover.These findings help to understand the different performance of the snow cover in the QTP and its surrounding areas under future climate change.
文摘Surface sediment is one of the main sources of nutrients in overlying water environments, and these can also indirectly reflect the degree of eutrophication. In this paper, the spatial distribution characteristics of total organic carbon (TOC), total nitrogen (TN) and total phosphorus (TP) in the surface sediments of 11 sections in the lower Lancang River during flood season are analyzed, as well as the distribution of phosphorus in different forms. The main sources of TOC and its correlation with TN and TP are discussed and, finally, the pollution levels of the surface sediments are evaluated. The results show that the average content of TOC in the surface sediments of the lower Lancang River is 9003.75 mg/kg. The average TN content is 893.79 mg/kg, while the average TP content is 521.35 mg/kg. The TOC in the surface sediments of the lower Lancang River is derived mainly from algae and plankton in the river, and the TN and TP have similar sources. The total phosphorus in the surface sediments of the lower Lancang River is composed mainly of calcium-bound phosphorus (Ca-P). The evaluations of the organic pollution index and comprehensive pollution index show that the surface sediment pollution degree at the upper sections of the Nuozhadu and Jinghong Dams are more serious than those below the dams. Furthermore, the tributary sections are all slightly polluted, with the exception of the Mengyang River, which is considered moderately polluted.
文摘The article Spatio-temporal changes in the six major glaciers of the Chitral River basin(Hindukush Region of Pakistan)between 2001 and 2018,written by Jawaria GUL,Sher MUHAMMAD,LIU Shi-yin,Siddique ULLAH,Shakeel AHMAD,Huma HAYAT and Adnan Ahmad TAHIR,was originally published Online First without Open Access.After publication in volume 17,issue 3,page 572-587,the author decided to opt for Open Choice and to make the article an Open Access publication.Therefore,the copyright of the article has been changed to C The Author(s)2020 and the article is forthwith distributed under the terms of the Creative Commons Attribution 4.0 International License(http://creativecommons.org/licenses/by/4.0/),which permits use,duplication,adaptation,distribution and reproduction in any medium or format,as long as you give appropriate credit to the original author(s)and the source,provide a link to the Creative Commons license,and indicate if changes were made.The original version of this article has been revised due to a retrospective Open Access order.
基金supported by the National Natural Science Foundation(Grant Nos.41301067,41671057,41671075)
文摘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.
基金This work is supported by the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDA20100306)the National Key R&D Program of China (Grant No. 2018YFA0606401)+1 种基金NSFC (Grant No. U1803341)the National Youth Talent Support Program and the Special Project for Key Laboratory of Autonomous Region (Grant No. 2017D04018)
文摘A regional tree-ring width chronology of Schrenk spruce(Picea schrenkiana) was used to determine the annual(previous July to current June) streamflow of the Kuqa River in Xinjiang, China, for the period of 1414–2015. A linear transformation of the tree-ring data accounted for 63.9% of the total variance when regressed against instrumental streamflow during 1957–2006. The model was validated by comparing the regression estimates against independent data. High streamflow periods with a streamflow above the 602-year mean occurred from 1430–1442, 1466–1492, 1557–1586, 1603–1615, 1687–1717, 1748–1767, 1795–1819, 1834–1856, 1888–1910 and 1989–2015. Low streamflow periods(streamflow below the mean) occurred from 1419–1429, 1443–1465, 1493–1556, 1587–1602, 1616–1686, 1720–1747, 1768–1794, 1820–1833, 1857–1887 and 1911–1988. The reconstruction compares well with the tree-ring-based streamflow series of the Tizinafu River from the Kunlun Mountains;both show well-known severe drought events. The streamflow reconstruction also shows highly synchronous upward trends since the 1980 s, suggesting that streamflow is related to Central Asian warming and humidification. Thus, the influences of the extremes and the persistence of low streamflows on local society may be considerable. Climatic changes in the watershed may be responsible for the change in the hydrologic regime of the Tarim Basin observed during the late twentieth century.
基金supported by the Fundamental and Commonwealth Geological Survey of Oil and Gas of China(Grant No.DD 20221662)the National Natural Science Foundation of China(NSFC)Program(Grant No.42302124).
文摘The Late Permian was marked by a series of important geological events and widespread organic-rich black shale depositions,acting as important unconventional hydrocarbon source rocks.However,the mechanism of organic matter(OM)enrichment throughout this period is still controversial.Based on geochemical data,the marine redox conditions,paleogeographic and hydrographic environment,primary productivity,volcanism,and terrigenous input during the Late Permian in the Lower Yangtze region have been studied from the Putaoling section,Chaohu,to provide new insights into OM accumulation.Five Phases are distinguished based on the TOC and environmental variations.In Phase I,anoxic conditions driven by water restriction enhanced OM preservation.In Phase II,euxinic and cycling hydrological environments were the two most substantial controlling factors for the massive OM deposition.During Phase III,intensified terrestrial input potentially diluted the OM in sediment and the presence of oxygen in bottom water weakened the preservation condition.Phase IV was characterized by a relatively higher abundance of mercury(Hg)and TOC(peak at 16.98 wt%),indicating that enhanced volcanism potentially stimulated higher productivity and a euxinic environment.In Phase V,extremely lean OM was preserved as a result of terrestrial dilutions and decreasing primary productivity.Phases I,II and IV are characterized as the most prominent OM-rich zones due to the effective interactions of the controlling factors,namely paleogeographic,hydrographic environment,volcanism,and redox conditions.
基金supported by the National Natural Science Foundation of China(32371563)and Strategic Priority Research Program of the Chinese Academy of Sciences(XDB31020302)。
文摘The dual impact of climate change and human activities has precipitated a sharp decline in primate biodiversity globally.China is home to the most diverse primate species in the Northern hemisphere,which face severe ecological threats due to the expansion of modern agriculture,extensive exploitation and consumption of natural resources,and excessive land development during its transition from an agricultural to a modern society.In response,China has implemented various ecological conservation measures,including habitat restoration and protection.These efforts have made substantial strides in biodiversity conservation,with certain regions witnessing an increase in primate populations.In the current study,we conducted a systematic review of historical documents and field research data related to Chinese primates,evaluating the endangered status of primate species in China.Despite improvements in the habitats of most primate species and some population growth,many species still face severe threats,including declining and small populations.Species such as the Myanmar snub-nosed monkey(Rhinopithecus strykeri),eastern black crested gibbon(Nomascus nasutus),and Hainan gibbon(N.hainanus)remain particularly vulnerable due to their limited distribution ranges and extremely small populations.Insufficient scientific data,fragmented information,and not enough studies in conservation biology further compound the challenges.Moreover,there is a notable lack of detailed population monitoring data for species such as the Bengal slow loris(Nycticebus bengalensis),pygmy slow loris(N.pygmaeus),Indochinese gray langur(Trachypithecus crepusculus),Shortridge’s langur(T.shortridgei),and capped langur(T.pileatus),which hinders the development of practical and targeted conservation management strategies.Therefore,for national biodiversity conservation,there is an urgent need for specialized primate surveys,enhancing habitat protection and restoration,and increasing focus on cross-border conservation strategies and regional cooperation.There is also a need to establish a comprehensive and systematic research database platform,conduct continuous and in-depth research in primate biology,and actively engage in the scientific assessment of ecotourism.Additionally,strengthening public awareness and education on wildlife conservation remains essential.Such integrated and systematic efforts will provide scientific support for the current and future conservation and management of primate species in China.
基金supported by the Natural Science Foundation of China(No.32061123008)Key Laboratory of Xinjiang Province of China(No.2022D04005)+2 种基金China Desert Weather Scientific Research Fund(Sqj2019002)Natural Science Foundation of Xinjiang Province of China(No.2021D01B118,2021D01B116)the Yunnan University Research Innovation Fund for Graduate Students(KC-22222199).
文摘Evaluating long-term changes in precipitation resources is important for accurate hydrological evaluation and forecasting,water security and rational allocation of water resources.For this purpose in the Xinjiang Habahe area,tree-ring specimens were collected from Picea obovata,Larix sibirica,and Betula platyphylla to establish a tree-ring width chronology,which was used to analyse a correlation with the average temperature and precipitation per month for 1958-2016.Based on correlation coefficients for monthly temperature and precipitation with the chronology of tree-ring widths,radial tree growth was mainly restricted by precipitation,and tree-ring width chronology was significantly correlated with overall precipitation from the previous July to the next June(r=0.641,P<0.01).The above results were used to establish a transformation equation,and the overall precipitation from the previous July to the following June from 1800 to 2016 in Habahe was reconstructed after adjusted degrees of freedom,and obtain an explanatory rate of the variation up to 41.1%(40.0%).In addition to the reliability of the reconstructed values,the stability of the conversion function was determined via the“leave-one-out”method,which is commonly used in research on tree rings,and by cross-checking the conversion function with the reduced error value(RE),product mean test(t),with a sign test(ST).During the last 217 years,there were nine dry periods:1803-1829,1861-1865,1872-1885,1892-1905,1916-1923,1943-1954,1961-1966,1973-1981,and 2005-2011;and 12 wet periods:1830-1834,1836-1860,1866-1871,1886-1891,1906-1915,1925-1930,1934-1942,1955-1960,1967-1972,1982-1996,2000-2004,and 2012-2016.Comparisons of the reconstructions for neighboring regions and a spatial correlation analysis showed that the reconstructed sequence of the present precipitation data better represented the changes in precipitation in Habahe.Additionally,a power spectrum analysis revealed that precipitation over the past 217 years in Habahe Province exhibited 2-5 years of quasiperiodic variation.A power spectrum analysis and wavelet analysis indicated that El Niño-Southern Oscillation influenced the precipitation cycles.This reconstruction provides more information on high-frequency precipitation,which is an important supplement to the existing tree-ring reconstruction of precipitation in the study area.The reconstruction of regional high-resolution precipitation changes over the last several hundred years provides unique,important data for understanding regional differences in climate at the decadal-centennial scale.
基金supported by Supported by the Science and Technology Research Program of the Institute of Mountain Hazards and Environment,CAS(IMHE-ZDRW-01)the National Natural Science Foundation of China,China(Grant Numbers:42077275&42271086)the Special Project of Basic Research-Key Project,Yunnan(Grant Number:202301AS070039).
文摘The present work aims to assess earthquake-induced earth-retaining(ER)wall displacement.This study is on the dynamics analysis of various earth-retaining wall designs in hollow precast concrete panels,reinforcement concrete facing panels,and gravity-type earth-retaining walls.The finite element(FE)simulations utilized a 3D plane strain condition to model full-scale ER walls and numerous nonlinear dynamics analyses.The seismic performance of differentmodels,which includes reinforcement concrete panels and gravity-type and hollowprecast concrete ER walls,was simulated and examined using the FE approach.It also displays comparative studies such as stress distribution,deflection of the wall,acceleration across the wall height,lateral wall displacement,lateral wall pressure,and backfill plastic strain.Three components of the created ER walls were found throughout this research procedure.One is a granular reinforcement backfill,while the other is a wall-facing panel and base foundation.The dynamic response effects of varied earth-retaining walls have also been studied.It was discovered that the facing panel of the model significantly impacts the earthquake-induced displacement of ER walls.The proposed analytical model’s validity has been evaluated and compared with the reinforcement concrete facing panels,gravity-type ER wall,scientifically available data,and American Association of State Highway and Transportation Officials(AASHTO)guidelines results based on FE simulation.The results of the observations indicate that the hollow prefabricated concrete ER wall is the most feasible option due to its lower displacement and high-stress distribution compared to the two types.The methodology and results of this study establish standards for future analogous investigations and professionals,particularly in light of the increasing computational capabilities of desktop computers.
基金funded by the Natural Science Foundation of China (Grant No. 42271030)Fujian Provincial Funds for Distinguished Young Scientists (Grant No. 2022J06018)Applied Basic Research Programs of Yunnan province (Grant No. 202001BB050073)。
文摘The China-Myanmar Economic Corridor(CMEC) is an important part of China's Belt and Road Initiative and an important area for global ecology and biodiversity. In this study, the annual and seasonal spatiotemporal patterns of temperature and precipitation in the CMEC over the past century were investigated using linear tendency estimation, the Mann-Kendall mutation test, the T-test, and wavelet analysis based on the monthly mean climatic data from 1901 to 2018 released by the Climatic Research Unit(CRU) of the University of East Anglia, UK. The results show that the CMEC demonstrated a trend of warming and drying over the past 100 years, and the rate of change in Myanmar was stronger than that in Yunnan Province of China. The warming rate was 0.039 ℃/10a. Precipitation decreased at a rate of -6.1 mm/10a. From the perspective of spatial distribution, temperature was high in the central and southern, low in the north of the CMEC, and the high-temperature centers were mainly distributed in the southern plain and river valley. Precipitation decreased from west to east and from south to north of the CMEC. From the perspective of the rate of change, warming was stronger in central and northern CMEC than in southern and northeastern CMEC. The rate of precipitation decline was stronger in the central and western regions than in the eastern region. This study provides a scientific reference for the CMEC to address climate change and ensure sustainable social and economic development and ecological security.
文摘Efficient iterative unsupervised machine learning involving probabilistic clustering analysis with the expectation-maximization(EM)clustering algorithm is applied to categorize reservoir facies by exploiting latent and observable well-log variables from a clastic reservoir in the Majnoon oilfield,southern Iraq.The observable well-log variables consist of conventional open-hole,well-log data and the computer-processed interpretation of gamma rays,bulk density,neutron porosity,compressional sonic,deep resistivity,shale volume,total porosity,and water saturation,from three wells located in the Nahr Umr reservoir.The latent variables include shale volume and water saturation.The EM algorithm efficiently characterizes electrofacies through iterative machine learning to identify the local maximum likelihood estimates(MLE)of the observable and latent variables in the studied dataset.The optimized EM model developed successfully predicts the core-derived facies classification in two of the studied wells.The EM model clusters the data into three distinctive reservoir electrofacies(F1,F2,and F3).F1 represents a gas-bearing electrofacies with low shale volume(Vsh)and water saturation(Sw)and high porosity and permeability values identifying it as an attractive reservoir target.The results of the EM model are validated using nuclear magnetic resonance(NMR)data from the third studied well for which no cores were recovered.The NMR results confirm the effectiveness and accuracy of the EM model in predicting electrofacies.The utilization of the EM algorithm for electrofacies classification/cluster analysis is innovative.Specifically,the clusters it establishes are less rigidly constrained than those derived from the more commonly used K-means clustering method.The EM methodology developed generates dependable electrofacies estimates in the studied reservoir intervals where core samples are not available.Therefore,once calibrated with core data in some wells,the model is suitable for application to other wells that lack core data.
文摘In the article“Influence of Various Earth-Retaining Walls on the Dynamic Response Comparison Based on 3D Modeling”by Muhammad Akba,Huali Pan,Jiangcheng Huang,Bilal Ahmed,Guoqiang Ou(Computer Modeling in Engineering&Sciences,2024,Vol.139,No.3,2835–2863.DOI:10.32604/cmes.2024.046993,URL:https://www.techscience.com/CMES/v139n3/55652),one author’s affiliation was not included in the original article.
基金the National Natural Science Foundation of China(Grant Nos.52164050 and 51762043)Major Science and Technology Project of Yunnan Province(Grant No.202202AB080010).
文摘In widely studied organic-inorganic hybrid perovskites,the organic component tends to volatilize and decompose under high temperatures,oxygen,and humidity,which adversely affects the performance and longevity of the associated solar cells.In contrast,all-inorganic perovskites demonstrate superior stability under these conditions and offer photoelectric properties comparable to those of their hybrid counterparts.The potential of tandem solar cells(TSCs)made from all-inorganic perovskites is especially promising.This review is the first to address recent advancements in TSCs that use all-inorganic perovskites and crystalline silicon(c-Si),both domestically and internationally.This work provides a systematic and thorough analysis of the current challenges faced by these systems and proposes rational solutions.Additionally,we elucidate the regulatory mechanisms of all-inorganic perovskites and their TSCs when combined with c-Si,summarizing the corresponding patterns.Finally,we outline future research directions for all-inorganic perovskites and their TSCs with c-Si.This work offers valuable insights and references for the continued advancement of perovskitebased TSCs.
基金National Natural Science Foundation of China,No.41906148,No.42271086Rejuvenating Yunnan Talents Support Plan Young Talent Program,No.XDYC-QNRC-2023-0322。
文摘A macro-tidal tropical estuary with high fluvial discharge is characterized by both fragility and remarkable dynamism.This study utilizes the Salween River Delta(SRD)as a case example to examine the interplay between morphology and vegetation under similar tidal conditions.Our analysis of correlations and inferences revealed several significant trends in the SRD:(1)an overall expansion of land area and intertidal vegetation,with the most pronounced changes occurring in the eastern sector;(2)the predominance of river discharge influencing the southwestern and northern sectors,contrasted with the primary impact of storm surges in the eastern sector;and(3)three distinct causal relationships among estuarine morphology,vegetation,storm surges,and river discharge:a direct model where river discharge shapes estuarine morphology,a progressive model in which river discharge affects vegetation distribution,subsequently influencing estuarine morphology,and a hybrid model where storm surges directly impact vegetation and indirectly modify its distribution through changes in estuarine morphology.The stability of sediment supply and the role of intertidal vegetation are crucial for the continuous seaward advance,providing a vital foundation for the protection and development of estuarine deltas.
