Climate change and anthropogenic activities have driven significant terrestrial water storage changes(TWSC)in the Three Rivers Source Region(TRSR),exerting profound impacts on freshwater availability across China and ...Climate change and anthropogenic activities have driven significant terrestrial water storage changes(TWSC)in the Three Rivers Source Region(TRSR),exerting profound impacts on freshwater availability across China and broader Asia.However,long-term TWSC characterization remains challenging due to limited observational data in this alpine region.Here,we integrate GRACE observations(2002-2020),ERA5-Land reanalysis,and GLDAS data to reconstruct TWSC using two methods:(1)the water balance method(PER)and(2)the component summation method(SS),applied to three input datasets(ERA5-Land,GLDAS,and their average,GLER).Comparative analysis reveals that the SS method applied to GL-ER yields the highest consistency with GRACE-derived TWSC.Using this optimal approach,we extend the analysis to 1951~2020,uncovering spatiotemporal TWSC patterns.Although annual TWSC trends appear negligible due to strong seasonality,we introduce the intra-year TWSC fluctuation(TWSCF)index to quantify cumulative variability.A significant(p<0.05)transition occurred in 1980,with TWSCF shifting from a declining trend(-0.39 mm/yr)to an increasing trend(0.56 mm/yr),primarily driven by soil moisture changes.However,Hurst exponent analysis suggests this upward trend may not persist.Drought and vegetation assessments indicate concurrent wetting and greening in the TRSR.TWSC correlates strongly with meteorological drought,acting as a reliable drought indicator while its linkage with vegetation dynamics suggests a potential contribution to greening.Our findings provide a robust framework for understanding long-term TWSC evolution and its hydrological-ecological interactions under climate change.展开更多
The source region of the Yellow River, accounting for over 38% of its total runoff, is a critical catchment area,primarily characterized by alpine grasslands. In 2005, the Maqu land surface processes observational sit...The source region of the Yellow River, accounting for over 38% of its total runoff, is a critical catchment area,primarily characterized by alpine grasslands. In 2005, the Maqu land surface processes observational site was established to monitor climate, land surface dynamics, and hydrological variability in this region. Over a 10-year period(2010–19), an extensive observational dataset was compiled, now available to the scientific community. This dataset includes comprehensive details on site characteristics, instrumentation, and data processing methods, covering meteorological and radiative fluxes, energy exchanges, soil moisture dynamics, and heat transfer properties. The dataset is particularly valuable for researchers studying land surface processes, land–atmosphere interactions, and climate modeling, and may also benefit ecological, hydrological, and water resource studies. The report ends with a discussion on perspectives and challenges of continued observational monitoring in this region, focusing on issues such as cryosphere influences, complex topography,and ecological changes like the encroachment of weeds and scrubland.展开更多
[Objectives]To explore the phylogenetic diversity of wetlands at the source of the Qin River and provide data reference for future research.[Methods]Taking survey data(July,2016)of plants in wetlands at the source of ...[Objectives]To explore the phylogenetic diversity of wetlands at the source of the Qin River and provide data reference for future research.[Methods]Taking survey data(July,2016)of plants in wetlands at the source of Qin River as research object,this study utilizes Phylocom 4.2 to construct plant(in wetlands at the source of Qin River)genealogical tree for 72 non-angiosperm species within research area,besides,the paper adopts Pedigree diversity index(PD),community pedigree structure index(net Relatedness index,NRI and Nearest Taxon Index,NTI)to analyze pedigree diversity and pedigree structure of plants in wetlands at the source of Qin River.This paper is going to explain the scientific question:pedigree diversity,pedigreeβdiversity,and pedigree structure of plants in wetlands at the source of Qin River,in order to study on relatedness and stability of community.[Results]The effect of habitat filtration will result in similar species adaptation and close genetic relationships in the community,manifesting as genealogy aggregation.On the contrary,the effect of competitive exclusion can lead to distant species genetic relationships in the community,manifesting as genealogy divergence.In this study,there was a tendency of aggregation among the species in sample plot S5,which indicated that the effect of habitat filtration was dominant in this plot,and in S2 and S6 the species had a decentralized trend.The NRI and NTI values in other plots were different in the positive and negative.[Conclusions]This research serves as an initial exploration of the phylogenetic diversity and community assembly mechanisms in the wetlands at the source of Qin River.Further studies incorporating environmental factors and human activities could provide deeper insights into community ecology phenomena and assembly mechanisms.展开更多
The mound-making behavior of plateau zokors is one of the most important factors in remodeling meadow microtopography and causing soil erosion in the Yellow River source area of western China,but little is known about...The mound-making behavior of plateau zokors is one of the most important factors in remodeling meadow microtopography and causing soil erosion in the Yellow River source area of western China,but little is known about the effects of microtopography on particle size characteristics(PSC)of eroded sediments from the bare slopes of zokor mounds during different rainfall events.In this study,we analyzed the relationship of microtopographic features derived from laser point cloud data and PSC of eroded sediments at six simulated rainfall intensities(all lasting 60 min).The effects of microtopography on PSC of eroded sediments were studied via partial least squares regression(PLSR)and structural equation modeling(SEM).The results showed that:(1)15-20 minutes from the beginning of rainfall was the sensitive period of soil loss from the slopes,and the function relationship between the rate of sediment and runoff and rainfall intensity can better predict the development trend of soil erosion;(2)Intense erosion occurred mainly in the upper half of the zokor mound,while deposition was mainly limited to its lower half.It is suggested that diminished plateau zokor activity intensity can effectively prevent and control soil erosion;(3)The PSC of eroded sediment is dominated by silt,followed by sand,with clay being the least abundant,and the eroded sediments with a particle size of 10-20μm were sensitive and highly susceptible to rainfall erosion.This finding facilitates the understanding of the formation process of surface geomorphology and the mechanism of soil erosion;(4)The PLSR model indicates that microtopography has an extensive influence on eroded sediments during hydraulic erosion,and the SEM analysis results further confirm that the fractal dimension was the best parameter to represent the PSC of eroded sediments,whereas surface cutting degree was the dominant factor controlling the PSC of eroded sediments.These findings are crucial for predicting soil erosion in the Yellow River source area and provide a new perspective for understanding soil erosion mechanisms in alpine meadow ecosystems.展开更多
In the restoration of degraded wetlands,fertilization can improve the vegetation-soil-microorganisms complex,thereby affecting the organic carbon content.However,it is currently unclear whether these effects are susta...In the restoration of degraded wetlands,fertilization can improve the vegetation-soil-microorganisms complex,thereby affecting the organic carbon content.However,it is currently unclear whether these effects are sustainable.This study employed Biolog-Eco surveys to investigate the changes in vegetation characteristics,soil physicochemical properties,and soil microbial functional diversity in degraded alpine wetlands of the source region of the Yellow River at 3 and 15 months after the application of nitrogen,phosphorus,and organic mixed fertilizer.The following results were obtained:The addition of nitrogen fertilizer and organic compost significantly affects the soil organic carbon content in degraded wetlands.Three months after fertilization,nitrogen addition increases soil organic carbon in both lightly and severely degraded wetlands,whereas after 15 months,organic compost enhanced the soil organic carbon level in severely degraded wetlands.Structural equation modeling indicates that fertilization decreases the soil pH and directly or indirectly influences the soil organic carbon levels through variations in the soil water content and the aboveground biomass of vegetation.Three months after fertilization,nitrogen fertilizer showed a direct positive effect on soil organic carbon.However,organic mixed fertilizer indirectly reduced soil organic carbon by increasing biomass and decreasing soil moisture.After 15 months,none of the fertilizers significantly affected the soil organic carbon level.In summary,it can be inferred that the addition of nitrogen fertilizer lacks sustainability in positively influencing the organic carbon content.展开更多
Summer precipitation in the Three Rivers Source Region(TRSR)of China is vital for the headwaters of the Yellow,Yangtze,and Lancang rivers and exhibits significant interdecadal variability.This study investigates the i...Summer precipitation in the Three Rivers Source Region(TRSR)of China is vital for the headwaters of the Yellow,Yangtze,and Lancang rivers and exhibits significant interdecadal variability.This study investigates the influence of the East Asian westerly jet(EAWJ)on TRSR rainfall.A strong correlation is found between TRSR summer precipitation and the Jet Zonal Position Index(JZPI)of the EAWJ from 1961 to 2019(R=0.619,p<0.01).During periods when a positive JZPI indicates a westward shift in the EAWJ,enhanced water vapor anomalies,warmer air,and low-level convergence anomalies contribute to increased TRSR summer precipitation.Using empirical orthogonal function and regression analyses,this research identifies the influence of large-scale circulation anomalies associated with the Atlantic–Eurasian teleconnection(AEA)from the North Atlantic(NA).The interdecadal variability between the NA and central tropical Pacific(CTP)significantly affects TRSR precipitation.This influence is mediated through the AEA via a Rossby wave train extending eastward along the EAWJ,and another south of 45°N.Moreover,the NA–CTP Opposite Phase Index(OPI),which quantifies the difference between the summer mean sea surface temperatures of the NA and the CTP,is identified as a critical factor in modulating the strength of this teleconnection and influencing the zonal position of the EAWJ.展开更多
Against the backdrop of global warming,the dynamics of glaciers and their water resources have significant implications for hydrological processes in the arid regions of Northwest China.The Aksu River,which is an esse...Against the backdrop of global warming,the dynamics of glaciers and their water resources have significant implications for hydrological processes in the arid regions of Northwest China.The Aksu River,which is an essential inland river enriched by substantial meltwater contributions,plays a pivotal role in the economic,ecological,and social development of the region.Based on 231 water samples collected during the period of intense glacial ablation in 2023,this study conducted a comprehensive analysis of the hydrochemical and stable isotopic characteristics of the Little Kurgan glacial basin in the Aksu River source region.A Piper diagram classified the hydrochemical type of the river water as Calcium-Bicarbonate.Analysis based on a Gibbs diagram indicated that rock weathering is the predominant factor affecting the hydrochemical properties within the studied basin.Through application of principal component analysis and end-member mixing analysis,it was determined that the glacier meltwater contribution to runoff was 67%,61%,and 55%in July,August,and September,respectively.The findings of this study reveal that glacier meltwater is the principal component of the river water,and highlight the critical impact of alterations in glacier ablation on the hydrological cycle within the Aksu River source region,which is vitally important for sustainable water resource management.展开更多
It is a key premise of ＇ecosystem approaches＇ to natural resources management that we must have an appropriate understanding of biodiversity values, and controls upon them, if we wish to manage them effectively. The...It is a key premise of ＇ecosystem approaches＇ to natural resources management that we must have an appropriate understanding of biodiversity values, and controls upon them, if we wish to manage them effectively. These biodiversity values, and associated ecosystem functionality, vary with space and time and are tied directly to landscape-scale relationships and evolutionary traits. In riverine systems, nested hierarchical principles provide a useful platform to assess relationships between landscape components across a range of scales. These understandings are most instructively synthesized through catchment-scale analyses. This paper outlines a rationale for systematic catchment-wide appraisals of river geodiversity. An initial application of these principles is presented for the Yellow River source zone in Qinghai Province, western China. Geo-ecological relationships are outlined for five broad sections of the trunk stream, highlighting implications for the management of these individual landscape compartments and for the system as a whole.展开更多
Twenty-four soil samples of eight ecosystem-types around the Yellow River source area were investigated for the number and specific composition of soil dematiaceous hyphomycetes by dilution plate technique. And then t...Twenty-four soil samples of eight ecosystem-types around the Yellow River source area were investigated for the number and specific composition of soil dematiaceous hyphomycetes by dilution plate technique. And then the co-relationship between genus species of soil dematiaceous hyphomycetes and ecosystem-types was analyzed. The results show that the amount and species distribution of soil dematiaceous hyphomycetes had an obvious variability in different ecosystem-types, and that the dominant genus species varied in the eight ecosystem-types studied, with Cladosporium being the dominant genus in seven of the eight ecosystem-types except wetland. The index of species diversity varied in different ecosystem-types. The niche breadth analysis showed that Cladosporium had the highest niche breadth and distributed in all ecosystem-types, while the genera with a narrow niche breadth distributed only in a few ecosystem-types. The results of niche overlap index analysis indicated that Stachybotrys and Torula, Doratomyces and Scolecobasidium, Cladosporium and Chrysosporium had a higher niche overlap, whereas Arthrinium and Gliomastix, Phialophora and Doratomyces, Oidiodendron and Ulocladium had no niche overlap.展开更多
The source region of the Yellow River is located in the middle east of the Tibetan Plateau in northwest China. The total area is about 51,700 km^2, mainly covered by grassland （79%）, unused land （16%） and water ...The source region of the Yellow River is located in the middle east of the Tibetan Plateau in northwest China. The total area is about 51,700 km^2, mainly covered by grassland （79%）, unused land （16%） and water （4%）. The increasing land utilization in this area has increased the risk of environmental degradation. The land use/cover data （1985 and 2000） provided by the Data Center of Resources and Environment in the Chinese Academy of Sciences were used to analyze the land cover change in the source region of the Yellow River. DEM （1：250,000） data, roads and settlement data were used to analyze the spatial characteristics of grasslands degradation. The ArcGIS 9 software was used to convert data types and do the overlay, reclassification and zonal statistic analysis. Results show that grassland degradation is the most important land cover change in the study area, which occupied 8.24% of the region＇s total area. Human activities are the main causes of the grassland degradation in the source region of the Yellow River： 1） the degradation rate is higher on the sunny slope than on the shady slope; 2） the grassland degradation rate decreases with an increase in the elevation, and it has a correlation coefficient of -0.93; 3） the nearer to the settlements the grassland is, the higher the degradation rate. Especially within a distance range of 12 km to the settlements, the grassland degradation rate is highly related with the distance, with a coefficient of -0.99; and 4） in the range of 4 km, the degradation rate decreases with the increase of distance to the roads, with a correlation coefficient of -0.98. Besides some physical factors, human activities have been the most important driving forces of the grassland degradation in the source region of the Yellow River since 1985. To resolve the degradation problems, population control is essential, and therefore, it can reduce the social demand of livestock products from the grassland. To achieve sustainable development, it needs to improve the management of grassland ecosystem.展开更多
Runoff coefficients of the source regions of the Huanghe River in 1956-2000 were analyzed in this paper. In the 1990s runoff of Tangnaihai Hydrologic Station of the Huanghe River experienced a serious decrease, which ...Runoff coefficients of the source regions of the Huanghe River in 1956-2000 were analyzed in this paper. In the 1990s runoff of Tangnaihai Hydrologic Station of the Huanghe River experienced a serious decrease, which had attracted considerable attention. Climate changes have important impact on the water resources availability. From the view of water cycling, runoff coefficients are important indexes of water resources in a particular catchment. Kalinin baseflow separation technique was improved based on the characteristics of precipitation and streamflow. After the separation of runoff coefficient （R/P）, baseflow coefficient （Br/P） and direct runoff coefficient （Dr/P） were estimated. Statistic analyses were applied to assessing the impact of precipitation and temperature on runoff coefficients （including Dr/P, Br/P and R/P）. The results show that in the source regions of the Huanghe River, mean annual baseflow coefficient was higher than mean annual direct runoff coefficient. Annual runoff coefficients were in direct proportion to annual precipitation and in inverse proportion to annual mean temperature. The decrease of runoff coefficients in the 1990s was closely related to the decrease in precipitation and increase in temperature in the same period. Over different sub-basins of the source regions of the Huanghe River, runoff coefficients responded differently to precipitation and temperature. In the area above Jimai Hydrologic Station where annual mean temperature is -3.9℃, temperature is the main factor influencing the runoff coefficients. Runoff coefficients were in inverse relation to temperature, and precipitation had nearly no impact on runoff coefficients. In subbasin between Jimai and Maqu Hydrologic Station Dr/P was mainly affected by precipitation while R/P and Br/P were both significantly influenced by precipitation and temperature. In the area between Maqu and Tangnaihai hydrologic stations all the three runoff coefficients increased with the rising of annual precipitation, while direct runoff coefficient was inversely proportional to temperature. In the source regions of the Huanghe River with the increase of average annual temperature, the impacts of temperature on runoff coefficients become insignificant.展开更多
Many observations in and model simulations for northern basins have confirmed an increased streamflow from degrading permafrost,while the streamflow has declined in the source area of the Yellow River(SAYR,above the T...Many observations in and model simulations for northern basins have confirmed an increased streamflow from degrading permafrost,while the streamflow has declined in the source area of the Yellow River(SAYR,above the Tanag hydrological station)on the northeastern Qinghai-Tibet Plateau,West China.How and to what extent does the degrading permafrost change the flow in the SAYR?According to seasonal regimes of hydrological processes,the SAYR is divided intofour sub-basins with varied permafrost extents to detect impacts of permafrost degradation on the Yellow River streamflow.Results show that permafrost degradation may have released appreciable meltwater for recharging groundwater.The potential release rate of ground-ice melt-water in the Sub-basin 1(the headwater area of the Yellow River(HAYR),above the Huangheyan hydrological station)is the highest(5.6 mm per year),contributing to 14.4%of the annual Yellow River streamflow at Huangheyan.Seasonal/intra-and annual shifts of streamflow,a possible signal for the marked alteration of hydrological processes by permafrost degradation,is observed in the HAYR,but the shifts are minor in other sub-basins in the SAYR.Improved hydraulic connectivity is expected to occur during and after certain degrees of permafrost degradation.Direct impacts of permafrost degradation on the annual Yellow River streamflow in the SAYR at Tanag,i.e.,from the meltwater of ground-ice,is estimated at 4.9%that of the annual Yellow River discharge at Tanag,yet with a high uncertainty,due to neglecting of the improved hydraulic connections from permafrost degradation and the flow generation conditions for the ground-ice meltwater.Enhanced evapotranspiration,substantial weakening of the Southwest China Autumn Rain,and anthropogenic disturbances may largely account for the declined streamflow in the SAYR.展开更多
There is growing concern over the effects of climate change on glacier melt and hydrology. In this article, we used two natural small-scale basins, Tuotuo River and Buqu River in the source region of the Yangtze River...There is growing concern over the effects of climate change on glacier melt and hydrology. In this article, we used two natural small-scale basins, Tuotuo River and Buqu River in the source region of the Yangtze River, China, to show the impacts of glacier melt on stream flow. Changes in the extent of glaciers and ice volume in 1970, 1992 and 2009 are evaluated using remote sensing images. Changes to the glacier surface area over the same time interval are estimated through the delineation of glacier outlines and positions using Landsat TM/ETM＋ imagery. By 2009, the glacier surface area had decreased by 20.83% and 34.81% of the 1970 values in Tuotuo River and Baqu River basins respectively. The total meltwater supply in each basin is estimated to be 2.56×10^9 m^3/yr and 1.24×10^9 m^3/yr respectively. Mass balance calculations show that glaciers in the study area suffered a constant mass loss of snow and ice, accumulatively approximately -24 m over the past 40 years. The annual and summer stream flow tended to increase in Tuotuo River basin from 1970 to 2009 while a negative trend of change was shown in Buqu River basin during 1970-1986. Glaciers became shorter, narrower and thinner under the effect of atmospheric warming. Streamflow increase has been recorded at Tuotuo River station in response to increased glacier and permafrost melt. However, streamflow decrease has been recorded at Yanshiping station on Buqu River, where glacier melt has lagged behind atmospheric warming. These results show a close but variable linkage among climate change, glacier melting and water resources in the source region of the Yangtze River.展开更多
Precipitation, a natural feature of weather systems in the Earth, is vitally important for the environment of any region. Under global climate change condition, the characteristics of precipitation have changed as a c...Precipitation, a natural feature of weather systems in the Earth, is vitally important for the environment of any region. Under global climate change condition, the characteristics of precipitation have changed as a consequence of enhanced global hydrological cycle. The source region of the Yellow River（SRYR）, locating within the Qinghai-Tibet Plateau, is sensitive to the global climate change due to its complex orography and fragile ecosystem. To understand the precipitation characteristics and its impacts on the environment in the region, we studied the characteristics of rainy days and precipitation amount of different precipitation classes, such as light（0–5 and 5–10 mm）, moderate（10–15, 15–20 and 20–25 mm） and heavy（≥25 mm） rains by analyzing the precipitation data of typical meteorological stations in the SRYR during the period 1961–2014, as well as the trends of persistent rainfall events and drought events. Results showed that annual average precipitation in this area had a non-significant（P〉0.05） increasing trend, and 82.5% of the precipitation occurred from May to September. Rainy days of the 0–5 mm precipitation class significantly decreased, whereas the rainy days of 5–10, 10–15, and 20–25 mm precipitation classes increased and that of ≥25 mm precipitation class decreased insignificantly. The persistent rainfall events of 1-or 2-day and more than 2-day showed an increasing trend, with the 1-or 2-day events being more frequent. Meanwhile, the number of short drought periods（≤10 days） increased while long drought periods（〉10 days） decreased. Since the 0–5 mm precipitation class had a huge impact on the grasslands productivity; the 5–10, 10–15, and 20–25 mm precipitation classes had positive effects on vegetation which rely on the deep soil water through moving nutrients and water into the root zone of these vegetation or through the plant-microbe interactions; the ≥25 mm precipitation class contributed to the floods; and more persistent rainfall events and fewer long drought events inferred positive effects on agriculture. Thus, these results indicate grassland degradation, less risk of floods, and the upgrading impact of climate change on agriculture. This study may provide scientific knowledge for policymakers to sustain the eco-environmental resources in the SYSR.展开更多
The Yangtze River Source Region has an area of 137,704 km2.Its mean annual runoff of 12.52 billion m3,which was recorded by the Chumda Hydrological Station in 1961–2000,accounts for only 0.13 percent of the Yangtze R...The Yangtze River Source Region has an area of 137,704 km2.Its mean annual runoff of 12.52 billion m3,which was recorded by the Chumda Hydrological Station in 1961–2000,accounts for only 0.13 percent of the Yangtze River's total annual streamflow.The extensive rivers,lakes,wetlands,glaciers,snow fields,and permafrost of the Yangtze River Source Region,as well as the region's vast alpine grasslands,play a critical role in storing and regulating the flow of water not only in the upper Yangtze River watershed of Qinghai,Sichuan,the Tibet Autonomous Region (TAR) (Tibet) and Yunnan,but also throughout the entire lower Yangtze River basin.Climate change has been the dominant factor in recent fluctuation in the volume of the Yangtze River Source Region's glacier resources.The Chumda Hydrological Station on the lower Tongtian River has registered a mean annual glacial meltwater of 1.13 billion m3 for the period 1961–2000,makes up 9 percent of the total annual runoff.Glacial meltwater makes up a significant percentage of streamflow in the Yangtze River Source Region,the major rivers of the upper Yangtze River Source Region:the Togto,Dam Chu,Garchu,and Bi Chu (Bu Chu) rivers all originate at large glaciers along the Tanggula Range.Glaciers in the Yangtze River Source Region are typical continental-type glaciers with most glacial meltwater flow occurring June–August;the close correlation between June–August river flows and temperature illustrates the important role of glacial meltwater in feeding rivers.Glaciers in the source region have undergone a long period of rapid ablation beginning in 1993.Examination of flow and temperature data for the 1961–2000 period shows that the annual melting period for glacial ice,snow,and frozen ground in the Yangtze River Source Region now begins earlier because of increasing spring temperatures,resulting in the reduction of summer flood season peak runoffs;meanwhile,increased rates of glacier ablation have resulted in more uneven annual distribution of runoff in the source region.The annual glacial meltwater runoff in the Yangtze River Source Region is projected to increase by 28.5 percent by 2050 over its 1970 value with the projected temperature increase of 2℃ and a precipitation increase of 29 mm.As a critical source of surface water for agriculture on the eastern Qinghai-Tibet Plateau and beyond,the mass retreat of glaciers in the Yangtze River Source Region will have enormous negative impacts on farming and livestock-raising ac-tivities in upper Yangtze River watershed,as well as on the viability of present ecosystems and even socioeconomic development in the upper Yangtze River Basin.展开更多
This study examines the hydrological and meteorological data of the source region of the Yellow River from 1956 to 2010 and future climate scenarios from regional climate model （PRECIS） during 2010-2020. Through ana...This study examines the hydrological and meteorological data of the source region of the Yellow River from 1956 to 2010 and future climate scenarios from regional climate model （PRECIS） during 2010-2020. Through analyzing the flow variations and revealing the climate causes, it predicts the variation trend for future flows. It is found that the annual mean flow showed a decreasing trend in recent 50 years in the source region of the Yellow River with quasi-periods of 5a, 8a, 15a, 22a and 42a; the weakened South China Sea summer monsoon induced precipitation decrease, as well as evaporation increase and frozen soil degeneration in the scenario of global warming are the climate factors, which have caused flow decrease. Based on the regional climate model PRECIS prediction, the flows in the source region of the Yellow River are likely to decrease generally in the next 20 years.展开更多
Climate change investigation at a watershed-scale plays a significant role in re- vealing the historical evolution and future trend of the runoff variation in watershed. This study examines the multisource hydrologica...Climate change investigation at a watershed-scale plays a significant role in re- vealing the historical evolution and future trend of the runoff variation in watershed. This study examines the multisource hydrological and meteorological variables over the source area of the Yellow River （SAYR） from 1961 to 2,012 and the future climate scenarios in the region during 2006-2100 based on the CMIP5 projection data. It recognizes the significant charac-teristics of the recent climate change in the SAYR and predicts the change trend of future flow in the region. It is found that （1） The climate in the SAYR has experienced a significant warm-wet change since the early 2000s, which is very different from the antecedent warm-dry trend since the late 1980s; （2） The warm-wet trend in the northwestern SAYR （the headwater area of the Yellow River （HAYR）, is more obvious than that in the whole SAYR; （3） With pre- cipitation increase, the runoff in the region also experienced an increasing process since 2006. The runoff variations in the region are sensitive to the changes of precipitation, PET and maximum air temperature, but not very sensitive to changes in mean and minimum air temperatures; （4） Based on the CMIP5 projection data, the warm-wet climate trend in SAYR are likely to continue until 2049 if considering three different （i.e. RCP2.6, RCP4.5 and RCP8.5） greenhouse gas emission scenarios, and the precipitation in SAYR will not be less than the current level before 2100; however, it is estimated that the recent flow increase in the SAYR is likely to be the decadal change and it will at most continue until the 2020s; （5） The inter-annual variations of the East Asian winter monsoon are found to be closely related to the variations of annual precipitation in the region. Meanwhile, the increased precipitation as well as the increase of potential evapotranspiration （PET） being far less than that of precipitation in the recent period are the main climate causes for the flow increase in the region.展开更多
After dividing the source regions of the Yellow River into 38 sub-basins, thepaper made use of the SWAT model to simulate streamflow with validation and calibration of theobserved yearly and monthly runoff data from t...After dividing the source regions of the Yellow River into 38 sub-basins, thepaper made use of the SWAT model to simulate streamflow with validation and calibration of theobserved yearly and monthly runoff data from the Tangnag hydrological station, and simulationresults are satisfactory. Five land-cover scenario models and 24 sets of temperature andprecipitation combinations were established to simulate annual runoff and runoff depth underdifferent scenarios. The simulation shows that with the increasing of vegetation coverage annualrunoff increases and evapotranspiration decreases in the basin. When temperature decreases by 2℃and precipitation increases by 20%, catchment runoff will increase by 39.69%, which is the largestsituation among all scenarios.展开更多
Taking the source region of the Yellow River as a study area and based on the data from Madoi Meteorological Station and Huangheyan Hydrological Station covering the period 1955-2005, this paper analyses the changing ...Taking the source region of the Yellow River as a study area and based on the data from Madoi Meteorological Station and Huangheyan Hydrological Station covering the period 1955-2005, this paper analyses the changing trends of surface water resources, climate and frozen ground and reveals their causes. Results show that there exist frequent fluctuations from high to low water flow in the 51-year period. In general, the discharge has shown a de- clining trend in the 51 years especially since the 1990s. The annual distribution shows one peak which, year on year is getting smaller. （1） Precipitation has a significant and sustained influence on discharge. （2） A sharp rise of temperature resulted in the increase of evaporation and the decrease of discharge, which has a greater effect than on ice-snow melting. （3） Frozen ground tends to be degraded markedly. There is a significant positive correlation be- tween the permafrost thickness and the discharge. （4） Evaporation rates are significantly increasing, leading to the decrease of discharge. 70% of the discharge reduction resulted from climate change, and the remaining 30% may have been caused by human activities.展开更多
The interaction among different livelihood capitals is a key to generate a deeper understanding of the livelihood sustainability.In this paper,we use net income per capita(economic capital),meat and milk production pe...The interaction among different livelihood capitals is a key to generate a deeper understanding of the livelihood sustainability.In this paper,we use net income per capita(economic capital),meat and milk production per capita(physical capital),and areas of fenced pasture,livestock shelter,grassland rodent control and planted grassland(physical capital) as proxy indicators of livelihood promotion,livelihood provision,and livelihood protection respectively.By developing a correlation model between pastoralists' livelihood protection and improvement,we found that(1) there is a statistically significant correlation between the pastoralists' livelihood protection and promotion;(2) based on the maximum effect of pastoralists' livelihood promotion and provision,there is a benchmark in the effect of the intervention intensity of livelihood capital(grassland resource protection) on livelihood improvement;(3) on basis of two indicators,i.e.net income per capita and meat production per capita,the reasonable scales of fenced pasture,livestock shelter and planted grassland are less than 843,860 and 46 thousand hectares(hm2) per year respectively.With the marginal effect of livelihood protection,moderately decreased areas of fenced pasture and planted grassland,and increased area of livestock shelter is a critical to ensure pastoralist's livelihood sustainability.展开更多
基金funded by the Postdoctoral Research Startup Foundation of University of Jinan(Grant No.100389917).
文摘Climate change and anthropogenic activities have driven significant terrestrial water storage changes(TWSC)in the Three Rivers Source Region(TRSR),exerting profound impacts on freshwater availability across China and broader Asia.However,long-term TWSC characterization remains challenging due to limited observational data in this alpine region.Here,we integrate GRACE observations(2002-2020),ERA5-Land reanalysis,and GLDAS data to reconstruct TWSC using two methods:(1)the water balance method(PER)and(2)the component summation method(SS),applied to three input datasets(ERA5-Land,GLDAS,and their average,GLER).Comparative analysis reveals that the SS method applied to GL-ER yields the highest consistency with GRACE-derived TWSC.Using this optimal approach,we extend the analysis to 1951~2020,uncovering spatiotemporal TWSC patterns.Although annual TWSC trends appear negligible due to strong seasonality,we introduce the intra-year TWSC fluctuation(TWSCF)index to quantify cumulative variability.A significant(p<0.05)transition occurred in 1980,with TWSCF shifting from a declining trend(-0.39 mm/yr)to an increasing trend(0.56 mm/yr),primarily driven by soil moisture changes.However,Hurst exponent analysis suggests this upward trend may not persist.Drought and vegetation assessments indicate concurrent wetting and greening in the TRSR.TWSC correlates strongly with meteorological drought,acting as a reliable drought indicator while its linkage with vegetation dynamics suggests a potential contribution to greening.Our findings provide a robust framework for understanding long-term TWSC evolution and its hydrological-ecological interactions under climate change.
基金supported by the National Natural Science Foundation of China for Distinguished Young Scholars (Grant No.42325502)the 2nd Scientific Expedition to the Qinghai–Tibet Plateau (Grant No.2019QZKK0102)+3 种基金the West Light Foundation of the Chinese Academy of Sciences (Grant No.xbzg-zdsys-202215)the Science and Technology Research Plan of Gansu Province (Grant Nos.23JRRA654 and 20JR10RA070)the Youth Innovation Promotion Association of the Chinese Academy of Sciences (Grant No.QCH2019004)iLEAPS (integrated Land Ecosystem–Atmosphere Processes Study)。
文摘The source region of the Yellow River, accounting for over 38% of its total runoff, is a critical catchment area,primarily characterized by alpine grasslands. In 2005, the Maqu land surface processes observational site was established to monitor climate, land surface dynamics, and hydrological variability in this region. Over a 10-year period(2010–19), an extensive observational dataset was compiled, now available to the scientific community. This dataset includes comprehensive details on site characteristics, instrumentation, and data processing methods, covering meteorological and radiative fluxes, energy exchanges, soil moisture dynamics, and heat transfer properties. The dataset is particularly valuable for researchers studying land surface processes, land–atmosphere interactions, and climate modeling, and may also benefit ecological, hydrological, and water resource studies. The report ends with a discussion on perspectives and challenges of continued observational monitoring in this region, focusing on issues such as cryosphere influences, complex topography,and ecological changes like the encroachment of weeds and scrubland.
文摘[Objectives]To explore the phylogenetic diversity of wetlands at the source of the Qin River and provide data reference for future research.[Methods]Taking survey data(July,2016)of plants in wetlands at the source of Qin River as research object,this study utilizes Phylocom 4.2 to construct plant(in wetlands at the source of Qin River)genealogical tree for 72 non-angiosperm species within research area,besides,the paper adopts Pedigree diversity index(PD),community pedigree structure index(net Relatedness index,NRI and Nearest Taxon Index,NTI)to analyze pedigree diversity and pedigree structure of plants in wetlands at the source of Qin River.This paper is going to explain the scientific question:pedigree diversity,pedigreeβdiversity,and pedigree structure of plants in wetlands at the source of Qin River,in order to study on relatedness and stability of community.[Results]The effect of habitat filtration will result in similar species adaptation and close genetic relationships in the community,manifesting as genealogy aggregation.On the contrary,the effect of competitive exclusion can lead to distant species genetic relationships in the community,manifesting as genealogy divergence.In this study,there was a tendency of aggregation among the species in sample plot S5,which indicated that the effect of habitat filtration was dominant in this plot,and in S2 and S6 the species had a decentralized trend.The NRI and NTI values in other plots were different in the positive and negative.[Conclusions]This research serves as an initial exploration of the phylogenetic diversity and community assembly mechanisms in the wetlands at the source of Qin River.Further studies incorporating environmental factors and human activities could provide deeper insights into community ecology phenomena and assembly mechanisms.
基金financially supported by the Qinghai University Graduate Student Research and Practice Innovation Project(2025-GPKY-12)Basic Research Project of Qinghai Provincial Science and Technology Department(2021-ZJ-701)+1 种基金National Natural Science Foundation of China(U23A20159,42161068)the 111 Project of China(D18013)。
文摘The mound-making behavior of plateau zokors is one of the most important factors in remodeling meadow microtopography and causing soil erosion in the Yellow River source area of western China,but little is known about the effects of microtopography on particle size characteristics(PSC)of eroded sediments from the bare slopes of zokor mounds during different rainfall events.In this study,we analyzed the relationship of microtopographic features derived from laser point cloud data and PSC of eroded sediments at six simulated rainfall intensities(all lasting 60 min).The effects of microtopography on PSC of eroded sediments were studied via partial least squares regression(PLSR)and structural equation modeling(SEM).The results showed that:(1)15-20 minutes from the beginning of rainfall was the sensitive period of soil loss from the slopes,and the function relationship between the rate of sediment and runoff and rainfall intensity can better predict the development trend of soil erosion;(2)Intense erosion occurred mainly in the upper half of the zokor mound,while deposition was mainly limited to its lower half.It is suggested that diminished plateau zokor activity intensity can effectively prevent and control soil erosion;(3)The PSC of eroded sediment is dominated by silt,followed by sand,with clay being the least abundant,and the eroded sediments with a particle size of 10-20μm were sensitive and highly susceptible to rainfall erosion.This finding facilitates the understanding of the formation process of surface geomorphology and the mechanism of soil erosion;(4)The PLSR model indicates that microtopography has an extensive influence on eroded sediments during hydraulic erosion,and the SEM analysis results further confirm that the fractal dimension was the best parameter to represent the PSC of eroded sediments,whereas surface cutting degree was the dominant factor controlling the PSC of eroded sediments.These findings are crucial for predicting soil erosion in the Yellow River source area and provide a new perspective for understanding soil erosion mechanisms in alpine meadow ecosystems.
基金supported by the National Nature Science Foundations of China(32160269)the International Science and Technology Cooperation Project of Qinghai province of China(2022-HZ-817).
文摘In the restoration of degraded wetlands,fertilization can improve the vegetation-soil-microorganisms complex,thereby affecting the organic carbon content.However,it is currently unclear whether these effects are sustainable.This study employed Biolog-Eco surveys to investigate the changes in vegetation characteristics,soil physicochemical properties,and soil microbial functional diversity in degraded alpine wetlands of the source region of the Yellow River at 3 and 15 months after the application of nitrogen,phosphorus,and organic mixed fertilizer.The following results were obtained:The addition of nitrogen fertilizer and organic compost significantly affects the soil organic carbon content in degraded wetlands.Three months after fertilization,nitrogen addition increases soil organic carbon in both lightly and severely degraded wetlands,whereas after 15 months,organic compost enhanced the soil organic carbon level in severely degraded wetlands.Structural equation modeling indicates that fertilization decreases the soil pH and directly or indirectly influences the soil organic carbon levels through variations in the soil water content and the aboveground biomass of vegetation.Three months after fertilization,nitrogen fertilizer showed a direct positive effect on soil organic carbon.However,organic mixed fertilizer indirectly reduced soil organic carbon by increasing biomass and decreasing soil moisture.After 15 months,none of the fertilizers significantly affected the soil organic carbon level.In summary,it can be inferred that the addition of nitrogen fertilizer lacks sustainability in positively influencing the organic carbon content.
基金supported by the 2nd Scientific Expedition to the Qinghai–Tibet Plateau[grant number 2019QZKK0102]the National Natural Science Foundation of China[grant number 42275045,41975012]+3 种基金the West Light Foundation of the Chinese Academy of Sciences[grant number xbzg-zdsys-202215]the Science and Technology Research Plan of Gansu Province[grant number 20JR10RA070]the Youth Innovation Promotion Association of the Chinese Academy of Sciences[grant number QCH2019004]iLEAPs(integrated Land Ecosystem–Atmosphere Processes Study).
文摘Summer precipitation in the Three Rivers Source Region(TRSR)of China is vital for the headwaters of the Yellow,Yangtze,and Lancang rivers and exhibits significant interdecadal variability.This study investigates the influence of the East Asian westerly jet(EAWJ)on TRSR rainfall.A strong correlation is found between TRSR summer precipitation and the Jet Zonal Position Index(JZPI)of the EAWJ from 1961 to 2019(R=0.619,p<0.01).During periods when a positive JZPI indicates a westward shift in the EAWJ,enhanced water vapor anomalies,warmer air,and low-level convergence anomalies contribute to increased TRSR summer precipitation.Using empirical orthogonal function and regression analyses,this research identifies the influence of large-scale circulation anomalies associated with the Atlantic–Eurasian teleconnection(AEA)from the North Atlantic(NA).The interdecadal variability between the NA and central tropical Pacific(CTP)significantly affects TRSR precipitation.This influence is mediated through the AEA via a Rossby wave train extending eastward along the EAWJ,and another south of 45°N.Moreover,the NA–CTP Opposite Phase Index(OPI),which quantifies the difference between the summer mean sea surface temperatures of the NA and the CTP,is identified as a critical factor in modulating the strength of this teleconnection and influencing the zonal position of the EAWJ.
基金National Natural Science Foundation of China,No.42071076,No.41501085Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions,No.PAPD-20181105Jiangsu Normal University Support Fund for Doctoral Teachers Research,No.17XLR002。
文摘Against the backdrop of global warming,the dynamics of glaciers and their water resources have significant implications for hydrological processes in the arid regions of Northwest China.The Aksu River,which is an essential inland river enriched by substantial meltwater contributions,plays a pivotal role in the economic,ecological,and social development of the region.Based on 231 water samples collected during the period of intense glacial ablation in 2023,this study conducted a comprehensive analysis of the hydrochemical and stable isotopic characteristics of the Little Kurgan glacial basin in the Aksu River source region.A Piper diagram classified the hydrochemical type of the river water as Calcium-Bicarbonate.Analysis based on a Gibbs diagram indicated that rock weathering is the predominant factor affecting the hydrochemical properties within the studied basin.Through application of principal component analysis and end-member mixing analysis,it was determined that the glacier meltwater contribution to runoff was 67%,61%,and 55%in July,August,and September,respectively.The findings of this study reveal that glacier meltwater is the principal component of the river water,and highlight the critical impact of alterations in glacier ablation on the hydrological cycle within the Aksu River source region,which is vitally important for sustainable water resource management.
基金National Natural Science Foundation of China, No.41001008 International Science ＆ Technology Cooperation Program of China, No.2011DFG93160 No.2011DFA20820
文摘It is a key premise of ＇ecosystem approaches＇ to natural resources management that we must have an appropriate understanding of biodiversity values, and controls upon them, if we wish to manage them effectively. These biodiversity values, and associated ecosystem functionality, vary with space and time and are tied directly to landscape-scale relationships and evolutionary traits. In riverine systems, nested hierarchical principles provide a useful platform to assess relationships between landscape components across a range of scales. These understandings are most instructively synthesized through catchment-scale analyses. This paper outlines a rationale for systematic catchment-wide appraisals of river geodiversity. An initial application of these principles is presented for the Yellow River source zone in Qinghai Province, western China. Geo-ecological relationships are outlined for five broad sections of the trunk stream, highlighting implications for the management of these individual landscape compartments and for the system as a whole.
基金Project (No. 30670014) supported by the National Natural Science Foundation of China
文摘Twenty-four soil samples of eight ecosystem-types around the Yellow River source area were investigated for the number and specific composition of soil dematiaceous hyphomycetes by dilution plate technique. And then the co-relationship between genus species of soil dematiaceous hyphomycetes and ecosystem-types was analyzed. The results show that the amount and species distribution of soil dematiaceous hyphomycetes had an obvious variability in different ecosystem-types, and that the dominant genus species varied in the eight ecosystem-types studied, with Cladosporium being the dominant genus in seven of the eight ecosystem-types except wetland. The index of species diversity varied in different ecosystem-types. The niche breadth analysis showed that Cladosporium had the highest niche breadth and distributed in all ecosystem-types, while the genera with a narrow niche breadth distributed only in a few ecosystem-types. The results of niche overlap index analysis indicated that Stachybotrys and Torula, Doratomyces and Scolecobasidium, Cladosporium and Chrysosporium had a higher niche overlap, whereas Arthrinium and Gliomastix, Phialophora and Doratomyces, Oidiodendron and Ulocladium had no niche overlap.
基金National Natural Science Foundation of China, No.90202012 National Basic Research Program of China, No.2005CB422006+1 种基金 No.2002CB412507 Knowledge Innovation Project of CAS, No.KZCX3-SW-339
文摘The source region of the Yellow River is located in the middle east of the Tibetan Plateau in northwest China. The total area is about 51,700 km^2, mainly covered by grassland （79%）, unused land （16%） and water （4%）. The increasing land utilization in this area has increased the risk of environmental degradation. The land use/cover data （1985 and 2000） provided by the Data Center of Resources and Environment in the Chinese Academy of Sciences were used to analyze the land cover change in the source region of the Yellow River. DEM （1：250,000） data, roads and settlement data were used to analyze the spatial characteristics of grasslands degradation. The ArcGIS 9 software was used to convert data types and do the overlay, reclassification and zonal statistic analysis. Results show that grassland degradation is the most important land cover change in the study area, which occupied 8.24% of the region＇s total area. Human activities are the main causes of the grassland degradation in the source region of the Yellow River： 1） the degradation rate is higher on the sunny slope than on the shady slope; 2） the grassland degradation rate decreases with an increase in the elevation, and it has a correlation coefficient of -0.93; 3） the nearer to the settlements the grassland is, the higher the degradation rate. Especially within a distance range of 12 km to the settlements, the grassland degradation rate is highly related with the distance, with a coefficient of -0.99; and 4） in the range of 4 km, the degradation rate decreases with the increase of distance to the roads, with a correlation coefficient of -0.98. Besides some physical factors, human activities have been the most important driving forces of the grassland degradation in the source region of the Yellow River since 1985. To resolve the degradation problems, population control is essential, and therefore, it can reduce the social demand of livestock products from the grassland. To achieve sustainable development, it needs to improve the management of grassland ecosystem.
基金Under the auspices of the Major State Basic Research Development Program of China (No. G19990436-01)the Na-tional Natural Science Foundation of China (No. 40471127)
文摘Runoff coefficients of the source regions of the Huanghe River in 1956-2000 were analyzed in this paper. In the 1990s runoff of Tangnaihai Hydrologic Station of the Huanghe River experienced a serious decrease, which had attracted considerable attention. Climate changes have important impact on the water resources availability. From the view of water cycling, runoff coefficients are important indexes of water resources in a particular catchment. Kalinin baseflow separation technique was improved based on the characteristics of precipitation and streamflow. After the separation of runoff coefficient （R/P）, baseflow coefficient （Br/P） and direct runoff coefficient （Dr/P） were estimated. Statistic analyses were applied to assessing the impact of precipitation and temperature on runoff coefficients （including Dr/P, Br/P and R/P）. The results show that in the source regions of the Huanghe River, mean annual baseflow coefficient was higher than mean annual direct runoff coefficient. Annual runoff coefficients were in direct proportion to annual precipitation and in inverse proportion to annual mean temperature. The decrease of runoff coefficients in the 1990s was closely related to the decrease in precipitation and increase in temperature in the same period. Over different sub-basins of the source regions of the Huanghe River, runoff coefficients responded differently to precipitation and temperature. In the area above Jimai Hydrologic Station where annual mean temperature is -3.9℃, temperature is the main factor influencing the runoff coefficients. Runoff coefficients were in inverse relation to temperature, and precipitation had nearly no impact on runoff coefficients. In subbasin between Jimai and Maqu Hydrologic Station Dr/P was mainly affected by precipitation while R/P and Br/P were both significantly influenced by precipitation and temperature. In the area between Maqu and Tangnaihai hydrologic stations all the three runoff coefficients increased with the rising of annual precipitation, while direct runoff coefficient was inversely proportional to temperature. In the source regions of the Huanghe River with the increase of average annual temperature, the impacts of temperature on runoff coefficients become insignificant.
基金the Chinese Academy of Sciences Strategic Priority Research Program(XDA20100103)Ministry of Science and Technology of China Key R&D Program(2017YFC0405704)CAS Overseas Professorships of Victor F Bense and Sergey S Marchenko at the former Cold and Arid Regions Environmental and Engineering Research Institute(now renamed to Northwest Institute of Eco-Environment and Resources),CAS during 2013-2016.
文摘Many observations in and model simulations for northern basins have confirmed an increased streamflow from degrading permafrost,while the streamflow has declined in the source area of the Yellow River(SAYR,above the Tanag hydrological station)on the northeastern Qinghai-Tibet Plateau,West China.How and to what extent does the degrading permafrost change the flow in the SAYR?According to seasonal regimes of hydrological processes,the SAYR is divided intofour sub-basins with varied permafrost extents to detect impacts of permafrost degradation on the Yellow River streamflow.Results show that permafrost degradation may have released appreciable meltwater for recharging groundwater.The potential release rate of ground-ice melt-water in the Sub-basin 1(the headwater area of the Yellow River(HAYR),above the Huangheyan hydrological station)is the highest(5.6 mm per year),contributing to 14.4%of the annual Yellow River streamflow at Huangheyan.Seasonal/intra-and annual shifts of streamflow,a possible signal for the marked alteration of hydrological processes by permafrost degradation,is observed in the HAYR,but the shifts are minor in other sub-basins in the SAYR.Improved hydraulic connectivity is expected to occur during and after certain degrees of permafrost degradation.Direct impacts of permafrost degradation on the annual Yellow River streamflow in the SAYR at Tanag,i.e.,from the meltwater of ground-ice,is estimated at 4.9%that of the annual Yellow River discharge at Tanag,yet with a high uncertainty,due to neglecting of the improved hydraulic connections from permafrost degradation and the flow generation conditions for the ground-ice meltwater.Enhanced evapotranspiration,substantial weakening of the Southwest China Autumn Rain,and anthropogenic disturbances may largely account for the declined streamflow in the SAYR.
基金National Basic Research Program of China,No.2010CB951702International Science & Technology Cooperation Program of China No.2011DFA20820,No.2011DFG93160
文摘There is growing concern over the effects of climate change on glacier melt and hydrology. In this article, we used two natural small-scale basins, Tuotuo River and Buqu River in the source region of the Yangtze River, China, to show the impacts of glacier melt on stream flow. Changes in the extent of glaciers and ice volume in 1970, 1992 and 2009 are evaluated using remote sensing images. Changes to the glacier surface area over the same time interval are estimated through the delineation of glacier outlines and positions using Landsat TM/ETM＋ imagery. By 2009, the glacier surface area had decreased by 20.83% and 34.81% of the 1970 values in Tuotuo River and Baqu River basins respectively. The total meltwater supply in each basin is estimated to be 2.56×10^9 m^3/yr and 1.24×10^9 m^3/yr respectively. Mass balance calculations show that glaciers in the study area suffered a constant mass loss of snow and ice, accumulatively approximately -24 m over the past 40 years. The annual and summer stream flow tended to increase in Tuotuo River basin from 1970 to 2009 while a negative trend of change was shown in Buqu River basin during 1970-1986. Glaciers became shorter, narrower and thinner under the effect of atmospheric warming. Streamflow increase has been recorded at Tuotuo River station in response to increased glacier and permafrost melt. However, streamflow decrease has been recorded at Yanshiping station on Buqu River, where glacier melt has lagged behind atmospheric warming. These results show a close but variable linkage among climate change, glacier melting and water resources in the source region of the Yangtze River.
基金supported by the National Natural Science Foundation of China (41530529,41375022,41575013)the Key Research Program of the Chinese Academy of Sciences (KZZD-EW-13)
文摘Precipitation, a natural feature of weather systems in the Earth, is vitally important for the environment of any region. Under global climate change condition, the characteristics of precipitation have changed as a consequence of enhanced global hydrological cycle. The source region of the Yellow River（SRYR）, locating within the Qinghai-Tibet Plateau, is sensitive to the global climate change due to its complex orography and fragile ecosystem. To understand the precipitation characteristics and its impacts on the environment in the region, we studied the characteristics of rainy days and precipitation amount of different precipitation classes, such as light（0–5 and 5–10 mm）, moderate（10–15, 15–20 and 20–25 mm） and heavy（≥25 mm） rains by analyzing the precipitation data of typical meteorological stations in the SRYR during the period 1961–2014, as well as the trends of persistent rainfall events and drought events. Results showed that annual average precipitation in this area had a non-significant（P〉0.05） increasing trend, and 82.5% of the precipitation occurred from May to September. Rainy days of the 0–5 mm precipitation class significantly decreased, whereas the rainy days of 5–10, 10–15, and 20–25 mm precipitation classes increased and that of ≥25 mm precipitation class decreased insignificantly. The persistent rainfall events of 1-or 2-day and more than 2-day showed an increasing trend, with the 1-or 2-day events being more frequent. Meanwhile, the number of short drought periods（≤10 days） increased while long drought periods（〉10 days） decreased. Since the 0–5 mm precipitation class had a huge impact on the grasslands productivity; the 5–10, 10–15, and 20–25 mm precipitation classes had positive effects on vegetation which rely on the deep soil water through moving nutrients and water into the root zone of these vegetation or through the plant-microbe interactions; the ≥25 mm precipitation class contributed to the floods; and more persistent rainfall events and fewer long drought events inferred positive effects on agriculture. Thus, these results indicate grassland degradation, less risk of floods, and the upgrading impact of climate change on agriculture. This study may provide scientific knowledge for policymakers to sustain the eco-environmental resources in the SYSR.
基金supported by the Major State Basic Research Development Program of China (973 Program) (Grant No. 2007CB411504 and 2007CB411507)the National Natural Science Foundation of China (Grant No. 40771047)
文摘The Yangtze River Source Region has an area of 137,704 km2.Its mean annual runoff of 12.52 billion m3,which was recorded by the Chumda Hydrological Station in 1961–2000,accounts for only 0.13 percent of the Yangtze River's total annual streamflow.The extensive rivers,lakes,wetlands,glaciers,snow fields,and permafrost of the Yangtze River Source Region,as well as the region's vast alpine grasslands,play a critical role in storing and regulating the flow of water not only in the upper Yangtze River watershed of Qinghai,Sichuan,the Tibet Autonomous Region (TAR) (Tibet) and Yunnan,but also throughout the entire lower Yangtze River basin.Climate change has been the dominant factor in recent fluctuation in the volume of the Yangtze River Source Region's glacier resources.The Chumda Hydrological Station on the lower Tongtian River has registered a mean annual glacial meltwater of 1.13 billion m3 for the period 1961–2000,makes up 9 percent of the total annual runoff.Glacial meltwater makes up a significant percentage of streamflow in the Yangtze River Source Region,the major rivers of the upper Yangtze River Source Region:the Togto,Dam Chu,Garchu,and Bi Chu (Bu Chu) rivers all originate at large glaciers along the Tanggula Range.Glaciers in the Yangtze River Source Region are typical continental-type glaciers with most glacial meltwater flow occurring June–August;the close correlation between June–August river flows and temperature illustrates the important role of glacial meltwater in feeding rivers.Glaciers in the source region have undergone a long period of rapid ablation beginning in 1993.Examination of flow and temperature data for the 1961–2000 period shows that the annual melting period for glacial ice,snow,and frozen ground in the Yangtze River Source Region now begins earlier because of increasing spring temperatures,resulting in the reduction of summer flood season peak runoffs;meanwhile,increased rates of glacier ablation have resulted in more uneven annual distribution of runoff in the source region.The annual glacial meltwater runoff in the Yangtze River Source Region is projected to increase by 28.5 percent by 2050 over its 1970 value with the projected temperature increase of 2℃ and a precipitation increase of 29 mm.As a critical source of surface water for agriculture on the eastern Qinghai-Tibet Plateau and beyond,the mass retreat of glaciers in the Yangtze River Source Region will have enormous negative impacts on farming and livestock-raising ac-tivities in upper Yangtze River watershed,as well as on the viability of present ecosystems and even socioeconomic development in the upper Yangtze River Basin.
文摘This study examines the hydrological and meteorological data of the source region of the Yellow River from 1956 to 2010 and future climate scenarios from regional climate model （PRECIS） during 2010-2020. Through analyzing the flow variations and revealing the climate causes, it predicts the variation trend for future flows. It is found that the annual mean flow showed a decreasing trend in recent 50 years in the source region of the Yellow River with quasi-periods of 5a, 8a, 15a, 22a and 42a; the weakened South China Sea summer monsoon induced precipitation decrease, as well as evaporation increase and frozen soil degeneration in the scenario of global warming are the climate factors, which have caused flow decrease. Based on the regional climate model PRECIS prediction, the flows in the source region of the Yellow River are likely to decrease generally in the next 20 years.
基金The Key Deployment Project of the Chinese Academy of Sciences, No.Y322G73001 National Natural Science Foundation of China, No.91225302, No.91437217, No.41375022, No.41175027 Acknowledgments The TRMM data are provided by the NASA/Goddard Space Flight Center＇s Mesoscale Atmospheric Processes Laboratory and PPS, which develop and compute the TMPA as a contribution to TRMM. We acknowledge computing resources and time on the Supercomputing Center of Cold and Arid Region Environment and Engineering Research Institute of Chinese Academy of Sciences. We also acknowledge National Climate Center of China for collecting, analyzing and providing the data of the World Climate Research Programme＇s （WCRP＇s） the Fifth Phase of the Coupled Model Intercomparison Project （CMIP5）.
文摘Climate change investigation at a watershed-scale plays a significant role in re- vealing the historical evolution and future trend of the runoff variation in watershed. This study examines the multisource hydrological and meteorological variables over the source area of the Yellow River （SAYR） from 1961 to 2,012 and the future climate scenarios in the region during 2006-2100 based on the CMIP5 projection data. It recognizes the significant charac-teristics of the recent climate change in the SAYR and predicts the change trend of future flow in the region. It is found that （1） The climate in the SAYR has experienced a significant warm-wet change since the early 2000s, which is very different from the antecedent warm-dry trend since the late 1980s; （2） The warm-wet trend in the northwestern SAYR （the headwater area of the Yellow River （HAYR）, is more obvious than that in the whole SAYR; （3） With pre- cipitation increase, the runoff in the region also experienced an increasing process since 2006. The runoff variations in the region are sensitive to the changes of precipitation, PET and maximum air temperature, but not very sensitive to changes in mean and minimum air temperatures; （4） Based on the CMIP5 projection data, the warm-wet climate trend in SAYR are likely to continue until 2049 if considering three different （i.e. RCP2.6, RCP4.5 and RCP8.5） greenhouse gas emission scenarios, and the precipitation in SAYR will not be less than the current level before 2100; however, it is estimated that the recent flow increase in the SAYR is likely to be the decadal change and it will at most continue until the 2020s; （5） The inter-annual variations of the East Asian winter monsoon are found to be closely related to the variations of annual precipitation in the region. Meanwhile, the increased precipitation as well as the increase of potential evapotranspiration （PET） being far less than that of precipitation in the recent period are the main climate causes for the flow increase in the region.
基金National Key Project for Basic Sciences (973) No. G1999043601
文摘After dividing the source regions of the Yellow River into 38 sub-basins, thepaper made use of the SWAT model to simulate streamflow with validation and calibration of theobserved yearly and monthly runoff data from the Tangnag hydrological station, and simulationresults are satisfactory. Five land-cover scenario models and 24 sets of temperature andprecipitation combinations were established to simulate annual runoff and runoff depth underdifferent scenarios. The simulation shows that with the increasing of vegetation coverage annualrunoff increases and evapotranspiration decreases in the basin. When temperature decreases by 2℃and precipitation increases by 20%, catchment runoff will increase by 39.69%, which is the largestsituation among all scenarios.
基金National Natural Science Foundation of China, No.40405022Special Fund for Social Public Welfare of Research Institutes, No.2005DIB3J109
文摘Taking the source region of the Yellow River as a study area and based on the data from Madoi Meteorological Station and Huangheyan Hydrological Station covering the period 1955-2005, this paper analyses the changing trends of surface water resources, climate and frozen ground and reveals their causes. Results show that there exist frequent fluctuations from high to low water flow in the 51-year period. In general, the discharge has shown a de- clining trend in the 51 years especially since the 1990s. The annual distribution shows one peak which, year on year is getting smaller. （1） Precipitation has a significant and sustained influence on discharge. （2） A sharp rise of temperature resulted in the increase of evaporation and the decrease of discharge, which has a greater effect than on ice-snow melting. （3） Frozen ground tends to be degraded markedly. There is a significant positive correlation be- tween the permafrost thickness and the discharge. （4） Evaporation rates are significantly increasing, leading to the decrease of discharge. 70% of the discharge reduction resulted from climate change, and the remaining 30% may have been caused by human activities.
基金Funding for this research was provided by the National Basic Research Program of China (Grant No. 2010CB 951704)
文摘The interaction among different livelihood capitals is a key to generate a deeper understanding of the livelihood sustainability.In this paper,we use net income per capita(economic capital),meat and milk production per capita(physical capital),and areas of fenced pasture,livestock shelter,grassland rodent control and planted grassland(physical capital) as proxy indicators of livelihood promotion,livelihood provision,and livelihood protection respectively.By developing a correlation model between pastoralists' livelihood protection and improvement,we found that(1) there is a statistically significant correlation between the pastoralists' livelihood protection and promotion;(2) based on the maximum effect of pastoralists' livelihood promotion and provision,there is a benchmark in the effect of the intervention intensity of livelihood capital(grassland resource protection) on livelihood improvement;(3) on basis of two indicators,i.e.net income per capita and meat production per capita,the reasonable scales of fenced pasture,livestock shelter and planted grassland are less than 843,860 and 46 thousand hectares(hm2) per year respectively.With the marginal effect of livelihood protection,moderately decreased areas of fenced pasture and planted grassland,and increased area of livestock shelter is a critical to ensure pastoralist's livelihood sustainability.
