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Our planet is increasingly threatened by degradation in water quantity and quality due to climate change, population growth and development pressures. Water shortage is one of the most challenging environmental problems to humankind in the 21st century under the changing climate. Water shortages and scarcity escalate risks to food security and economic viability. For decades, water management has been dominated by supply oriented paradigm of expanding the capacity of accessible water (e.g. building dams). While large scale infrastructure projects provided effective solutions for chronic water crises in the past, they have come at expensive, irreversible and delayed ecological, economic and social costs. As more questions are raised concerning over reliance on infrastructure solutions, discussions about a sustainable future suggest a greater focus on the demand side of the equation is needed. In this paper, we use multi-recursive and runoff coefficient analysis methods to analyze the annual runoff of the mainstreams (Kuye River, Tuwei River, Wuding River and Jialu River) in the middle reaches of Yellow River. The main objective is to estimate the impacts of climate change and human activity on water resources in the study area and test the potential of water demand management to lessen the gap between supply and demand. Results show remarkable drop in the average annual runoff as a combined effect of climate change and human activity. Moreover, results show that human activities are the direct reason for the changes of river runoff, and the proportion of human activities account the biggest is Wuding river, next is Kuye river, Jialu river is smallest, these changes lead to the decrease of river runoff, and even drying up in recent years. This result highlights the importance of using WDM to diminish the increasing gap between demand and supply. Motivated by this, the paper presents a comprehensive framework for implementation WDM in the middle reaches of Yellow River. The framework includes a wide range of instruments: legislative, economic, technological and educational. The core step of the framework, collaboration among water planners, water service providers and end-users lies as an essential mechanism for achieving long term trade-offs between ecological and socio-economic water needs. [ABSTRACT FROM AUTHOR]

Reservoir sedimentation usually occurs in rivers that carry heavy amounts of silt. Setting reasonable schedules for drainage hole operations can balance the reservoir sediment levels and downstream river morphology. China's Yellow River is well known for its abundant sediment supply. The Xiaolangdi Reservoir is the key control project for the main stem of the Yellow River, and its sediment accumulation is especially serious. Preventing sedimentation before the gates is an important issue. The characteristics of the flow and sediment before the intake towers under scheduled drainage hole operations should be thoroughly researched. In this study, a three-dimensional numerical model was established based on MIKE 3. Variations of the flow structure, sediment concentration, and sedimentation elevation were the parameters studied under the scheduled operations. The results showed that the features of the bend flow are developed during the model phase. The velocity distribution in the vertical direction does not follow the general logarithmic distribution law of open channels. Scouring funnels appear during the development of the sedimentation surface before the intake towers. The sedimentation elevation is lower than the permissible value and has no influence on gate operations. This paper can provide a reference for similar research. [ABSTRACT FROM AUTHOR]

Yellow River, is designated as 'the cradle of Chinese civilization' and played a key role not only in the country's economic development but also in the historic and cultural identity of the Chinese people. With the rapid economic development and population growth, water demand for industry and households has increased significantly in the Yellow River basin; this has caused an increasing gap between water supply and demand. Competing water demands triggered conflicts between disparate water users on different scales such as the rich and the poor, or between different sectors and regions, such as domestic and agriculture, agriculture and industry, upstream and downstream, rural and urban areas, etc. Ensuring equity in water supply for conflicting water users is one of the major challenges that facing water managers and in particular water management in the Yellow River basin. In this paper, a method has been developed to calculate the Gini coefficient of water use as an indicator to measure the equality in domestic water supply. A dual domestic water use structure model is employed for this purpose. The developed method is subsequently applied to assess the equality in domestic water supply in the Yellow River. Data of population growth, domestic water use and economic development over the time period 1999-2006 are used to calculate the Gini coefficient of water use over the same length of period. The result shows a decreasing trend in Gini coefficient of domestic water use in the Yellow River basin after 2001 which means domestic water use is becoming more and more equitable in the basin. The study justifies that the Gini coefficient of water use can be used and recommended as a useful tool for the water management especially in the context of global change. [ABSTRACT FROM AUTHOR]

Water resources allocation in a river basin is customarily determined based on long-term mean water availability. However, inter-annual variability of water resources caused by climate fluctuation should also be considered in order to keep an effective and flexible allocation policy. This paper analyzes the historical evolution of the water resources allocation system in the Yellow River basin of China. Based on the concept of water use flexible limit to water shortage and actual water use data from 1988-2006, a set of flexible limits to water shortage adapted to the Yellow River basin has been proposed. This includes total water use flexible limit to water shortage for all provinces, which is approximately 70%; and the different water use flexible limits to water shortage for each social sector, which are approximately 90% for agriculture, 85% for domestic use, and 50% for other industries. It offers a simple, yet effective, method for future water resources allocation in the Yellow River basin to achieve the optimal use of water resources. It likewise provides a beneficial reference for water resources management in the water deficient regions of China. [ABSTRACT FROM AUTHOR]

The heavy sediment load of the Yellow River makes it difficult to simulate sediment concentration using classic numerical models. In this paper, on the basis of the classic one-dimensional numerical model of open channel flow, a variational-based data assimilation method is introduced to improve the simulation accuracy of sediment concentration and to estimate parameters in sediment carrying capacity. In this method, a cost function is introduced first to determine the difference between the sediment concentration distributions and available field observations. A one-dimensional suspended sediment transport equation, assumed as a constraint, is integrated into the cost function. An adjoint equation of the data assimilation system is used to solve the minimum problem of the cost function. Field data observed from the Yellow River in 2013 are used to test the proposed method. When running the numerical model with the data assimilation method, errors between the calculations and the observations are analyzed. Results show that (1) the data assimilation system can improve the prediction accuracy of suspended sediment concentration; (2) the variational inverse data assimilation is an effective way to estimate the model parameters, which are poorly known in previous research; and (3) although the available observations are limited to two cross sections located in the central portion of the study reach, the variational-based data assimilation system has a positive effect on the simulated results in the portion of the model domain in which no observations are available. [ABSTRACT FROM AUTHOR]

Water shortages have become one of the most severe problems in semi-arid regions throughout the world. Although semi-arid regions have always been dry, human activities and climate change are acerbating the problem. In Chinese Yellow River basin, the river is the major source of freshwater for those living there, and they have long suffered from serious water shortages. However, increasing population and decreasing streamflow are making these shortages more acute. This study seeks to quantify changes in available water in the Yellow River basin over the last 100 years and attempts to determine causes for these changes. To do this, the study evaluated changing trends and regime shifts of streamflow using long term historical records at different hydrological stations in the Yellow River basin over the past century. The results show that annual streamflow has a significant decreasing trends (P < 0.01) in the mid-lower reaches of the basin. Streamflow decomposition by the breaks for additive seasonal and trend approach suggest that this trend can be decomposed into four distinct annual stages (1919-1933, 1934-1969, 1970-1986 and 1987-2011), while the seasonal component demonstrated an evident regime shift in 1986. This regime shift is mainly related to the construction of large reservoirs in the basin. The flow duration curves illustrate a decrease in the magnitude of streamflow over the last century with a relatively uniform flow regime at all stations. The reconstructed streamflow at Toudaoguai station suggests that agricultural irrigation is predominantly responsible for streamflow reductions between Lanzhou and Toudaoguai stations with approximately 9.1 km/a of water extracted between 1997 and 2006. Meanwhile, a decrease of incoming water from upper reaches and soil and water conservation measures were responsible for the significant decline in annual streamflow at mid-lower reaches station. The result of this paper should be of use for water resources planning, watershed management and climate adaptation as they demonstrate how natural and anthropogenic drivers influence water availability in semi-arid regions. [ABSTRACT FROM AUTHOR]

Siltation of coarse sediment in the river channel is the main cause of flooding and dike burst on China's Yellow River, and the loess are thought as the coarse sediment sources of the lower reach of the Yellow River. The Ningxia-Inner Mongolia reaches of the Yellow River flow through an extensive area of aeolian desert, with flood events occurring frequently in this region. In this paper, we investigate the trace element contents of the coarse sediment in the Ningxia-Inner Mongolia reaches of the Yellow River. The main chemical components of the coarse sediments consist of 28 trace elements. Correlation analysis and factor analysis of 21 of these trace elements indicates that Ti and Zr are stable indicators of the coarse sediment sources. Comparing the spatial distribution of some of the main trace elements to major sources and riverbed sediment of the main reaches of the Yellow River suggests that the coarse sediments deposited in the Ningxia-Inner Mongolia reaches are mostly controlled by the local sediment sources. The results of R-factor analysis further proved that desert sand, riverbank material, and the Ten Tributaries are the primary sources of the coarse sediment in the Ningxia-Inner Mongolia reaches of the Yellow River. [ABSTRACT FROM AUTHOR]

Runoffs in the Yellow River and Yangtze River basins, China, have been changing constantly during the last half century. In this paper, data from eight river gauging stations and 529 meteorological stations, inside and adjacent to the study basins, were analyzed and compared to quantify the hydrological processes involved, and to evaluate the role of human activities in changing river discharges. The Inverse Distance Weighted (IDW) interpolation method was used to obtain climatic data coverage from station observations. According to the runoff coefficient equation, the effect of human activities and climate can be expressed by changes in runoff coefficients and changes in precipitation, respectively. Annual runoff coefficients were calculated for the period 1950-2008, according to the correlation between respective hydrological series and regional precipitation. Annual precipitation showed no obvious trend in the upper reaches of the Yellow River but a marked downward trend in the middle and downstream reaches, with declines of 8.8 and 9.8 mm/10 a, respectively. All annual runoff series for the Yellow River basin showed a significant downward trend. Runoff declined by about 7.8 mm/10 a at Sanmenxia and 10.8 mm/10 a at Lijin. The series results indicated that an abrupt change occurred in the late 1980s to early 1990s. The trend of correlations between annual runoff and precipitation decreased significantly at the Yellow River stations, with rates ranging from 0.013/10 a to 0.019/10 a. For the hydrologic series, all precipitation series showed a downward trend in the Yangtze River basin with declines ranging from about 24.7 mm/10 a at Cuntan to 18.2 mm/10 a at Datong. Annual runoff series for the upper reaches of the Yangtze River decreased significantly, at rates ranging from 9.9 to 7.2 mm/10 a. In the middle and lower reaches, the runoff series showed no significant trend, with rates of change ranging from 2.1 to 2.9 mm/10 a. Human activities had the greatest influence on changes in the hydrological series of runoff, regardless of whether the effect was negative or positive. During 1970-2008, human activities contributed to 83% of the reduction in runoff in the Yellow River basin, and to 71% of the increase in runoff in the Yangtze River basin. Moreover, the impacts of human activities across the entire basin increased over time. In the 2000s, the impact of human activities exceeded that of climate change and was responsible for 84% of the decrease and 73% of the increase in runoff in the Yellow River and Yangtze River basins, respectively. The average annual runoff from 1980 to 2008 fell by about 97%, 83%, 83%, and 91%, compared with 1951-1969, at the Yellow River stations Lanzhou, Sanmenxia, Huayuankou and Lijin, respectively. Most of the reduction in runoff was caused by human activities. Changes in precipitation also caused reductions in runoff of about 3%, 17%, 17%, and 9% at these four stations, respectively. Falling precipitation rates were the main explanation for runoff changes at the Yangtze River stations Cuntan, Yichang, Hankou, and Datong, causing reductions in runoff of 89%, 74%, 43%, and 35%, respectively. Underlying surface changes caused decreases in runoff in the Yellow River basin and increases in runoff in the Yangtze River basin. Runoff decreased in arid areas as a result of increased water usage, but increased in humid and sub-humid areas as a result of land reclamation and mass urbanization leading to decreases in evaporation and infiltration. [ABSTRACT FROM AUTHOR]

The major obstacles to simulating flood flow in the Yellow River are its high sediment concentration, complex compound cross section, and rapid change in channel planform. This paper presents an improved one-dimensional numerical model that takes into account the effect of sediment concentration and bed change on mass and momentum conservation of flood flow in the Yellow River. The model is calibrated and then validated by simulating three individual flood events. Results show that an increase in sediment concentration leads to a reduction in flood wave celerity and peak discharge. The generalized likelihood uncertainty estimation (GLUE) method is used to evaluate the uncertainty of modeling results. A sensitivity index, analogous to the Nash-Sutcliffe efficiency factor, is adopted to quantify the sensitivity of calibration parameters. The modeling results are sensitive to the choice of Manning's roughness coefficient and the empirical recovery coefficient for suspended sediment transport at reaches of transitional channel planform. [ABSTRACT FROM AUTHOR]

The paper reviews some representative etymologies so far suggested for Hé 'the Yellow River'. It pays particular attention to the methodologies involved in etymological enquiries. There are basically two of them. One is the comparative method as developed in the Indo-European languages and applied to the Sino-Tibetan and Tibeto-Burman languages. Another one is a traditional method based on the evidence available in Chinese itself. It has roots in Sòng times (ca. 13th c). Known widely as Chinese word-family studies the first systematic work is by a Japanese scholar Tōdō Akiyasu (1914-1985) in his D. Lit. thesis entitled Jōko Kango no tango kazoku no kenkyû (Tokyo University, 1962). Its revised and enlarged version (1965) and other notable works are critically discussed. There is no doubt that Chinese language was used before the emergence of oracle-bone inscriptions (abbreviated hereinafter as OBI) ca. 1230 B.C. (lasting to ca. 1046 B.C.), but the phonological and morphological reconstructions we have for Old Chinese cannot be considered to precede the date of the emergence of OBI. We have thus redefined etymology: it studies the earliest attested meanings of words, of their relationship to those in different languages thought of the same origin, and in the case of many words, but not all of them, be considered in terms of the interface of palaeography and etymology. This paper thus attempts to bridge the two disciplines. Even though the Shāng scribes may not have been the creators of the graphs themselves, they must have continued the traditions of the original graph makers. The Shäng scribes lived more than a thousand years earlier than the users of the clerical script of Hàn time. Many bone and bronze graphs reflect the words they were writing, often subtly mirroring their meanings. How this last aspect has bearing on the etymology of Hé is the major theme of this paper. Not only linguistic but also palaeographical and archaeological analyses in this paper have led to a conclusion that the etymology of Hé is related to both the phonetic and shape of an adze handle, kē/*khâi. This in and of itself is not new, but other details are novel including a finer analysis of the predecessors of written like and as well as that of such Zhōuyuán graphs as and. The former graph consists of the water element and a standing human figure with its head turning backward and carrying a pole with some load. The latter one consists of the water element and a similar human figure, but the carrying pole and the load are abbreviated. The DT of the former is the latter. These forms reflect a scribal tradition different from the predecessors of, and the word represented by these forms is hé/*gâiB 'to carry on the shoulder' and because the sound was close to hé/*gâi, actually closer than kē/*khâi was to it, the graph was loaned to express the Yellow River, Hé. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of Engineering Geology & the Environment is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract This paper presented the historical data on the temporal trends of polybrominated diphenyl ethers (PBDEs) in the sediment cores collected from the Huaihe River, Yellow River and Chaohu Lake, China. Among the 40 targeted PBDE congeners, only 10, 6, and 9 of them were detected respectively in the samples from the Huaihe River, Yellow River and Chaohu Lake. On average, the total PBDEs concentrations in sediments were highest in Chaohu Lake followed by the Huaihe River and the Yellow River. As compared to other PBDE congeners, BDE-209 had higher concentrations and detection rates. The similar down core variation between PBDEs and total organic carbon (TOC) suggests that TOC is an important factor influencing PBDEs distribution in the sediments. The total PBDEs concentrations showed an increasing trend from bottom to upper sediments before a decreasing trend in the topmost sediments. The rapid urbanization and industrialization of these regions in recent decades may cause the historically increasing concentrations of sedimentary PBDEs, especially BDE-209. The decreasing PBDEs concentrations in topmost sediments was probably related to the strict environmental policies at present. Graphical abstract Three sediment core samples were collected from Huaihe River, Yellow River and Chaohu Lake respectively in China. The sediment core date was determined using the Pb210 dating technique. PBDEs concentrations were analyzed by using GC-MS. Temporal trends of polybrominated diphenyl ethers (PBDEs) showed the increasing trends from bottom to surface and decreasing trends in the coming years. fx1 Highlights • 210Pb chronology was used to date the sediment core. • Historical variation of PBDEs was analyzed. • Vertical distribution and pollution source of PBDEs were elucidated. • Pollution history of PBDEs by anthropogenic activities was reconstructed. [ABSTRACT FROM AUTHOR]

The high sediment load of the Yellow River results in rapid infilling of its reservoirs when sediment is not regularly flushed. Simultaneously, the downstream reaches of the Yellow River experience extremely high siltation rates, which are reduced when sediment is retained in its reservoirs. To minimize siltation in the reservoirs and the downstream river bed, water and sediment are released from the reservoir in a controlled way through flushing experiments. In this paper, we analyze the effect of such a flushing event on the downstream river bed through data analysis and numerical modeling. Sedimentation may be minimized by relating the amount of sediment released from the reservoir to the sediment available for release through operational monitoring and by releasing relatively clear water after turbid water. Despite this flushing of sediment, the reservoir will eventually fill up, and more sediment released again into the lower Yellow River. The change in discharge magnitude and frequency brought about by the reservoir will then probably result in increased siltation rates in the lower Yellow River compared to the predam situation. [ABSTRACT FROM AUTHOR]

From AD 1048 to 1128, Yellow River flooding killed over a million people, left many more homeless and destitute, and turned parts of the once fertile North China Plain into a silted-up agricultural wasteland. Brought on in part by climate change and the Northern Song dynasty’s (AD 960–1127) mismanagement of the environment, the Yellow River floods likely hastened the collapse of the Northern Song dynasty. Despite the magnitude of this flood event, no sedimentary deposits have yet been linked to these historically recorded floods. In this research paper, we provide archaeological, sedimentary, and radiocarbon evidence of the AD 1048–1128 Yellow River floods at the Dazhanglongcun, Xidacheng, and Daguxiancun sites in Neihuang County, Henan Province. Based on our data, we argue that the AD 1048–1128 Yellow River floods deposited over 5 m of alluvium on villages in the North China Plain, radically changing both the physical and political landscape of Northern Song dynasty China. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Civil Engineering is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Using the measured data on no-flow events in the Lower Yellow River since 1972, this paper presents an approach to describe the no-flow status in terms of a comprehensive indicator. The severity levels of no-flow events are identified by cluster analysis. Furthermore, the relation between severity levels and incoming water from upstream and its variance is well established with a BP-typed Artificial Neural Network (ANN), which is helpful to identify the complex response of the severity level to flow characteristics. The availability of the approach for quantitative description and prediction of no-flow events is discussed through comparisons between predicted and measured results in the Lower Yellow River. [ABSTRACT FROM AUTHOR]

Transjurisdictional water pollution problems are increasing in number and are becoming a significant governance problem in China. A large number of transjurisdictional water pollution disputes that have far-reaching social effects are occurring between provinces and are also frequent between municipalities, counties, towns, and villages. In this paper, several transjurisdictional water pollution cases in China, particularly in the Yellow River Basin, are discussed. The problems and causes for transjurisdictional water pollution are addressed. There are many causes for transjurisdictional water pollution problems although the key reasons are the rapid economic development, the failure of local authorities to enforce the existing laws and to implement administrative decisions, as well as inadequacies in the legal framework. Other factors include poor technology, shortage of funds, the institutional division of jurisdiction and management over water quantity and quality both administratively and legally, the lack of transparency in the decision-making process, insufficient public participation and information disclosure, poor communication, and lack of involvement of stakeholders in basin or sub-basin organizations. [ABSTRACT FROM AUTHOR]

This study applies the cultural gene theory to preserving and inheriting Henan Yellow River cultural heritage, aiming to provide insights for the thorough exploration and optimal utilization of Yellow River cultural heritage resources. The extraction of Henan Yellow River cultural genes follows a process akin to extracting product genes in biological, genetic engineering. Utilizing reverse translation of instances of Henan Yellow River cultural elements and reverse transcription of instance populations, the Henan Yellow River cultural genes are extracted. A genealogy for constructing Henan Yellow River cultural heritage is established through the associative construction of genetic elements. The cultural genes are categorized and organized into three types which are core genes, ancillary genes, and hybrid genes. Tailored educational and communicative strategies can be adopted for different gene types, thereby offering a reference for the inheritance and preservation of Henan Yellow River cultural heritage and facilitating practical applications in relevant domains. [ABSTRACT FROM AUTHOR]

The uplift of the Tibetan Plateau was a significant event in terms of global landforms and climate, but the exact nature of the uplift process remains contested among geologists. In the uplifted inland area of the plateau, river-terrace formation has been controlled mainly by tectonic uplift, which means that analyses of river terraces are an excellent means of investigating the uplift process. In this paper, we establish the terrace sequence of the Yellow River in the Gonghe–Guide section of the northeastern Tibetan Plateau, making use of field investigations, gravel analysis, and electron spin resonance (ESR) dating. Terraces T3–T9 of the numbered sequence formed at ~ 0.13, 0.18, 0.23, 0.41, 0.85, 0.93, and 1.32 Ma, (moving backwards in time and upwards from the valley floor), whereas terraces T11–T20 formed at ~ 1.71, 1.75, 1.88, 1.94, 2.01, 2.12, 2.23, 2.31, 2.36, and 2.47 Ma. This suggests that the Yellow River existed in Gonghe and Guide basins for at least the last 2.47 Ma. The incision rates of the Yellow River in the Gonghe–Guide section indicate that there were three distinct phases of uplift of the northeastern Tibetan Plateau, occurring at different rates, with an average uplift rate of ~ 0.26 mm/yr during the Quaternary. These results support the multi-stage uplift model, which states that the Tibetan Plateau has experienced continuous uplift since 8 Ma, but contradicts both the early uplift theory, which holds that the uplift of the Tibetan Plateau occurred mainly before the Pliocene, and the notion of a late and rapid uplift of the plateau that began at 3.6 Ma. [ABSTRACT FROM AUTHOR]

The simulation performance of the land surface model Community Land Model 5.0 (CLM5.0) is tested by using the eddy correlation system and micrometeorological tower observational data at the Maqu observation field in 2016. The results show that the CLM5.0 model has a good simulation effect on the soil temperature and can well reflect the seasonal variation characteristics of soil temperature. In addition, the model can well simulate the seasonal variation in shallow soil moisture (5 cm and 10 cm). However, the deviations between the simulated and observed values are large. CLM5.0 cannot simulate the water holding capacity of shallow soil well, resulting in its underestimation. The simulation performance of the upward longwave radiation and net radiation is substantially better than that of the upward shortwave radiation due to the change in surface albedo caused by precipitation from March to July. CLM5.0 can also well reproduce the variation trend of the latent heat flux and 5 cm soil heat flux (heat exchange of soil at 5 cm). When the leaf area index (LAI) and Medlyn slope values are changed to 10%, 20%, and 50% of the default values, the simulation effects of soil moisture at depths of 5 cm and 10 cm are significantly improved, and the best simulation effects are achieved at 0.5 times the default values. This result indicates that lower LAI and Medlyn slope values are more suitable for simulating shallow soil moisture. [ABSTRACT FROM AUTHOR]

Objectives Under the background of global climate change, variations in streamflow and sediment discharge in the Yellow River would continue with intensified human activities and changes in the ecological environment. To harness the Yellow River, analyzing the degrees of change and the reasons for the streamflow and sediment discharge, as well as predicting the future trends, are urgently needed. Methods In this paper, the non-parametric Mann–Kendall test, Sen's estimator of slope, Pettitt's test and wavelet transform were applied to detect the trends, the magnitude of the trends and the abrupt changes and periodic variation in streamflow and suspended sediment discharge at eight hydrological stations from 1950 to 2013 along the mainstream of the Yellow River. Results Over the past 64 years (1950–2013), the spatial distribution of the annual average streamflow was of the “M” type, and the annual average suspended sediment discharge had a parabolic curve shape along the mainstream of the Yellow River. The temporal variation showed a distinct decreasing trend in streamflow since the 1990s and in suspended sediment discharge since the 1980s. Many cycles of oscillations occurred in the streamflow and suspended sediment discharge variation, leading to an alternate change in the wet/dry periods and the high/low sediment discharge periods. Conclusions In various regions of the Yellow River Basin since the 1970s, climate changes contributed reductions of 17.0–45.0% and 12.2–50.3% for streamflow and suspended sediment discharge, respectively, whereas human activities contributed reductions of 55.0–83.0% and 49.7–87.8%. Therefore, human activities were the major causes of the significant decline in the streamflow and the suspended sediment discharge of the Yellow River over the past six decades. Reasonable and possible measures should be taken to achieve water resources optimization and configuration and to promote watershed management and sustainability in the regions of the Yellow River Basin. [ABSTRACT FROM AUTHOR]

Abstract: Suspended sediment dynamics are still imperfectly understood, especially in the upper Yellow River where few studies on this issue have been conducted. This study analyzed the variability in suspended sediment concentration at different temporal scales (within-flood, monthly-seasonal and annual). Using a dataset up to 49years long (1954–2002) at Toudaoguai station, this paper provided insight into the characteristics of suspended sediment transport in the Ningxia-Inner Mongolia reaches of the upper Yellow River. The results show that, in a single flood event, changes in SSC are not simultaneous with changes in discharge, resulting in counterclockwise hysteretic loops, clockwise loops or figure-eight loops. The C–Q loops and sediment rating curves for different seasons had different characters. The diversiform C–Q loops in the Inner Mongolia reaches of the upper Yellow River may be mainly caused by the sediment inputs from tributaries, the different propagation velocity of sediment and water discharge, spatial and temporal storage–depletion processes of available sediment. At annual scale, the variations of annual mean discharge and SSC displayed a similar gradually deceasing trend, and the relation between water discharge and SSC during 1954–2002 could be described by a cubic polynomial function. Since the joint operation of Liujiaxia and Longyangxia reservoirs after 1986, the transport capacity of the Upper Yellow River has been much reduced. [Copyright &y& Elsevier]

Abstract: Reservoir sedimentation has been a serious problem for reservoir operation and watershed management worldwide, which highlights the importance of accurate estimate of the deposited sediment amount. With reservoir information derived from remote sensing dataset and observed hydrological records of water and sediment, this paper is concerned with the cumulative reservoir sediment trapping in the Yellow River basin. The river basin was divided into 12 sub-basins, upon which the reservoirs'' sediment trapping efficiency (TE) and their interception effects on inflowing sediment were estimated with sediment records extracted from 179 field sampling stations. The results show that, with the sediment TE greater than 80% for all the sub-basins, theoretically the basin-wide reservoirs are able to trap most sediment. For the whole river basin, the sediment TE averages 95.2%, which indicates that the reservoirs can collectively make a significant anthropogenic signature on basin-wide sediment delivery. A basin-wide sediment yield map was generated to estimate the reservoir sedimentation amount. During 1950–1970, annually about 2.483Gt of sediment was transported into channels from sloping lands. Taking into account the actual water storage changes and the reservoir construction history, the actual reservoir sedimentation rate was estimated at 0.59Gt/yr after corrections, which represents 47.6% of the river basin''s total sediment load reduction. Globally, reservoir sedimentation in the Yellow River basin represents about 12–15% of the global mean rate. Up to 2010, approximately 19.32Gt of sediment has been trapped by Yellow River reservoirs, and totally about 40.32Gt of sediment has been artificially fixed if silt check dams are also considered. With huge amounts of sediment deposited, these reservoirs have been losing their storage capacity to sedimentation at a rate of 0.6% per year. The magnitude is expected to enhance in future following new reservoir completions. Thus, more efforts are strongly needed to explore the associated responses. [Copyright &y& Elsevier]

Abstract: The Yellow River (Huang He) downstream of the Jinshaan Canyon displays well-preserved fluvial terrace sequences below an extensive planation surface at the northeastern Ordos Plateau. Despite a series of well developed geomorphic surfaces, the landscape evolution of the plateau is largely unconstrained. The Jinshaan Canyon, formed by the deeply incising Yellow River through the Ordos Plateau, provides keys to understanding the landscape evolution of this Plateau with respect to the nearby northeastern margin of the Tibetan Plateau. This paper presents two sets of magnetostratigraphic results derived from the aeolian deposits (Red Clay and loess) on the planation surface and the uppermost Yellow River terrace in the middle part of the Jinshaan Canyon. Magnetostratigraphic analysis reveals that the planation surface and the uppermost Yellow River terrace formed respectively at circa 3.7Ma and circa 1.2Ma ago. The Ordos Plateau is the product of a period of planation culminating just before circa 3.7Ma and then was interrupted by an episode of uplift, which may be correlated with the accelerated growth of the Tibetan Plateau in the Miocene–Pliocene. The drainage system in the Jinshaan Canyon was re-organized around 3.7Ma. No correlation seems to exist between an older drainage existing prior to circa 3.7Ma and the present Yellow River network in the Jinshaan Canyon, even though sedimentary and tectonic evidence suggests that the drainage in the middle reach of the Yellow River formed in the late Miocene-early Pliocene. The Yellow River has developed its rectangular course around the Ordos Plateau only since circa 3.7Ma. [Copyright &y& Elsevier]

Summary: Turbidity currents play a critical role in effective sediment and reservoir management in alluvial rivers. Yet previous estimations of reservoir turbidity currents are mostly based on simple empirical relations and it remains unclear how and to what extent physically based numerical models can resolve current evolution as compared against field observations. This paper presents a physically-based,process-resolved computational study of turbidity currents in the Xiaolangdi reservoir in the lower Yellow River, China. A coupled layer-averaged 2Dnumerical model is applied, which explicitly incorporates the interactions between the current, sediment transport and morphological evolution, and features a new well-balanced numerical scheme dealing with irregular topography. Two turbidity current events in July 2004 are numerically simulated to calibrate and validate the model. The current advance and the sediment transport rate computed by the model compare favourably with field measurements. These suggest the present model is a viable tool for determining the timing for operating the bottom outlets, which is critical for effective reservoir sediment management. The sediment entrainment flux and bed resistance are key factors dictating the evolution of turbidity current and warrant further investigations. [ABSTRACT FROM AUTHOR]

Abstract: The suspended sediment deposition (SSD) in the alluvial reach between the Qingtongxia station and the Toudaoguai station of the upper Yellow River has shown a dramatic variation since 1952. However, its spatial and temporal changing pattern and driving factors are still not clear. This paper examines the detailed spatial and temporal variations of the SSD based on the annual suspended sediment load at five gaging stations located in this alluvial reach in 1952–2007. The mean annual SSDs in four sub-reaches (Qingtongxia–Shizuishan, Shizuishan–Bayangaole, Bayangaole–Sanhuhekou, and Sanhuhekou–Toudaoguai) were calculated and analyzed for different periods. The mean annual kilometric SSDs in 1952–2007 were −0.228∗105, 0.97∗105, 0.165∗105 and 0.006∗105 ta−1 km−1 in the four sub-reaches, respectively, with the highest SSD occurred in the Shizuishan–Bayangaole sub-reach. Results also suggested that SSD was mainly accumulated in 1952–1959 before major reservoirs were constructed and in 1986–2007 after three major reservoirs (Qingtongxia, Liujiaxia and Longyangxia) were constructed in the main stream. During 1960–1985, all sub-reaches except the Shizuishan–Bayangaole sub-reach experienced channel erosion. Although climate change may play some roles, the changes in SSD were mainly influenced by human activities. In particular, the water and soil conservation actions, such as the construction of check dams from 1958 in upper stream tributaries, intercepted significant amount of suspended sediment and cause the net erosion of the main channel in the 1960s. The operation of the Qingtongxia reservoir reduced the SSD in this downstream reach in the 1970s and 1980s because upper stream suspended sediment was trapped by the reservoir and reservoir-released relative clear water scoured the downstream channel. Although the Liujiaxia and Longyangxia reservoirs trapped relatively small amount of suspended sediment, they stored a large amount of water during the flood season, reducing the discharge and the erosion capability of the downstream flow. Therefore, this operation mode may increase the SSD in this river reach. In addition, with the gradual loss of the Qingtongxia reservoir''s capacity in sediment storage, more suspended sediment was released to the downstream channel, causing strong SSD in this reach after 1990. [Copyright &y& Elsevier]

Abstract: Delayed response means that channels cannot achieve a new equilibrium state immediately following disruption; the channel requires a response time or relaxation time to reach equilibrium. It follows that the morphological state of fluvial system represents the cumulative effects of all previous disturbances and environmental conditions. A unique feature of the delayed response model for bankfull discharge is that the model is capable of representing the cumulative effects of all previous flow conditions when applied to predict the path/trajectories of bankfull discharge in response to altered flow regimes. In this paper, the delayed response model was modified by readjusting the weight for the initial boundary conditions and introducing a variable β with respect to time. The modified model was then applied to the bankfull discharge calculations for three selected river reaches of the Yellow River, with each reach having different geomorphic settings and constraints. Results indicated that the modified model can predict accurately the bankfull discharge variation in response to changes in flow discharge and sediment load conditions that have been dramatically altered in the past. Results also demonstrated the strong dependence of current bankfull discharge on the previous years'' flow conditions, with the relaxation time varied from 2 to 14 years, meaning that the bankfull discharge was not only affected by the flow discharge and sediment load in the current year, but also by those in previous 1 to 13 years. Furthermore, the relaxation time of bankfull discharge adjustment was inversely proportional to the long-term average suspended sediment concentrations, and this may be explained by fact that high sediment concentrations may have a high potential to perform geomorphic work and there is more sediment readily available to shape the channel boundary and geometry. [Copyright &y& Elsevier]

Abstract: Water discharge and sediment load have changed continuously during the last half century in the Yellow River basin, China. In the present paper, data from 7 river gauging stations and 175 meteorological stations are analyzed in order to estimate quantitatively the contributions of human activities and climate change to hydrological response. Coefficients of water discharge (C w ) and sediment load (C s ) are calculated for the baseline period of 1950s–1960s according to the correlations between the respective hydrological series and regional precipitation. Consequently, the natural water discharge and natural sediment load time series are reconstructed from 1960s–2008. Inter-annual impacts are then separated from the impacts of human activities and climate change on the hydrological response of different regions of the Yellow River basin. It is found that human activities have the greatest influence on changes to the hydrological series of water discharge and sediment load, no matter whether the effect is negative or positive. Moreover, the impact of human activities is considerably greater on water discharge than sediment load. During 1970–2008, climate change and human activities respectively contribute 17% and 83% to the reduction in water discharge, and 14% and 86% to the reduction in sediment yield in the Upper reaches of Yellow River basin; The corresponding relative contributions in the Middle reaches are 71% and 29% to reductions in water discharge, and 48% and 52% to reductions in sediment load. Moreover, it is observed that the impacts of human activities on the whole basin are enhanced with time. In the 2000s, the impact of human activities exceeds that of climate change in the 2000s, with human activities directly responsible for 55% and 54% of the reductions in water discharge and sediment load in the whole basin. [Copyright &y& Elsevier]

Abstract: Long-term changes to the Yellow River delta in China have received considerable attention not only because of the growing economic importance of the delta region but also because they provide a clear example of the dominant role played by anthropogenic effects upon a large dynamic river delta. This paper presents a detailed study on the morphological consequences of reduction in river sediment load and influence of human activities based on sediment load data at three gauging stations in the upper, middle and lower reaches of the Yellow River basin from 1950 to 2007. The results indicate that sediment loads at all three gauging stations display a gradually decreasing trend over the past 58years. The primary reason for this decrease is shown to be due to various human activities, including the construction of Longyangxia and Liujiaxia reservoirs in the upper reaches, water–soil conservation practices and the commissioning of Sanmenxia and Xiaolangdi reservoirs in the middle reaches. It is estimated that water–soil conservation practices which are a major factor to the decrease of sediment load at Huayuankou gauging station account for 40% of the total amount of reduction, sediment trapping by Sanmenxia and Xiaolangdi reservoirs account for 30% of the total amount of reduction and the 10% decrease is caused by human activities in the upper reaches. The remaining 20% decrease is attributed to precipitation decrease. The reduction of sediment load has directly impacted on the lower Yellow River and the delta region, causing alternate changes between siltation and scouring in the lower river channel along with an increased rate of erosion over the whole Yellow River delta. [Copyright &y& Elsevier]

Abstract: This paper is to examine the water quality of the Yellow River basin on the basis of collated data of nitrogen (40 years) and phosphorus (20 years), and also of the relevant chemical fertilizer application, population, and industrial wastewater, etc. Relationship among these elements was discussed in order to explore their causal links, in relation to the temporal variation of nitrogen and phosphorus transportation. Results indicate that the transported nitrogen load in the lower Yellow River has had an increasing trend during the past 40 years but declined considerably in the later 1990s due to the reduction in flow discharge that led to desiccation of the lower reaches of the Yellow River. Whereas, nitrogen contribution to the estuary from Huayuankou to Lijin reach was minus due to the large amount of water diversion from the Yellow River for irrigation purpose. Phosphorus content fluctuated within a certain range without any tendency, but also decreased in the later 1990s due to the desiccation in the lower reaches. Our analysis indicates that nitrogen load in the Yellow River has been mainly impacted by population growth and nitrogen fertilizer application, but showed no statistically significant relationship with wastewater loads. In contrast, total phosphorus content in the Yellow River showed no relationship with population, fertilizer use and wastewater discharge in the basin, but presented significant correlation with suspended solids concentration of the Yellow River. Calculations indicate that the phosphorus content in suspended solids of the Yellow River was 0.54g/kg, which is quite close to the background value of phosphorus in the soil of the Loess Plateau – the intensive soil erosion area in China, through which the Yellow River flows. Therefore, we conclude that phosphorus transportation in the Yellow River is dominantly controlled by soil erosion from the Loess Plateau. The results are significant for estuarine management in that nitrogen, a key factor in marine eutrophication, is chiefly from anthropogenic sources whereas the large phosphorus loads are controlled by erosion of loess soils. [Copyright &y& Elsevier]

Abstract: Investigations of river terraces are often seriously hindered by difficulties in dating the formation of terraces using conventional and well-established methods such as 14C dating. In this paper, recently developed optical dating techniques were applied to a Yellow River terrace sequence in the Hequ area, Shanxi Province, China. Based on field investigations, four terraces were identified. Systematic sampling for optical dating was carried out on these terrace deposits. The single-aliquot regenerative-dose method was used to determine equivalent dose. By analyzing the degree of bleaching of fluvial samples, maximum and minimum optical ages were obtained for these samples. The minimum optical dates obtained are geomorphologically and stratigraphically consistent with each other, suggesting that the dates are reliable. The formation ages of the four terraces are 3.4∼10, 20∼25,∼30 and ∼90 ka, respectively. On the basis of these optical dates, the geomorphological evolution of the terrace sequence was established, and the factors affecting the terrace development discussed. [Copyright &y& Elsevier]

Abstract: This paper evaluates the applicability of the sediment transport methods developed by Engelund and Hansen, Ackers and White, Yang et al., and van Rijn, together with the Wuhan methods developed in China, to the Yellow River, which has highly concentrated and fine-grained sediment. The sediment data includes over 1000 observations from the Yellow River, 32 sets of data from a canal, and 266 sets of data from laboratory flumes. The best predictions were obtained by the Yang 1996 method, the Wuhan method, and the modified Wuhan method by Wu and Long, while reasonably good predictions were also provided by the van Rijn 2004 method. The Engelund and Hansen, the Ackers and White, and the van Rijn 1984 methods in their original forms are not applicable to the Yellow River. The predicted results for total load concentrations were as good as for bed-material concentrations, even though the total load includes a large portion of wash load. [Copyright &y& Elsevier]

In this paper, the changes in runoff and sediment yield have been assessed by using long-term observation data from 9 gauging stations on the Yellow River and 12 climate stations in the Yellow River watershed in China. It was observed that the annual precipitation depth at 3 climate stations in the headwater region of the Yellow River has an upward trend. However, in the lower section of the Upper Reach sub-watershed of the Yellow River, the annual precipitation depth has a slightly downward trend. In the Middle Reach sub-watershed, annual precipitation depth has a clear downward tendency. In the Lower Reach sub-watershed of the Yellow River, annual precipitation depth has a slightly upward tendency. Results indicate that, both annual sediment yield and annual runoff depth have a tendency of reduction in the past half century. The annual sediment yield in the Middle Reach is extremely high, with a long-term annual sediment yield of 1543.65 t/km² at the Longmen station and 1631.39 t/km² at the Tongguan station. In the Lower Reach, both annual runoff depth and sediment yield have a clearly downward trend. However, the long-term average annual sediment yield in the Lower Reach varies from 1035 to 1330 t/km2 which is still extremely high but less than those at gauging stations on the Middle Reach. The average annual sediment yield decreased significantly in recent 10 years. Examplewise, for the Yellow River at Lijin Station, the average runoff depth of the recent 10 years is only 1/3 of the long-term average value, and the average annual sediment yield of the recent 10 years is only 1/4 of the long-term average value. Additionally, the impacts of human activities on both runoff depth and sediment yield have been discussed. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, the changes in the annual runoff and sediment transport have been assessed by using the long term observation data from 10 gauging stations on 10 large rivers across China from far north to far south. It is found that the annual sediment yield has generally had a decreasing trend in the past half century. According to the changes in annual runoff and the sediment yield per area, rivers in China can be classified into the following three groups: 1) rivers with decreasing annual sediment transport and stable runoff; 2) rivers with both decreasing annual sediment transport and runoff and 3) rivers with greatly reduced annual sediment transport and decreasing annual runoff. The results indicate that, in all southern rivers (to the south of the Huaihe River including the Huaihe River), there has been little change in average annual runoff but a dramatic decrease in annual sediment transport. In the northern rivers, however, both the annual sediment yield and the runoff show significant evidence of reduction. To further investigate the recent changes in annual runoff and sediment transport, the short-term observation data from these 10 gauging stations in the recent 10 years have been assessed. Results show that both the annual sediment transport and the runoff have decreased significantly in the northern rivers in the past 10 years. Using the Yellow River at the Lijin Station as an example, the average annual runoff for the last 10 years is only 1/3 of the long term average value and the average annual sediment yield of the last 10 years is only 1/4 of the long term average value. More unusually, in the Yongding River the annual sediment yield has approached zero and the runoff has decreased significantly. In addition, the impacts of human activities on the changes in both runoff and sediment transport have been discussed. [Copyright &y& Elsevier]

Abstract: Soil erosion is one of the key concerns in land use management for the Loess Plateau of the Yellow River, where serious soil loss is the root cause of environmental and ecological degradation of the basin. In this paper, a physically-based, distributed-parameter, and continuous erosion prediction model at the river basin scale was developed with the aim of assisting in developing better land use management strategies. The framework, the major supporting techniques, and the typical erosion processes are described. The physical processes of sediment yield and transport in the Loess Plateau are divided into three sub-processes, including the runoff and sediment yield on hillslopes, gravitational erosion in gullies, and hyperconcentrated flow routing in channels. For each sub-process, a physically-based simulation model was developed and embedded into the whole model system. The model system was applied to simulate the runoff and sediment yield in several typical years in the coarse sediment source area of the Loess Plateau, and the simulated results were in reasonably good agreement with the measured values. [Copyright &y& Elsevier]

This paper presents the impacts of frazil ice jams on the variation in water level at the Hequ Reach of the Yellow River in China. Based on both field observations and experimental studies, it is found that both the evolution of frazil ice jams and the associated variation in water level depend upon an interesting interaction between hydraulic variables during the ice-jammed period. In particular, the critical Froude number governing the formation of river ice jams and their upstream propagation is about 0.09. The water level during ice-jammed periods depends not only on the slope of the water surface and the water level under open-water conditions with the same discharge, but also on the length of the ice jam and the ice concentration in the water. Moreover, the field investigations show that the thickness of river ice strongly influences the variation in water level during ice-jammed periods. Empirical relationships are derived to quantify the relationship between the highest water level during ice periods and related physical parameters. To confirm the field results, and to explore the influence of ice discharge on the variation in water level, experimental studies were also conducted. These results confirm that the ice concentration plays a key role in the variation in water level and the jam thickness. Given the complexity of the jamming processes, surprisingly good agreement is observed between field and experimental investigations. [ABSTRACT FROM AUTHOR]

The South Yellow Sea is an important sink for sediments delivered by the Yellow and Yangtze rivers in East Asia. We conducted a high‐resolution geochemical analysis on the bulk sediments retrieved from a marine drill core (CSDP‐1) using the method of X‐ray fluorescence (XRF). Our results show large geochemical variations along the core. As demonstrated by linear correlations along with the Al‐Si link in a compositional principal component analysis (PCA), the variations in elemental ratios among Al, K, Zr, Ba, and Si are primarily controlled by sediment sorting effects. A closer examination indicates a gradual shift of sediment provenance from the Yangtze to the Yellow River catchment in the core. With the help of a fuzzy c‐means cluster analysis on elemental ratios of Al/Si, Al/Ti, K/Si as well as the chemical index of alteration (CIA), the timing of a major provenance change in the core is narrowed down to 1.5–1.7 Ma. This timing corresponds to a major seismic and sedimentary boundary (T2) in the Yellow Sea Basin and coincides with the onset of fluvial terrace deposition and incision in the middle and upper reaches of the Yellow River. As a result, we argue that the major provenance change derived from geochemical variations in the Yellow Sea sedimentary basin can be linked with the integration of the modern Yellow River. The provenance change is likely caused by a coupling between regional tectonic deformation and the Asian summer monsoon enhancement in the early Pleistocene. Plain Language Summary: Located in the East Asia continental margin, the Yellow Sea is an important place where sediment carried by the Yellow River and the Yangtze River, two largest rivers in the world, is deposited. By studying a ∼300‐m‐long drill core (CSDP‐1) in the sea, we attempt to reveal the integration history of the modern Yellow River. What we found is during the Early Pleistocene, approximately from 1.5 to 1.7 Ma, there were significant changes in sediment's chemical features. We interpreted that the changes may represent a sediment source transition from one dominated by the Yangtze River to one by the Yellow River. We conclude that the integration of the modern Yellow River is due to tectonic activity and climate change that happened in the upper and middle reaches during the Early Pleistocene. Key Points: Geochemical variations of sediment records in the South Yellow Sea have been primarily influenced by sediment sorting effectsThe provenance analysis indicates that the integration of the modern Yellow River occurred at 1.5–1.7 MaWe propose different sediment response scenarios in the South Yellow Sea to changes in sediment provenance and sea level since the Late Pliocene [ABSTRACT FROM AUTHOR]

Abstract: This paper is to highlight the threatening of climate change on the water shortage problem in North China, a semi-arid and arid area. Observations show that the runoff of the major rivers is decreasing dramatically especially in the lower reaches where water ishighly demanded. Most noticeable are the dry-outs of the Yellow River, the so-called ‘mother river of China’.Water scarcity would be the most front challenge for the society and economy in China, especially the urban area with extremely high population density. The government already paid attention to the deepening of the underground water level at Beijing. Sustainable water resource management should the top priority for the local community to adapt to climate change. Studies show that human activities heavily impact on the local climate and environment in China and a dramatics amount of clean water is wasted or polluted. [Copyright &y& Elsevier]

The lower Yellow River channel was maintained by artificial levees between 1580 and 1849. During this period, 280 levee breaches occurred. To estimate sediment storage on the floodplains outside the levees, a regression model with a decadal time step was developed to calculate the outflow ratio for the years when levee breaching occurred. Uncertainty analysis was used to identify the likely outflow ratio. Key variables of the model include annual water discharge, a proxy for levee conditions, and potential bankfull discharge of the channel before flood season. Uncertainty analysis reveals an outflow ratio of 0.35–0.56. We estimate that during this period, 18.8–30.1% of the total ~312 Gt of sediment load was deposited on the floodplains outside the levees. Human‐accelerated erosion in the Loess Plateau caused a 4‐fold increase in sediment delivery to the lower Yellow River, which could not be accommodated by channel morphodynamic changes. As a result, 21.2–27.5% of the total sediment load was deposited within the levees, creating a super‐elevated channel bed that facilitated an uncommonly high breach outflow ratio. Hence, the factor of a large super‐elevation relative to the mean main channel depth should be considered when designing diversions to restore floodplains. © 2018 John Wiley & Sons, Ltd. Around 24% of the sediment was deposited in the channel belt and floodplains within levees, 19–30% was trapped in the floodplains outside the levees, and the rest was delivered to the delta area. Human‐accelerated erosion in the Loess Plateau caused a super‐elevated channel bed on the lower river, which favors sediment trapping in the floodplains outside the levees. [ABSTRACT FROM AUTHOR]

The source region of the Yellow River, located in the northeastern part of the Qinghai-Tibetan Plateau, is the typical environmentally fragile region of Chinese eco-environment. As the important water source supplying area of Yellow River, the source region is known as “plateau’s water tower”. There inhabit large quantities of rare wild animals. In this study, based on land ecological classification and field investigation, we used landsat images obtained in 2000 and 2015 to establish databases. From spatial distribution pattern variations and type transformation trend, the spatial changes and dynamic transfers of landscape ecotypes in the source region were analysed by using the analytical methods of landscape ecological spatial patterns. Results show that the unique natural conditions of the source region are more harsh and fragile. There have been phenomena of grasslands deterioration, desertification and wetlands shrinking, and water yield in the upper reaches of the Yellow River has been decreasing in recent years. In the source region, the serious eco-environmental problems have been caused by climate changes, rodent damages and human activities. [ABSTRACT FROM AUTHOR]

In this study, adsorption performance of polyvinyl alcohol (PVA) onto sediments of Yellow River was systematically investigated. Results showed that the sediments could effectively adsorb PVA so as to decrease its dissolved amount in the natural water. Kinetic experiments indicated that a rather rapid uptake of PVA occurred and the removal percentage could reach 60.2% by 24 h. Non-linear fitting method succeeded in discerning that both Toth and Koble-Corrigan models best fitted the experimental data, indicating the possible mono layer and physical adsorption of PVA on the sediments. Langmuir isotherm model also simulated the adsorption isotherm data better, and at 288 K, the maximum adsorption capacity of 356.56 mg/g for PVA uptake was obtained by Langmuir isotherm model. Both, the increase of temperature and solution pH values, would reduce the uptake of PVA. At the same time, the co-existing anions could inhibit the uptake of PVA to some extent. This research would be useful in the risk assessment and subsequent treatment and utilization of the Yellow River. It could also be a reference for other pollution adsorption performances onto the sediments in different rivers. [ABSTRACT FROM AUTHOR]

Abstract: The braiding intensity and dynamics in large braiding rivers are well known to depend on peak discharges, but the response in braiding and channel–floodplain transformations to changes in discharge regime are poorly known. This modelling study addresses the morphodynamic effects of increasing annual peak discharges in braiding rivers. The study site is a braiding reach of the Upper Yellow River. We estimated the effects on the larger‐scale channel pattern, and on the smaller‐scale bars, channel branches and floodplains. Furthermore, we determined the sensitivity of the channel pattern to model input parameters. The results showed that the dominant effect of a higher peak discharge is the development of chute channels on the floodplains, formed by connecting head‐cut channels and avulsive channels. Widening of the main channel by bank erosion was found to be less dominant. In addition, sedimentation on the bars and floodplains increased with increasing peak discharge. The model results also showed that the modelled channel pattern is especially sensitive to parametrization of the bed slope effect, whereas the effect of median grain size was found to be relatively small. Copyright © 2018 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Channel variations of the Inner Mongolian reach in the upper Yellow River are very complicated because of diversity of channel patterns, intense changes in water and sediment, and enhanced human activities in the last decades. It is important to examine the channel migration rates in this river reach. Based on channel planform changes at 236 digital channel cross-sections, the present study estimated the channel migration rates in terms of mid-channel line shift at the digital channel cross-sections during the periods 1975-1990, 1990-2000, 2000-2006, 2006-2010, and 2010-2011. The results show that the average channel migration rate for the whole river reach is 5.0, 7.9, −5.9, 8.6, and −1.0 m in the five different periods, respectively. In both directions to the right and to the left, the highest channel migration rate was always observed in the meandering channels, while the lowest channel migration rate was in the whole Inner Mongolian reach except the Sanhuhekou-Zhaojunfen (S-Z) sub-reach. The temporal variation of channel migration rate was mainly controlled by changing sediment concentration in river flow, while the spatial variation along the straight, braided, and meandering channel reaches was largely affected by material differences of channel banks as reflected by different channel patterns. With the highest average lateral migration rate to the left bank, the meandering channel reach is extremely vulnerable to lateral migration and needs to be protected with engineering practices, because a large population and wide farmland are located on its left floodplain. [ABSTRACT FROM AUTHOR]

Bohai Sea is one of the most intensively exploited region in the world and its environment has been severely impacted by the extensive human activities. The Yellow River is the most important river which connects with the Bohai Sea. Therefore, this study focused on analyzing heavy metals (HMs) in 21 surface sediment samples collected from the Yellow River, China. Sequential extraction procedure (SEP), proposed by the Community Bureau of Reference (BCR), was applied in the present study to determine the concentration and fractionation characteristics of these HMs. The aim of this study was to investigate the spatial distribution, fractionation, risk assessment, and sources of HMs, including copper (Cu), zinc (Zn), lead (Pb), chromium (Cr), iron (Fe), manganese (Mn), and nickel (Ni). The results obtained from this research will play a significant role in understanding the migration, transformation, and accumulation of HMs for future research in study area. Results of fractionation revealed that most of the HMs in the study area mainly existed in residual fraction; however, Mn mostly existed in exchangeable fraction. A high percentage of reducible fractions was found for Cu and Pb. The mean contamination factor (C) values indicated that Pb was the highest. It was >1 and showed moderate contamination, followed by Cr, Cu, Mn, Ni, and Zn, had <1 and indicated low contamination. Among studied HMs Pb had higher enrichment factor (EF) as compared to others. Significant positive correlations within all studied HMs and principal component analysis (PCA) results indicated their common sources, however, Pb showed the different contamination sources. The total contents of HMs in sediment were compared with the threshold effect level (TEL) and probable effect level (PEL) sediment quality guideline (TEL/PEL-based SQGs) values for trace metals in sediment, as well as literature reported data for comparative purposes, which indicated that the selected river in present study is not severe. [ABSTRACT FROM AUTHOR]

Distribution of five heavy metals (Cr, Pb, Cd, Cu, and Zn) and some physicochemical variables were studied from ten sites (S1-S10) in filtered water, suspended particles, and sediment samples from Gansu Province, Ningxia, and Inner Mongolia Autonomous Regions of the Yellow River in Northern China. The results showed that heavy metal concentrations in filtered water were relatively lower, while they were higher and approximated in suspended particles and sediment samples. Metal chemical fractions showed that high proportions of Cd were found in the exchangeable fractions, while others likely to be existed in lithology. Heavy metal pollution index (HPI) indicated that the quality of filtered water was relatively better, and the potential ecological risk index (PERI) revealed that only Cd has the higher ecological risk in suspended particles and sediment samples, which is accordance with the results obtained by the chemical fractions analysis; at the same time, the higher ecological risks existed in S3, S6, S9, and S10 in suspended particles and sediment samples due to the waste emission of a variety of industries. Results of cluster analysis (CA) indicated that contamination sources in the sediment samples were from both natural processes and anthropogenic activities. [ABSTRACT FROM AUTHOR]

Samples were collected monthly from January to December in 2010, and daily observations were made during the water-sediment regulation event in June-July 2010. Sequential extractions were applied to determine the forms of P in different particle-size fractions and to assess the potential bioavailability of particulate phosphorus (PP). The results indicated that exchangeable phosphorus, organic phosphorus, authigenic phosphorus, and refractory phosphorus increased with the decreasing of particulate size; conversely, detrital phosphorus decreased with the decreasing of particulate size. The content of bioavailable particulate phosphorus (BAPP) varied greatly in different sizes of particles. In general, the smaller the particle size, the higher the content of bioavailable phosphorus and its proportion in total phosphorous was found in these particles. Hydrological forcing controlled the variability in the major P phases found in the suspended sediments via changes in the sources and the particle grain-size distribution. The variation of particle sizes can be attributed also to different total suspended sediment (TSS) sources. Water-sediment regulation (WSR) mobilized only particulate matter from the riverbed, while during the rainstorm soil erosion and runoff were the main source. The BAPP fluxes associated with the 'truly suspended' fraction was approximately 200 times larger than the dissolved inorganic phosphorus (DIP) flux. Thus, the transfer of fine particles to the open sea is most probably accompanied by BAPP release to the DIP and can support greater primary and secondary production. [ABSTRACT FROM AUTHOR]

The Yellow River is an important source of sediment flux to oceans in the world, and approximately 90% of the sediment originates from the middle Yellow River, an area with known high rates of soil erosion and sediment delivery. Trends and interannual variations in sediment discharge have considerable implications for reservoir operation and river management of the lower Yellow River. The annual sediment discharge of four main stream stations and ten tributary stations was used to show the spatiotemporal variation in sediment yield and to quantify the relative contribution of precipitation change and human activities, especially the influence of vegetation restoration with implementation of the Grain for Green Project (GGP) in 1999. The Mann-Kendall and Pettitt tests were used to detect the abrupt change in sediment discharge since the 1950s. The annual sediment yield of the middle Yellow River has shown a significant downward trend, decreasing by an order of magnitude in the last decade (2000-2010) compared with the 1950s. Annual sediment yield was reduced by 95.5% from 3,887.0 t ⋅ km-2 ⋅ year-1 in the 1950s to 174.7 t ⋅ km-2 ⋅ year-1 in the 2000s. The eastern part of the middle Yellow River basin showed the most significant decrease, with sediment yield decreasing up to 90% in the 2000s compared with the 1950s. Annual precipitation decreased by 7.3% in the periods 1980-2010 and 1959-1979. Human activities and precipitation explain 83.6 and 16.4% of the total reduction in sediment yield, respectively, using the double mass curve method. Annual sediment discharge decreased by 597 x 106 t ⋅ year-1--from 660 x 106 in 1980-1999 to 63 x 106 in 2000-2010. Sediment deposition along the Longmen- Huayuankou section amounted to 120 x 106 t ⋅ year-1 during 1980-1999 and 229 x 106 t ⋅ year-1 during 2000-2010 based on mass balance. The additional 109 x 106 t ⋅ year-1 of sediment was trapped following completion of the Xiaolangdi Reservoir in the Longmen- Huayuankou section. This explains 18.3% of the sediment reduction in the 2000s. Soil conservation practices have further reduced sediment discharge by 253 x 106 t ⋅ year-1, which explains about 42.4% of the decrease (597 x 106) during 2000-2010. A reduction of approximately 235 x 106 t ⋅ year-1 occurred because of vegetation restoration driven by the Grain for Green Project, which accounted for 39.4% of the total reduction (597 x 106 t ⋅ year-1) in the last decade compared to 1980-1999. [ABSTRACT FROM AUTHOR]

The concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) in water, suspended particulate matters (SPMs), and sediments in the Lanzhou reach of the Yellow River were investigated in this study. The total PAH concentrations ranged from 548 to 2598 ng/L in water, 1502 to 11,562 ng/g in SPMs, and 181 to 1583 ng/g in sediments. The compositions of PAHs showed that 2- to 3-ring PAHs were abundant in water, 2- to 4-ring PAHs were predominant in SPMs, and 2- to 5-ring PAHs were abundant in sediments. The spatial distribution of PAHs was site-specific and PAHs varied at different sampling locations. The diagnostic ratio analysis indicated that the PAHs mainly had a pyrolytic source. The ecological risk assessment showed that the ecosystem risk of PAHs was low in the Lanzhou reach of the Yellow River. [ABSTRACT FROM AUTHOR]

Frequent natural hazards cause huge damage to human life and society in the mountainous regions along the eastern rim of the Tibetan Plateau. A massive landslide damming event has been reported in the Jishixia Gorge on the upper Yellow River as it emerges from the NE Tibetan Plateau. It was speculated that a breach of the dammed lake might have resulted in a super flood disaster that ruined the major Neolithic settlement at Lajia (4.20–3.95 ka BP) within the Guanting Basin that is located in the downstream. However, our detailed investigations along the Jishixia Gorge and Guanting Basin indicate that the dammed lake became shallower and desiccated gradually rather than breaching suddenly. The Yellow River has cut into the dammed lake deposits forming well-exposed profiles on the riverbanks. The dammed lake deposits are considered to provide an accurate natural record of the life-span of the dammed lake. Optically Stimulated Luminescence (OSL) dating was carried out on a series of eight samples taken from the profile. The OSL ages of the dammed lake deposits fall within the range of 8.25 ± 0.39 to 5.65 ± 0.21 ka at the Yisiri site about 2.5 km upstream of the landslide dam. These results indicate that the massive landslide damming event and the corresponding dammed lake occurred at 8.25 ka in the early Holocene. The dammed lake existed for about 2600 years and desiccated gradually and disappeared at 5.65 ka because the landslide dam was dissected slowly by the Yellow River. This means that the landslide dammed lake on the Yellow River disappeared about 1700 years before the Neolithic settlement at Lajia became ruins. The landslide damming event in the Jishixia Gorge is not related to the prehistorical catastrophic disasters that overcame the Lajia settlement within the Guanting Basin. [ABSTRACT FROM AUTHOR]

Multifractal detrended fluctuation analysis (MFDFA) can provide information about inner regularity, randomness and long-range correlation of time series, promoting the knowledge of their evolution regularity. The MFDFA are applied to detect long-range correlations and multifractal behavior of streamflow series at four hydrological stations (Toudaoguai, Longmen, Huangfu and Ganguyi) in the main channel and tributaries of the Yellow River. The results showed that there was one crossover point in the log-log curve of the fluctuation function Fq(s) versus s. The location for the crossover point is approximately one year, implying an unchanged annual periodicity within the streamflow variations. The annual periodical feature of streamflow was removed by using seasonal trend decomposition based on locally weighted regression (STL). All the decomposed streamflow series were characterized by long-term persistence in the study areas. Strong dependence of the generalized Hurst exponent h(q) on q exhibited multifractal behavior in streamflow time series at four stations in the Yellow River basin. The reduction of dependence of h(q) on q for shuffled time series showed that the multifractality of streamflow series was responsible for the correlation properties, as well as the probability density function of the streamflow series. [ABSTRACT FROM AUTHOR]