Virtual water trade(VWT)provides a new perspective for alleviating water crisis and has thus attracted widespread attention.However,the heterogeneity of virtual water trade inside and outside the river basin and its i...Virtual water trade(VWT)provides a new perspective for alleviating water crisis and has thus attracted widespread attention.However,the heterogeneity of virtual water trade inside and outside the river basin and its influencing factors remains further study.In this study,for better investigating the pattern and heterogeneity of virtual water trade inside and outside provincial regions along the Yellow River Basin in 2015 using the input-output model(MRIO),we proposed two new concepts,i.e.,virtual water surplus and virtual water deficit,and then used the Logarithmic Mean Divisia Index(LMDI)model to identify the inherent mechanism of the imbalance of virtual water trade between provincial regions along the Yellow River Basin and the other four regions in China.The results show that:1)in provincial regions along the Yellow River Basin,the less developed the economy was,the larger the contribution of the agricultural sector in virtual water trade,while the smaller the contribution of the industrial sector.2)Due to the large output of agricultural products,the upstream and midstream provincial regions of the Yellow River Basin had a virtual water surplus,with a net outflow of virtual water of 2.7×10^(8) m^(3) and 0.9×10^(8) m^(3),respectively.3)provincial regions along the Yellow River Basin were in a virtual water deficit with the rest of China,and the decisive factor was the active degree of trade with the outside.This study would be beneficial to illuminate the trade-related water use issues in provincial regions along the Yellow River Basin,which has farreaching practical signific-ance for alleviating water scarcity.展开更多
The increasing temperature in the Yellow River Basin has led to a rapid rise in the melting level height,at a rate of 5.98 m yr^(-1)during the cold season,which further contributes to the transition from snowfall to r...The increasing temperature in the Yellow River Basin has led to a rapid rise in the melting level height,at a rate of 5.98 m yr^(-1)during the cold season,which further contributes to the transition from snowfall to rainfall patterns.Between 1979 and 2020,there has been a decrease in snowfall in the Yellow River Basin at a rate of-3.03 mm dec^(-1),while rainfall has been increasing at a rate of 1.00 mm dec^(-1).Consequently,the snowfall-to-rainfall ratio(SRR)has decreased.Snowfall directly replenishes terrestrial water storage(TWS)in solid form until it melts,while rainfall is rapidly lost through runoff and evaporation,in addition to infiltrating underground or remaining on the surface.Therefore,the decreasing SRR accelerates the depletion of water resources.According to the surface water balance equation,the reduction in precipitation and runoff,along with an increase in evaporation,results in a decrease in TWS during the cold season within the Yellow River Basin.In addition to climate change,human activities,considering the region's dense population and extensive agricultural land,also accelerate the decline of TWS.Notably,irrigation accounts for the largest proportion of water withdrawals in the Yellow River Basin(71.8%)and primarily occurs during the warm season(especially from June to August).The impact of human activities and climate change on the water cycle requires further in-depth research.展开更多
From the perspective of "human", this study focuses on the feeling of people in a certain region about the waterfront environment, by combining with theories in landscape architecture, environmental psycholo...From the perspective of "human", this study focuses on the feeling of people in a certain region about the waterfront environment, by combining with theories in landscape architecture, environmental psychology and other interdisciplines, in view of present situation of waterfront landscapes in the Yellow River Scenic Area of Zhengzhou City, tries to find new approaches for waterfront landscape design and development based on landscape design principles and exploration of the human's nature of loving water and the interaction between tourists and waterfront landscapes.展开更多
Natural radionuclides are powerful tools for understanding the sources and fate of suspended particulate matter(SPM).Particulate matter with different particle sizes behaves differently with respect to adsorption and ...Natural radionuclides are powerful tools for understanding the sources and fate of suspended particulate matter(SPM).Particulate matter with different particle sizes behaves differently with respect to adsorption and desorption.We analyzed the activi-ties and distribution characteristics of multiple natural radionuclides(238U,226Ra,40K,228Ra,7Be and 210Pbex)on size-fractionated SPM at the Lijin Hydrographic Station(Huanghe or Yellow River)every month over a one-year period.Results showed that medium silt(16–32µm)was the main component.As expected,the activity of each radionuclide decreased with an increase of particle size.We examined the sources of SPM with different particle sizes using activity ratios of 226Ra/238U,228Ra/226Ra,40K/238U and 7Be/210Pbex,and concluded that SPM with different particle sizes originated from different sources.Our results indicate that fine SPM(<32µm)was mainly from the erosion of soil along the lower reaches of the Yellow River,while coarse SPM(>32µm)was mainly derived from resuspension of riverbed sediment.During high runoff periods,the concentration of SPM increased significantly,and the pro-portion of fine particles originating upstream increased.Naturally occurring radioactive isotopes,especially on size-fractionated par-ticles,are therefore seen as useful tracers to understand the sources and behaviors of riverine particles transported from land to sea.展开更多
In order to find out the variation process of water-sediment and its effect on the Yellow River Delta, the water discharge and sediment load at Lijin from 1950 to 2007 and the decrease of water discharge and sediment ...In order to find out the variation process of water-sediment and its effect on the Yellow River Delta, the water discharge and sediment load at Lijin from 1950 to 2007 and the decrease of water discharge and sediment load in the Yellow River Basin caused by human disturbances were analyzed by means of statistics. It was shown that the water discharge and sediment load into the sea were decreasing from 1950 to 2007 with serious fluctuation. The human activities were the main cause for decrease of water discharge and sediment load into the sea. From 1950 to 2005, the average annual reduction of water discharge and sediment load by means of water-soil conservation practices were 2.02×10^9 m^3 and 3.41×10^8 t respectively, and the average annual volume by water abstraction for industry and agriculture were 2.52×10^10 m^3 and 2.42×10^8 t respectively. The average sediment trapped by Sanmenxia Reservoir was 1.45×10^8 t from 1960 to 2007, and the average sediment retention of Xiaolangdi Reservoir was 2.398×10^8t from 1997 to 2007. Compared to the data records at Huanyuankou, the water discharge and sediment load into the sea decreased with siltation in the lower reaches and increased with scouring in the lower reaches. The coastline near river mouth extended and the delta area increased when the ratio of accumulative sediment load and accumulative water discharge into the sea (SSCT) is 25.4-26.0 kg/m^3 in different time periods. However, the sharp decrease of water discharge and sediment load into the sea in recent years, especially the Yellow River into the sea at Qing 8, the entire Yellow River Delta has turned into erosion from siltation, and the time for a reversal of the state was about 1997.展开更多
In order to realistically reflect the difference between regional water demand for instream flow and river ecological water demand as well as to resolve the problem that water demand may be counted repeatedly, a conce...In order to realistically reflect the difference between regional water demand for instream flow and river ecological water demand as well as to resolve the problem that water demand may be counted repeatedly, a concept of regional water demand for minimum instream flow have been developed. The concept was used in the process of determining river functions and calculating ecological water demand for a river. The Yellow River watershed was used to validate the calculation methodology for regional water demand. CaIculation results indicate that there are significant differences in water demands among the different regions. The regional water demand at the downstream of the Yellow River is the largest about 14.893 × 10^9 m^3/a. The regional water demand of upstream, Lanzhou-Hekou section is the smallest about -5.012 × 10^9 m^3/a. The total ecological water demand of the Yellow River Basin is 23.06 × 10^9 m^3/a, about the 39% of surface water resources of the water resources should not exceed 61% in the Yellow River Basin. Yellow River Basin. That means the maximum available surface The regional river ecological water demands at the Lower Section of the Yellow River and Longyangxia-Lanzhou Section exceed the surface water resources produced in its region and need to be supplemented from other regions through the water rational planning of watershed water resources. These results provides technical basis for rational plan of water resources of the Yellow River Basin.展开更多
Water storage has important significance for understanding water cycles of global and local domains and for monitoring climate and environmental changes. As a key variable in hydrology, water storage change represents...Water storage has important significance for understanding water cycles of global and local domains and for monitoring climate and environmental changes. As a key variable in hydrology, water storage change represents the sum of precipitation, evaporation, surface runoff, soil water and groundwater exchanges. Water storage change data during the period of 2003-2008 for the source region of the Yellow River were collected from Gravity Recovery and Climate Experiment (GRACE) satellite data. The monthly actual evaporation was estimated according to the water balance equation. The simulated actual evaporation was significantly consistent and correlative with not only the observed pan (20 cm) data, but also the simulated results of the version 2 of Simple Biosphere model. The average annual evaporation of the Tangnaihai Basin was 506.4 mm, where evaporation in spring, summer, autumn and winter was 130.9 mm, 275.2 mm, 74.3 mm and 26.1 mm, and accounted for 25.8%, 54.3%, 14.7% and 5.2% of the average annual evaporation, respectively, The precipitation increased slightly and the actual evaporation showed an obvious decrease. The water storage change of the source region of the Yellow River displayed an increase of 0.51 mm per month from 2003 to 2008, which indicated that the storage capacity has significantly increased, probably caused by the degradation of permafrost and the increase of the thickness of active layers. The decline of actual evaporation and the increase of water storage capacity resulted in the increase of river runoff.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 chemical and isotopic characteristics of the water and suspended particulate materials (SPM) in the Yellow River were investigated on the samples collected from 29 hydrological monitoring stations in the mainste...The chemical and isotopic characteristics of the water and suspended particulate materials (SPM) in the Yellow River were investigated on the samples collected from 29 hydrological monitoring stations in the mainstem and several major tributaries during 2004 to 2007. The JD and δ^18O values of the Yellow River water vary in large ranges from -32%0 to -91‰ and from -3.1‰ to -12.5‰, respectively. The characters of H and O isotope variations indicate that the major sources of the Yellow River water are meteoric water and snow melting water, and water cycle in the Yellow River basin is affected strongly by evaporation process and human activity. The average SPM content (9.635 g/L) of the Yellow River is the highest among the world large rivers. Compared with the Yangtze River, the Yellow River SPM has much lower clay content and significantly higher contents of clastic silicates and carbonates. In comparison to the upper crust rocks, the Yellow River SPM contains less SiO2, CaO, K2O and Na2O, but more TFe203, Co, Ni, Cu, Zn, Pb and Cd. The abnormal high Cd contents found in some sample may be related to local industrial activity. The REE contents and distribution pattern of the Yellow River SPM are very close to the average value of the global shale. The average δ^30Sisp in the Yellow River (-0.11‰) is slightly higher than the average value (-0.22‰) of the Yangtze River SPM. The major factors controlling the δ^30Si SPM of the Yellow River are the soil supply, the isotopic composition of the soil and the climate conditions. The TDS in the Yellow River are the highest among those of world large rivers. Fair correlations are observed among Cl, Na^+, K^+, and Mg^2+ contents of the Yellow River water, indicating the effect of evaporation. The Ca^2+ and Sr^2+ concentrations show good correlation to the SO42 concentration rather than HCO3-concentration, reflecting its origin from evaporates. The NO3-contents are affected by farmland fertilization. The Cu, Zn and Cd contents in dissolved load of the Yellow River water are all higher than those of average world large rivers, reflecting the effect of human activity. The dissolved load in the Yellow River water generally shows a REE distribution pattern parallel to those for the Yangtze River and the Xijiang River. The δ^30Si values of the dissolved silicon vary in a range from 0.4%0 to 2.9%0, averaging 1.34%o. The major processes controlling the Dsi weathering process of silicate rocks, growth of and δ^30SiDiss of the Yellow River water are the phytolith in plants, evaporation, dissolution of phytolith in soil, growth of fresh water diatom, adsorption and desorption of aqueous monosilicic acid on iron oxide and human activities. The average δ^30^SiDiss value of the Yellow River is significantly lower than that of the Nile River, Yangtze River and Siberia rivers, but higher than those of other rivers, reflecting their differences in chemical weathering and biological activity. The δ^34SSO4 values of the Yellow River water range from -3.8%0 to 14.1%o, averaging 7.97%0. There is some correlation between SO4^2- content and δ^34SSO4. The factors controlling the δ^34SSO4 of the Yellow River water are the SO4 in the meteoric water, the SO4 from gypsum or anhydrite in evaporite rocks, oxidation and dissolution of sulfides in the mineral deposits, magmatic rocks and sedimentary rocks, the sulfate reduction and precipitation process and the sulfate from fertilizer. The ^87Sr/^86Sr ratios of all samples range from 0.71041 to 0.71237, averaging 0.71128. The variations in the ^87Sr/^86Sr ratio and Sr concentration of river water are primarily caused by mixing of waters of various origins with different 87Sr/S6Sr ratios and Sr contents resulting from water-rock interaction with different rock types.展开更多
Since 2002, an artificial water and sediment regulation(AWSR) has been carried out, which largely reduced water and sediment discharged from the Yellow River into the Bohai Sea. Although the sediment transport in the ...Since 2002, an artificial water and sediment regulation(AWSR) has been carried out, which largely reduced water and sediment discharged from the Yellow River into the Bohai Sea. Although the sediment transport in the Yellow River Mouth(YRM) has been observed and modeled intensively since AWSR, but preferentially for the non-storm conditions. In this study, a three-dimensional current-wave-sediment coupled model, DHI-MIKE numerical model, was used to examine the seasonal suspended-sediment transport in the YRM after the AWSR. Results show that the seasonal distribution of suspended-sediments in the YRM is dominated by wind and wave rather than river input. The major transport pathway of suspended-sediments is from the western Laizhou Bay to the Bohai Strait during the winter monsoon, especially in storm events. In addition, about 66% of the river sediments deposit within 30 km of the YRM, which is smaller than previous estimations. It suggests that the YRM has been eroded in recent decades.展开更多
The well-documented decrease in the discharge of sediment into the Yellow River has attracted considerable attention in recent years. The present study analyzed the spatial and temporal variation of sediment yield bas...The well-documented decrease in the discharge of sediment into the Yellow River has attracted considerable attention in recent years. The present study analyzed the spatial and temporal variation of sediment yield based on data from 46 hydrological stations in the sediment-rich region of the Yellow River from 1955 to 2010. The results showed that since 1970 sediment yield in the region has clearly decreased at different rates in the 45 sub-areas controlled by hydrological stations. The decrease in sediment yield was closely related to the intensity and extent of soil erosion control measures and rainstorms that occurred in different periods and sub-areas. The average sediment delivery modulus(SDM) in the study area decreased from 7,767.4 t/(km^2·a) in 1951–1969 to 980.5 t/(km^2·a) in 2000–2010. Our study suggested that 65.5% of the study area with the SDM below 1,000 t/(km^2·a) is still necessary to control soil deterioration caused by erosion, and soil erosion control measures should be further strengthened in the areas with the SDM above 1,000 t/(km^2·a).展开更多
As critical component of hydrologic cycle, basin discharge is a key issue for understanding the hydrological and climatologic related to water and energy cycles. Combining GRACE gravity field models with ET from GLDAS...As critical component of hydrologic cycle, basin discharge is a key issue for understanding the hydrological and climatologic related to water and energy cycles. Combining GRACE gravity field models with ET from GLDAS models and precipitation from GPCP, discharge of the Yellow River basin are estimated from the water balance equation. While comparing the results with discharge from GLDAS model and in situ measurements, the results reveal that discharge from Mosaic and CLM GLDAS model can partially represent the river discharge and the discharge estimation from water balance equation could reflect the discharge from precipitation over the Yellow River basin.展开更多
A large number of antibiotics have been discharged into rivers by human activities,posing a threat to aquatic ecosystems.The surface water of the Yellow River Basin also suffers antibiotic pollution,which hinders the ...A large number of antibiotics have been discharged into rivers by human activities,posing a threat to aquatic ecosystems.The surface water of the Yellow River Basin also suffers antibiotic pollution,which hinders the improvement in the aquatic ecological environment.This study investigated and analyzed the characteristics and assessed the ecological risks of antibiotic pollution in surface water bodies such as canals,rivers and fish ponds in Kaifeng,Henan Province,which is a key city along the lower reaches of the Yellow River.The test results are as follows.A total of 15 types of antibiotics were detected in the surface water.They had a total antibiotic concentration of 12.2-249.9μg/L,of which tetracyclines(TCs)and quinolones accounted for the highest percentages.Six types of quinolones had detection rates of up to 100%,and doxycycline(DC)and oxytetracycline(OTC)had average concentrations of 29.52μg/L1 and 13.71μg/L,respectively.The major canals with water diverted from the Yellow River had total concentrations of quinolones and TCs of 22.0μg/L and 14.9μg/L,respectively,which were higher than those in previous studies.This phenomenon may be related to the decrease in the water flow of the Yellow River during the dry season and the increase in the antibiotic consumption of residents in the context of the Covid-19 outbreak.The upper reaches of the Huiji River in the Xiangfu District had higher antibiotic content than other districts in Kaifeng.Specifically,TCs accounted for 72.38%-91.84%of all antibiotics,and the DC and OTC concentrations were significantly higher than other antibiotics in the upper reaches.As indicated by the ecological risk assessment results,TCs had the highest ecological risks to green algae.Among them,DC had medium-high risks;TC,OTC,and chlortetracycline(CTC)had medium-high risks;trimethoprim(TMP)and lomefloxacin(LOM)had low risks;other TC antibiotics had no risk.Compared with green algae,most antibiotics showed higher ecological risks to daphnia and lower ecological risks to fish.DC and OTC dominate antibiotic pollutants in the surface water in Kaifeng City,and especially in Xiangfu District,where DC and OTC have medium-high risks.The TCs in the major Yellow River showed medium risks to both green algae and daphnia.It can be speculated that the antibiotic pollution in the Yellow River might pose a certain threat to the ecological security of water in Kaifeng City.展开更多
Since the 1990s, the Yellow River stream has been temporarily interrupted for several years, which affects the development of society, the economy and human life, limits the economic potential of the drainage areas, a...Since the 1990s, the Yellow River stream has been temporarily interrupted for several years, which affects the development of society, the economy and human life, limits the economic potential of the drainage areas, and especially causes great harm to regions on the lower reaches. Based on the analysis of the relationship between the development of society and economy and water scarcity, the author thinks it is necessary to optimize and adjust the industrial structure that has extravagantly consumed enormous amounts of water, and to develop ecological agriculture, industry and tourism which are balanced with the ecological environment. Finally, the author puts forward several pieces of advice and countermeasures about how to build the economic systems by which water can be used economically.展开更多
To determine the pollution levels and potential toxic risks of arsenic(As) and heavy metals(Cr, Ni, Cu, Zn, Pb and Cd) in water and suspended particulate matter(SPM) in tail reaches(including freshwater reach and low-...To determine the pollution levels and potential toxic risks of arsenic(As) and heavy metals(Cr, Ni, Cu, Zn, Pb and Cd) in water and suspended particulate matter(SPM) in tail reaches(including freshwater reach and low-salinity reach) of the Yellow River as the Flow-Sediment Regulation Project(FSRP) has been carried out for approximately 15 yr, the surface water and SPM were sampled at pre-flood(April) and post-flood seasons(October). Results showed that similar changes of As and metal levels in water and SPM were observed along the tail reaches at pre-flood or post-flood season. Compared to pre-flood season, the levels of As, Cu, Cr and Ni in freshwater reach and the concentrations of Cr and Ni in low-salinity reach rose greatly at post-flood season. The levels of As and metals in SPM of freshwater reach or low-salinity reach at pre-flood season were significantly higher than those at post-flood season(P < 0.01).The pollutions of As and metals in surface water of tail reaches at pre-flood or post-flood season were not serious. The SPM in freshwater reach at pre-flood season were polluted by Cd, As, Cr, Cu and Ni while those in low-salinity reach were polluted by Cd and Cr. The SPM in freshwater reach at post-flood season were polluted by Cd and Pb while those in low-salinity reach were polluted by Cd and Cr.Cd was identified as heavy metal of primary concern at both pre-flood and post-flood seasons. Combined with the existed data reported in present research, this study found that the toxic risk of As and metals in SPM of tail reaches at pre-flood season was higher than that at post-flood season, implying that the implementation of FSRP during flooding season, to a great extent, reduced the toxic risk of these elements. With the long-term implementation of FSRP, the pollution levels of As and metals(particularly for Cd) in SPM of tail reaches might be elevated and the potential toxic risk primarily produced by Cr, Ni and As might be increased if effective measures were not taken in future.展开更多
Based on the isotope analysis result of water samples in the 18 sections of the Yellow River, the variation of δ 18 O and δD have been analyzed. From near the source to the entrance to the sea, the Yellow River has ...Based on the isotope analysis result of water samples in the 18 sections of the Yellow River, the variation of δ 18 O and δD have been analyzed. From near the source to the entrance to the sea, the Yellow River has a general trend that the ratios of the stable isotope increase progressively; The main factors affecting the isotopes in the river water are mixing of external water bodies,evaporation and others; In the river segment between Lanzhou and Baotou and in lower reaches, the extent of the evaporation effect on the isotope fractionation from the river water surface is limited but the evaporation from the irrigated river water and the return flow is one of the main factors affecting the isotopes in river water.展开更多
In order to examine the impacts of water-sediment regulation on regional carbon cycling,we collected water,particulate and sediment samples from the middle-lower Yellow River in late June and early July,2015 and analy...In order to examine the impacts of water-sediment regulation on regional carbon cycling,we collected water,particulate and sediment samples from the middle-lower Yellow River in late June and early July,2015 and analyzed their specific amino acids(AA),DOC,POC,and bacteria abundance.Summarized by 14 specific AA,the total hydrolysable AA(THAA),particulate AA(PAA),and sediment AA(SAA)varied in ranges of 2.29-9.05μmol L^-1,5.22-22.96μmol L^-1,and 81.7-137.19μg g^-1 dry weight.After the regulation,dissolved free AA(DFAA)decreased by 29%while DCAA increased by 72%.These variations suggested that DFAA were further degraded,while DCAA molecules were further activated.Meanwhile,PAA increased almost 4 times as many as those before regulation,and SAA increased as well.After regulation,the amounts of bioactive amino acids(Asp,Glu and Gly)increased in THAA but decreased in PAA,with little changes in SAA.The ratios of Asp/Gly in different phases increased after regulation,indicating the AA contributions were promoted by calcareous organisms rather than by siliceous organisms.Multiple correlation analysis showed that PAA was primary representatives of AA and organic carbon,followed by DCAA and POC.Moreover,bacterial reproduction played a key role in shaping the AA compositions and properties,followed by the redox condition and acid-base balance.The results of this study provided a clear evidence for the effects of water-sediment regulation on regional biogeochemistry of organic carbon in the middle-lower Yellow River.展开更多
The paper describes the water resources in the irrigated area of Ningxia, China, andthe methods for improving the utilization of the water resources, and puts forward somesuggestions so as to utilize the water resourc...The paper describes the water resources in the irrigated area of Ningxia, China, andthe methods for improving the utilization of the water resources, and puts forward somesuggestions so as to utilize the water resources rationally. The history of irrigation farming in Ningxia can be traced back to more than two thou-展开更多
An underlying wetland surface comprises soil, water and vegetation and is sensitive to local climate change. Analysis of the degree of coupling between wetlands and the atmosphere and a quantitative assessment of how ...An underlying wetland surface comprises soil, water and vegetation and is sensitive to local climate change. Analysis of the degree of coupling between wetlands and the atmosphere and a quantitative assessment of how environmental factors influence latent heat flux have considerable scientific significance. Using data from observational tests of the Maduo Observatory of Climate and Environment of the Northwest Institute of Eco-Environment and Resource, CAS, from June 1 to August 31, 2014, this study analysed the time-varying characteristics and causes of the degree of coupling(Ω factor)between alpine wetlands underlying surface and the atmosphere and quantitatively calculated the influences of different environmental factors(solar radiation and vapour pressure deficit) on latent heat flux. The results were as follows:(1) Due to diurnal variations of solar radiation and wind speed, a trend developed where diurnal variations of the Ω factor were small in the morning and large in the evening. Due to the vegetation growing cycle, seasonal variations of the Ω factor present a reverse "U" trend. These trends are similar to the diurnal and seasonal variations of the absolute control exercised by solar radiation over latent heat flux. This conforms to the Omega Theory.(2) The values for average absolute atmospheric factor(surface factor or total) control exercised by solar radiation and water vapour pressure are 0.20(0.02 or 0.22) and 0.005(-0.07 or-0.06) W/(m2·Pa), respectively. Generally speaking, solar radiation and water vapour pressure deficit exert opposite forces on latent heat flux.(3) At the underlying alpine wetland surface, solar radiation primarily influences latent heat flux through its direct effects(atmospheric factor controls). Water vapour pressure deficit primarily influences latent heat flux through its indirect effects(surface factor controls) on changing the surface resistance.(4) The average Ω factor in the underlying alpine wetland surface is high during the vegetation growing season, with a value of 0.38, and the degree of coupling between alpine wetland surface and atmosphere system is low. The actual measurements agree with the Omega Theory. The latent heat flux is mainly influenced by solar radiation.展开更多
The issue on water environmental degradation in the source area of the Yellow River has been one of very serious ecological and socially economic problems. The temporal-spatial changes of water environment led to the ...The issue on water environmental degradation in the source area of the Yellow River has been one of very serious ecological and socially economic problems. The temporal-spatial changes of water environment led to the decreasing of land capacity and river disconnecting. The status of water environmental degradation in this paper was analyzed based on the data and field investigation. The results indicated that the surface water area in the region has obviously decreased owing to the climate changes and human irrational use of water resources and the continuous lowering of the regional groundwater table and the steadily decreasing tendency of the flow rate in the source areas of the Yellow River.展开更多
基金Under the auspices of National Natural Science Foundation of China(No.42201302)‘Double First-Class’University Construction Project of Lanzhou University(No.561120213)。
文摘Virtual water trade(VWT)provides a new perspective for alleviating water crisis and has thus attracted widespread attention.However,the heterogeneity of virtual water trade inside and outside the river basin and its influencing factors remains further study.In this study,for better investigating the pattern and heterogeneity of virtual water trade inside and outside provincial regions along the Yellow River Basin in 2015 using the input-output model(MRIO),we proposed two new concepts,i.e.,virtual water surplus and virtual water deficit,and then used the Logarithmic Mean Divisia Index(LMDI)model to identify the inherent mechanism of the imbalance of virtual water trade between provincial regions along the Yellow River Basin and the other four regions in China.The results show that:1)in provincial regions along the Yellow River Basin,the less developed the economy was,the larger the contribution of the agricultural sector in virtual water trade,while the smaller the contribution of the industrial sector.2)Due to the large output of agricultural products,the upstream and midstream provincial regions of the Yellow River Basin had a virtual water surplus,with a net outflow of virtual water of 2.7×10^(8) m^(3) and 0.9×10^(8) m^(3),respectively.3)provincial regions along the Yellow River Basin were in a virtual water deficit with the rest of China,and the decisive factor was the active degree of trade with the outside.This study would be beneficial to illuminate the trade-related water use issues in provincial regions along the Yellow River Basin,which has farreaching practical signific-ance for alleviating water scarcity.
基金National Natural Science Foundation of China (42041004)。
文摘The increasing temperature in the Yellow River Basin has led to a rapid rise in the melting level height,at a rate of 5.98 m yr^(-1)during the cold season,which further contributes to the transition from snowfall to rainfall patterns.Between 1979 and 2020,there has been a decrease in snowfall in the Yellow River Basin at a rate of-3.03 mm dec^(-1),while rainfall has been increasing at a rate of 1.00 mm dec^(-1).Consequently,the snowfall-to-rainfall ratio(SRR)has decreased.Snowfall directly replenishes terrestrial water storage(TWS)in solid form until it melts,while rainfall is rapidly lost through runoff and evaporation,in addition to infiltrating underground or remaining on the surface.Therefore,the decreasing SRR accelerates the depletion of water resources.According to the surface water balance equation,the reduction in precipitation and runoff,along with an increase in evaporation,results in a decrease in TWS during the cold season within the Yellow River Basin.In addition to climate change,human activities,considering the region's dense population and extensive agricultural land,also accelerate the decline of TWS.Notably,irrigation accounts for the largest proportion of water withdrawals in the Yellow River Basin(71.8%)and primarily occurs during the warm season(especially from June to August).The impact of human activities and climate change on the water cycle requires further in-depth research.
文摘From the perspective of "human", this study focuses on the feeling of people in a certain region about the waterfront environment, by combining with theories in landscape architecture, environmental psychology and other interdisciplines, in view of present situation of waterfront landscapes in the Yellow River Scenic Area of Zhengzhou City, tries to find new approaches for waterfront landscape design and development based on landscape design principles and exploration of the human's nature of loving water and the interaction between tourists and waterfront landscapes.
基金financially supported by the National Natural Science Foundation of China(Nos.U22A20580,42130410,and U1906210)the Fundamental Research Funds for the Central Universities(No.201962003).
文摘Natural radionuclides are powerful tools for understanding the sources and fate of suspended particulate matter(SPM).Particulate matter with different particle sizes behaves differently with respect to adsorption and desorption.We analyzed the activi-ties and distribution characteristics of multiple natural radionuclides(238U,226Ra,40K,228Ra,7Be and 210Pbex)on size-fractionated SPM at the Lijin Hydrographic Station(Huanghe or Yellow River)every month over a one-year period.Results showed that medium silt(16–32µm)was the main component.As expected,the activity of each radionuclide decreased with an increase of particle size.We examined the sources of SPM with different particle sizes using activity ratios of 226Ra/238U,228Ra/226Ra,40K/238U and 7Be/210Pbex,and concluded that SPM with different particle sizes originated from different sources.Our results indicate that fine SPM(<32µm)was mainly from the erosion of soil along the lower reaches of the Yellow River,while coarse SPM(>32µm)was mainly derived from resuspension of riverbed sediment.During high runoff periods,the concentration of SPM increased significantly,and the pro-portion of fine particles originating upstream increased.Naturally occurring radioactive isotopes,especially on size-fractionated par-ticles,are therefore seen as useful tracers to understand the sources and behaviors of riverine particles transported from land to sea.
基金Special Expenses Program of Scientific Research in Marine Commonweal Industry, No.200805063Scien-tific Research Program of State Key Laboratory of Estuarine and Coastal Research, No.2008KYYW06Open-end Foundation of State Oceanic Administration Key Laboratory of Marine Sedimentology & Envi-ronmental Geology, No.MASEG200608
文摘In order to find out the variation process of water-sediment and its effect on the Yellow River Delta, the water discharge and sediment load at Lijin from 1950 to 2007 and the decrease of water discharge and sediment load in the Yellow River Basin caused by human disturbances were analyzed by means of statistics. It was shown that the water discharge and sediment load into the sea were decreasing from 1950 to 2007 with serious fluctuation. The human activities were the main cause for decrease of water discharge and sediment load into the sea. From 1950 to 2005, the average annual reduction of water discharge and sediment load by means of water-soil conservation practices were 2.02×10^9 m^3 and 3.41×10^8 t respectively, and the average annual volume by water abstraction for industry and agriculture were 2.52×10^10 m^3 and 2.42×10^8 t respectively. The average sediment trapped by Sanmenxia Reservoir was 1.45×10^8 t from 1960 to 2007, and the average sediment retention of Xiaolangdi Reservoir was 2.398×10^8t from 1997 to 2007. Compared to the data records at Huanyuankou, the water discharge and sediment load into the sea decreased with siltation in the lower reaches and increased with scouring in the lower reaches. The coastline near river mouth extended and the delta area increased when the ratio of accumulative sediment load and accumulative water discharge into the sea (SSCT) is 25.4-26.0 kg/m^3 in different time periods. However, the sharp decrease of water discharge and sediment load into the sea in recent years, especially the Yellow River into the sea at Qing 8, the entire Yellow River Delta has turned into erosion from siltation, and the time for a reversal of the state was about 1997.
基金The National Natural Sciences Foundation of China (No. 50239020)
文摘In order to realistically reflect the difference between regional water demand for instream flow and river ecological water demand as well as to resolve the problem that water demand may be counted repeatedly, a concept of regional water demand for minimum instream flow have been developed. The concept was used in the process of determining river functions and calculating ecological water demand for a river. The Yellow River watershed was used to validate the calculation methodology for regional water demand. CaIculation results indicate that there are significant differences in water demands among the different regions. The regional water demand at the downstream of the Yellow River is the largest about 14.893 × 10^9 m^3/a. The regional water demand of upstream, Lanzhou-Hekou section is the smallest about -5.012 × 10^9 m^3/a. The total ecological water demand of the Yellow River Basin is 23.06 × 10^9 m^3/a, about the 39% of surface water resources of the water resources should not exceed 61% in the Yellow River Basin. Yellow River Basin. That means the maximum available surface The regional river ecological water demands at the Lower Section of the Yellow River and Longyangxia-Lanzhou Section exceed the surface water resources produced in its region and need to be supplemented from other regions through the water rational planning of watershed water resources. These results provides technical basis for rational plan of water resources of the Yellow River Basin.
基金funded by the Global Change Research Program of China (2010CB951401)the National Natural Science Foundation of China (41030638, 41121001, 41030527,41130641,and 41201025)the One Hundred Talents Program of the Chinese Academy of Sciences
文摘Water storage has important significance for understanding water cycles of global and local domains and for monitoring climate and environmental changes. As a key variable in hydrology, water storage change represents the sum of precipitation, evaporation, surface runoff, soil water and groundwater exchanges. Water storage change data during the period of 2003-2008 for the source region of the Yellow River were collected from Gravity Recovery and Climate Experiment (GRACE) satellite data. The monthly actual evaporation was estimated according to the water balance equation. The simulated actual evaporation was significantly consistent and correlative with not only the observed pan (20 cm) data, but also the simulated results of the version 2 of Simple Biosphere model. The average annual evaporation of the Tangnaihai Basin was 506.4 mm, where evaporation in spring, summer, autumn and winter was 130.9 mm, 275.2 mm, 74.3 mm and 26.1 mm, and accounted for 25.8%, 54.3%, 14.7% and 5.2% of the average annual evaporation, respectively, The precipitation increased slightly and the actual evaporation showed an obvious decrease. The water storage change of the source region of the Yellow River displayed an increase of 0.51 mm per month from 2003 to 2008, which indicated that the storage capacity has significantly increased, probably caused by the degradation of permafrost and the increase of the thickness of active layers. The decline of actual evaporation and the increase of water storage capacity resulted in the increase of river runoff.
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supported by the National Natural Science Foundation of China(Item No.40673005)the Ministry of Science and Technology(Item No. 2004DIB3J081)the Geological Survey of China(Item No.200320130-006)
文摘The chemical and isotopic characteristics of the water and suspended particulate materials (SPM) in the Yellow River were investigated on the samples collected from 29 hydrological monitoring stations in the mainstem and several major tributaries during 2004 to 2007. The JD and δ^18O values of the Yellow River water vary in large ranges from -32%0 to -91‰ and from -3.1‰ to -12.5‰, respectively. The characters of H and O isotope variations indicate that the major sources of the Yellow River water are meteoric water and snow melting water, and water cycle in the Yellow River basin is affected strongly by evaporation process and human activity. The average SPM content (9.635 g/L) of the Yellow River is the highest among the world large rivers. Compared with the Yangtze River, the Yellow River SPM has much lower clay content and significantly higher contents of clastic silicates and carbonates. In comparison to the upper crust rocks, the Yellow River SPM contains less SiO2, CaO, K2O and Na2O, but more TFe203, Co, Ni, Cu, Zn, Pb and Cd. The abnormal high Cd contents found in some sample may be related to local industrial activity. The REE contents and distribution pattern of the Yellow River SPM are very close to the average value of the global shale. The average δ^30Sisp in the Yellow River (-0.11‰) is slightly higher than the average value (-0.22‰) of the Yangtze River SPM. The major factors controlling the δ^30Si SPM of the Yellow River are the soil supply, the isotopic composition of the soil and the climate conditions. The TDS in the Yellow River are the highest among those of world large rivers. Fair correlations are observed among Cl, Na^+, K^+, and Mg^2+ contents of the Yellow River water, indicating the effect of evaporation. The Ca^2+ and Sr^2+ concentrations show good correlation to the SO42 concentration rather than HCO3-concentration, reflecting its origin from evaporates. The NO3-contents are affected by farmland fertilization. The Cu, Zn and Cd contents in dissolved load of the Yellow River water are all higher than those of average world large rivers, reflecting the effect of human activity. The dissolved load in the Yellow River water generally shows a REE distribution pattern parallel to those for the Yangtze River and the Xijiang River. The δ^30Si values of the dissolved silicon vary in a range from 0.4%0 to 2.9%0, averaging 1.34%o. The major processes controlling the Dsi weathering process of silicate rocks, growth of and δ^30SiDiss of the Yellow River water are the phytolith in plants, evaporation, dissolution of phytolith in soil, growth of fresh water diatom, adsorption and desorption of aqueous monosilicic acid on iron oxide and human activities. The average δ^30^SiDiss value of the Yellow River is significantly lower than that of the Nile River, Yangtze River and Siberia rivers, but higher than those of other rivers, reflecting their differences in chemical weathering and biological activity. The δ^34SSO4 values of the Yellow River water range from -3.8%0 to 14.1%o, averaging 7.97%0. There is some correlation between SO4^2- content and δ^34SSO4. The factors controlling the δ^34SSO4 of the Yellow River water are the SO4 in the meteoric water, the SO4 from gypsum or anhydrite in evaporite rocks, oxidation and dissolution of sulfides in the mineral deposits, magmatic rocks and sedimentary rocks, the sulfate reduction and precipitation process and the sulfate from fertilizer. The ^87Sr/^86Sr ratios of all samples range from 0.71041 to 0.71237, averaging 0.71128. The variations in the ^87Sr/^86Sr ratio and Sr concentration of river water are primarily caused by mixing of waters of various origins with different 87Sr/S6Sr ratios and Sr contents resulting from water-rock interaction with different rock types.
基金supported by the National Natural Science Foundation of China (Nos. 41476030, U1706215, and 41406081)the Project of Taishan Scholar
文摘Since 2002, an artificial water and sediment regulation(AWSR) has been carried out, which largely reduced water and sediment discharged from the Yellow River into the Bohai Sea. Although the sediment transport in the Yellow River Mouth(YRM) has been observed and modeled intensively since AWSR, but preferentially for the non-storm conditions. In this study, a three-dimensional current-wave-sediment coupled model, DHI-MIKE numerical model, was used to examine the seasonal suspended-sediment transport in the YRM after the AWSR. Results show that the seasonal distribution of suspended-sediments in the YRM is dominated by wind and wave rather than river input. The major transport pathway of suspended-sediments is from the western Laizhou Bay to the Bohai Strait during the winter monsoon, especially in storm events. In addition, about 66% of the river sediments deposit within 30 km of the YRM, which is smaller than previous estimations. It suggests that the YRM has been eroded in recent decades.
基金funded by the Major Programs of the Chinese Academy of Sciences (KZZD-EW-04-03-04)the National Science-technology Support Plan Project (2006BAD09B10)the Knowledge Innovation Program of the Chinese Academy of Sciences (KZCX2-EW-406)
文摘The well-documented decrease in the discharge of sediment into the Yellow River has attracted considerable attention in recent years. The present study analyzed the spatial and temporal variation of sediment yield based on data from 46 hydrological stations in the sediment-rich region of the Yellow River from 1955 to 2010. The results showed that since 1970 sediment yield in the region has clearly decreased at different rates in the 45 sub-areas controlled by hydrological stations. The decrease in sediment yield was closely related to the intensity and extent of soil erosion control measures and rainstorms that occurred in different periods and sub-areas. The average sediment delivery modulus(SDM) in the study area decreased from 7,767.4 t/(km^2·a) in 1951–1969 to 980.5 t/(km^2·a) in 2000–2010. Our study suggested that 65.5% of the study area with the SDM below 1,000 t/(km^2·a) is still necessary to control soil deterioration caused by erosion, and soil erosion control measures should be further strengthened in the areas with the SDM above 1,000 t/(km^2·a).
基金funded by the National 973 Project China (2013CB733302)National Natural Science Foundation of China (41504014, 41474019)
文摘As critical component of hydrologic cycle, basin discharge is a key issue for understanding the hydrological and climatologic related to water and energy cycles. Combining GRACE gravity field models with ET from GLDAS models and precipitation from GPCP, discharge of the Yellow River basin are estimated from the water balance equation. While comparing the results with discharge from GLDAS model and in situ measurements, the results reveal that discharge from Mosaic and CLM GLDAS model can partially represent the river discharge and the discharge estimation from water balance equation could reflect the discharge from precipitation over the Yellow River basin.
基金jointly supported by the project of the China Geological Survey (DD20211309)the National Natural Science Foundation of China (41602273)the High-Level Talent Funding Program of Hebei province(A202101004).
文摘A large number of antibiotics have been discharged into rivers by human activities,posing a threat to aquatic ecosystems.The surface water of the Yellow River Basin also suffers antibiotic pollution,which hinders the improvement in the aquatic ecological environment.This study investigated and analyzed the characteristics and assessed the ecological risks of antibiotic pollution in surface water bodies such as canals,rivers and fish ponds in Kaifeng,Henan Province,which is a key city along the lower reaches of the Yellow River.The test results are as follows.A total of 15 types of antibiotics were detected in the surface water.They had a total antibiotic concentration of 12.2-249.9μg/L,of which tetracyclines(TCs)and quinolones accounted for the highest percentages.Six types of quinolones had detection rates of up to 100%,and doxycycline(DC)and oxytetracycline(OTC)had average concentrations of 29.52μg/L1 and 13.71μg/L,respectively.The major canals with water diverted from the Yellow River had total concentrations of quinolones and TCs of 22.0μg/L and 14.9μg/L,respectively,which were higher than those in previous studies.This phenomenon may be related to the decrease in the water flow of the Yellow River during the dry season and the increase in the antibiotic consumption of residents in the context of the Covid-19 outbreak.The upper reaches of the Huiji River in the Xiangfu District had higher antibiotic content than other districts in Kaifeng.Specifically,TCs accounted for 72.38%-91.84%of all antibiotics,and the DC and OTC concentrations were significantly higher than other antibiotics in the upper reaches.As indicated by the ecological risk assessment results,TCs had the highest ecological risks to green algae.Among them,DC had medium-high risks;TC,OTC,and chlortetracycline(CTC)had medium-high risks;trimethoprim(TMP)and lomefloxacin(LOM)had low risks;other TC antibiotics had no risk.Compared with green algae,most antibiotics showed higher ecological risks to daphnia and lower ecological risks to fish.DC and OTC dominate antibiotic pollutants in the surface water in Kaifeng City,and especially in Xiangfu District,where DC and OTC have medium-high risks.The TCs in the major Yellow River showed medium risks to both green algae and daphnia.It can be speculated that the antibiotic pollution in the Yellow River might pose a certain threat to the ecological security of water in Kaifeng City.
文摘Since the 1990s, the Yellow River stream has been temporarily interrupted for several years, which affects the development of society, the economy and human life, limits the economic potential of the drainage areas, and especially causes great harm to regions on the lower reaches. Based on the analysis of the relationship between the development of society and economy and water scarcity, the author thinks it is necessary to optimize and adjust the industrial structure that has extravagantly consumed enormous amounts of water, and to develop ecological agriculture, industry and tourism which are balanced with the ecological environment. Finally, the author puts forward several pieces of advice and countermeasures about how to build the economic systems by which water can be used economically.
基金Under the auspices of National Natural Science Foundation of China(No.41971128,41371104)the Award Program for Min River Scholar in Fujian Province(No.Min 201531)。
文摘To determine the pollution levels and potential toxic risks of arsenic(As) and heavy metals(Cr, Ni, Cu, Zn, Pb and Cd) in water and suspended particulate matter(SPM) in tail reaches(including freshwater reach and low-salinity reach) of the Yellow River as the Flow-Sediment Regulation Project(FSRP) has been carried out for approximately 15 yr, the surface water and SPM were sampled at pre-flood(April) and post-flood seasons(October). Results showed that similar changes of As and metal levels in water and SPM were observed along the tail reaches at pre-flood or post-flood season. Compared to pre-flood season, the levels of As, Cu, Cr and Ni in freshwater reach and the concentrations of Cr and Ni in low-salinity reach rose greatly at post-flood season. The levels of As and metals in SPM of freshwater reach or low-salinity reach at pre-flood season were significantly higher than those at post-flood season(P < 0.01).The pollutions of As and metals in surface water of tail reaches at pre-flood or post-flood season were not serious. The SPM in freshwater reach at pre-flood season were polluted by Cd, As, Cr, Cu and Ni while those in low-salinity reach were polluted by Cd and Cr. The SPM in freshwater reach at post-flood season were polluted by Cd and Pb while those in low-salinity reach were polluted by Cd and Cr.Cd was identified as heavy metal of primary concern at both pre-flood and post-flood seasons. Combined with the existed data reported in present research, this study found that the toxic risk of As and metals in SPM of tail reaches at pre-flood season was higher than that at post-flood season, implying that the implementation of FSRP during flooding season, to a great extent, reduced the toxic risk of these elements. With the long-term implementation of FSRP, the pollution levels of As and metals(particularly for Cd) in SPM of tail reaches might be elevated and the potential toxic risk primarily produced by Cr, Ni and As might be increased if effective measures were not taken in future.
文摘Based on the isotope analysis result of water samples in the 18 sections of the Yellow River, the variation of δ 18 O and δD have been analyzed. From near the source to the entrance to the sea, the Yellow River has a general trend that the ratios of the stable isotope increase progressively; The main factors affecting the isotopes in the river water are mixing of external water bodies,evaporation and others; In the river segment between Lanzhou and Baotou and in lower reaches, the extent of the evaporation effect on the isotope fractionation from the river water surface is limited but the evaporation from the irrigated river water and the return flow is one of the main factors affecting the isotopes in river water.
基金supported by the National Key Research and Development Program of China(No.2018YFC1407 601)the National Natural Science Foundation of China(No.41176064)
文摘In order to examine the impacts of water-sediment regulation on regional carbon cycling,we collected water,particulate and sediment samples from the middle-lower Yellow River in late June and early July,2015 and analyzed their specific amino acids(AA),DOC,POC,and bacteria abundance.Summarized by 14 specific AA,the total hydrolysable AA(THAA),particulate AA(PAA),and sediment AA(SAA)varied in ranges of 2.29-9.05μmol L^-1,5.22-22.96μmol L^-1,and 81.7-137.19μg g^-1 dry weight.After the regulation,dissolved free AA(DFAA)decreased by 29%while DCAA increased by 72%.These variations suggested that DFAA were further degraded,while DCAA molecules were further activated.Meanwhile,PAA increased almost 4 times as many as those before regulation,and SAA increased as well.After regulation,the amounts of bioactive amino acids(Asp,Glu and Gly)increased in THAA but decreased in PAA,with little changes in SAA.The ratios of Asp/Gly in different phases increased after regulation,indicating the AA contributions were promoted by calcareous organisms rather than by siliceous organisms.Multiple correlation analysis showed that PAA was primary representatives of AA and organic carbon,followed by DCAA and POC.Moreover,bacterial reproduction played a key role in shaping the AA compositions and properties,followed by the redox condition and acid-base balance.The results of this study provided a clear evidence for the effects of water-sediment regulation on regional biogeochemistry of organic carbon in the middle-lower Yellow River.
文摘The paper describes the water resources in the irrigated area of Ningxia, China, andthe methods for improving the utilization of the water resources, and puts forward somesuggestions so as to utilize the water resources rationally. The history of irrigation farming in Ningxia can be traced back to more than two thou-
基金supported by funding from the National Natural Science Foundation of China(Grant Nos.41530529 and 91737103)
文摘An underlying wetland surface comprises soil, water and vegetation and is sensitive to local climate change. Analysis of the degree of coupling between wetlands and the atmosphere and a quantitative assessment of how environmental factors influence latent heat flux have considerable scientific significance. Using data from observational tests of the Maduo Observatory of Climate and Environment of the Northwest Institute of Eco-Environment and Resource, CAS, from June 1 to August 31, 2014, this study analysed the time-varying characteristics and causes of the degree of coupling(Ω factor)between alpine wetlands underlying surface and the atmosphere and quantitatively calculated the influences of different environmental factors(solar radiation and vapour pressure deficit) on latent heat flux. The results were as follows:(1) Due to diurnal variations of solar radiation and wind speed, a trend developed where diurnal variations of the Ω factor were small in the morning and large in the evening. Due to the vegetation growing cycle, seasonal variations of the Ω factor present a reverse "U" trend. These trends are similar to the diurnal and seasonal variations of the absolute control exercised by solar radiation over latent heat flux. This conforms to the Omega Theory.(2) The values for average absolute atmospheric factor(surface factor or total) control exercised by solar radiation and water vapour pressure are 0.20(0.02 or 0.22) and 0.005(-0.07 or-0.06) W/(m2·Pa), respectively. Generally speaking, solar radiation and water vapour pressure deficit exert opposite forces on latent heat flux.(3) At the underlying alpine wetland surface, solar radiation primarily influences latent heat flux through its direct effects(atmospheric factor controls). Water vapour pressure deficit primarily influences latent heat flux through its indirect effects(surface factor controls) on changing the surface resistance.(4) The average Ω factor in the underlying alpine wetland surface is high during the vegetation growing season, with a value of 0.38, and the degree of coupling between alpine wetland surface and atmosphere system is low. The actual measurements agree with the Omega Theory. The latent heat flux is mainly influenced by solar radiation.
文摘The issue on water environmental degradation in the source area of the Yellow River has been one of very serious ecological and socially economic problems. The temporal-spatial changes of water environment led to the decreasing of land capacity and river disconnecting. The status of water environmental degradation in this paper was analyzed based on the data and field investigation. The results indicated that the surface water area in the region has obviously decreased owing to the climate changes and human irrational use of water resources and the continuous lowering of the regional groundwater table and the steadily decreasing tendency of the flow rate in the source areas of the Yellow River.