Recent changes in sediment delivery by the Huanghe (Yellow River) to the sea: Causes and environmental implications in its estuary

Wang, Houjie; Bi, Naishuang; Saito, Yoshiki; Wu, Yan; Sun, Xiaoxia; Zhang, Jia; Yang, Zuosheng

doi:10.1016/j.jhydrol.2010.07.030

Cited by 298 publications

(147 citation statements)

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“…6). Afforestation, terraced farming, and the construction of check dams and reservoirs are the major human interventions in this area that have led to increased precipitation retention (Supplementary Table 3), and the consequent reduction of river sediment flux 3,[10][11][12]16 . One of the most effective methods of stabilizing soils and minimizing erosion is to establish perennial vegetation cover 13,17,18 .…”

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Reduced sediment transport in the Yellow River due to anthropogenic changes

et al. 2015

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The erosion, transport and redeposition of sediments shape the Earth's surface, and a ect the structure and function of ecosystems and society 1,2 . The Yellow River was once the world's largest carrier of fluvial sediment, but its sediment load has decreased by approximately 90% over the past 60 years 3 . The decline in sediment load is due to changes in water discharge and sediment concentration, which are both influenced by regional climate change and human activities. Here we use an attribution approach to analyse 60 years of runo and sediment load observations from the traverse of the Yellow River over China's Loess Plateau -the source of nearly 90% of its sediment load. We find that landscape engineering, terracing and the construction of check dams and reservoirs were the primary factors driving reduction in sediment load from the 1970s to 1990s, but large-scale vegetation restoration projects have also reduced soil erosion from the 1990s onwards. We suggest that, as the ability of existing dams and reservoirs to trap sediments declines in the future, erosion rates on the Loess Plateau will increasingly control the Yellow River's sediment load.Change of soil erosion and the resulting river sediment transport are important components of global change, so understanding the mechanisms behind such change is crucial to developing strategic plans for the sustainable management of catchments 4,5 . In recent decades, significant decreasing trends in river sediment loads have been observed in approximately 50% of the world's rivers 6,7 . The benefits and risks of the change in river sediment load largely depend on the baseline load and the scale of the change 8,9 . Hence, it is important to quantify the change of river sediment loads through time, and to understand the drivers and mechanisms behind them 2,5 .The Huang He, or Yellow River (YR) (Fig. 1), was the most sediment-laden river in the world, but its annual sediment load has continually decreased since the 1950s (refs 10-13). The yearly sediment loads at the main gauging stations along the YR, all show significant decreasing trends (p < 0.01) over the past six decades (Fig. 1b). Sediment load increases most suddenly in the middle reach of the river, when crossing the Loess Plateau (LP), between the Toudaoguai gauging station (TDG) (0.07 Gt yr −1 ) and the Tongguan station (TG) (0.63 Gt yr −1 ), and then gradually declines in the lower reach (Fig. 1b, top right inset). The LP is thus the largest sediment source, nearly 90% (refs 3,11) for the YR, and we therefore focus on this part of the river's catchment. A mass budget over the middle reach of the YR can be obtained from the difference of measured sediment flux and water discharge at TG and TDG (Fig. 1). Both the river discharge and sediment load across the LP show significant decreasing trends (−0.25 km 3 yr −2 , p < 0.001; and −0.02 Gt yr −2 , p < 0.001, respectively) over the past six decades, whereas precipitation decreased slightly (−1.2 mm yr −2 , p = 0.015). As Fig. 2a shows two abrupt falls in sed...

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Reduced sediment transport in the Yellow River due to anthropogenic changes

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“…Since 2002, this water-sediment modulated scheme has been conducted in June every year and as a result, a considerable amount of sediment deposited in the Xiaoliangdi Reservoir has been expelled out and the uplifted bed of the lower reach of the Yellow River scoured to a considerable degree (e.g. Wang et al, 2010;Chen et al, 2012;Chu, 2014). Due to the heavy deposition of sediment, the channel bed of the lower reach has become elevated above the adjacent valley floor by some 8 to 12 m over the past 40 years, so this water-sediment modulated scheme helps to reduce the discrepancy in channel and ground elevation (Ma et al, 2012;Chu, 2014).…”

Section: Water Regulation Programmentioning

confidence: 99%

“…Because the YRD has been continuously creating new land since its inception, the significant declines in the water and sediment supply to the delta over the last several decades have aroused considerable concerns for those interested in agriculture and socio-economic development and those concerned with wetland conservation for wildlife (Zhu et al, 2003;Wang et al, 2010;Kuenzer et al, 2014). To address these issues, several studies have estimated the minimum amount of sediment input and/or water supply required before net erosion of the YRD occurs.…”

Section: Critical Water and Sediment Supply For Land Accretionmentioning

confidence: 99%

“…Consequently, the amount of water and sediment delivered to the YRD has reduced and the rate of sedimentation in the estuary slowed greatly, causing significant coastal erosion in many parts of the delta (e.g. Chu et al, 2006;Saito et al, 2007;Wang et al, 2010;Ma et al, 2012;Yu et al, 2013a,b;Chu, 2014;Liu et al, 2014;Zhou et al, 2014). The delta today supports a human population of more than two million who obtain their livelihood from farming, fishing and oilexploiting, so changes to its water and sediment supply and land area can have profound impacts.…”

Section: Introductionmentioning

confidence: 99%

“…Xu (2002) suggested that the effects of both water and sediment supply on the progradation of the YRD need to be determined in an integrated way; however, most studies so far have focused on these parameters separately (e.g. Wang et al, 2006Wang et al, , 2010Cui and Li, 2011;Bi et al, 2014). The lack of an integrated approach makes it difficult to evaluate the combined effects of water and sediment supply on delta progradation.…”

Section: Introductionmentioning

confidence: 99%

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Progradation of the Yellow (Huanghe) River delta in response to the implementation of a basin-scale water regulation program

et al. 2015

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The water and sediment supply to the lower reach and estuary of the Yellow (Huanghe) River have been altered to a very significant degree by the construction of numerous small to large reservoirs and the progressive implementation of water and soil conservation measures across the entire drainage basin since the late 1950s, followed by a basin-scale water regulation program since 2002. There is an urgent need to know how progradation of the Yellow River delta (YRD), an area on which people live and farm, has continued and will continue to respond to these controls. This study examines the changing patterns of water and sediment supply to the YRD over the period of 1950-2013 and, using remote sensing, it evaluates the morphological changes of the delta during 1976-2013. Although both water and sediment input to the delta have been described as declining significantly since the mid 1960s, we show that since 2005 the supply of water has remained at around 20 billion m 3 yr −1 and that for sediment at about 0.13 billion t yr −1 ; water input has been even slightly increasing. The dynamics of extension/shrinking and avulsion in river-mouth channels and accretion/erosion of shorelines is an integrated response to the complex variations in both sediment and water supply. This study develops a quantitative relationship between water and sediment supply and the area of land accretion and it predicts the critical condition for land accretion in the YRD. To ensure that delta land will not be lost, care is needed in the future implementation of the basin-scale water regulation program.

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Hydrodynamic analysis of fully developed turbidity currents over plane beds based on self‐preserving velocity and concentration distributions

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This paper presents a hydrodynamic analysis for the fully developed turbidity currents over a plane bed stemming from the classical three‐equation model (depth‐averaged fluid continuity, sediment continuity, and fluid momentum equations). The streamwise velocity and the concentration distributions preserve self‐similarity characteristics and are expressed as single functions of vertical distance over the turbidity current layer. Using the experimental data of turbidity and salinity currents, the undetermined coefficients and exponents are approximated. The proposed relationships for velocity and concentration distributions exhibit self‐preserving characteristics for turbidity currents. The depth‐averaged velocity, momentum, and energy coefficients are thus obtained using the proposed expression for velocity law. Also, from the expressions for velocity and concentration, the turbulent diffusivity and the Reynolds shear stress distributions are deduced with the aid of the diffusion equation of sediment concentration and the Boussinesq hypothesis. The generalized equation of unsteady nonuniform turbidity current is developed by using the velocity and concentration distributions in the moments of the integral scales over the turbidity current layer. Then, the equation is applied to analyze the gradually varied turbidity currents considering closure relationships for boundary interaction and shear velocity. The streamwise variations of current depth, velocity, concentration, reduced sediment flux, and Richardson number are presented. Further, the self‐accelerating and depositional characteristics of turbidity currents including the transitional feature from erosional to depositional modes are addressed. The effects of the streamwise bed slope are also accounted for in the mathematical derivations. The results obtained from the present model are compared with those from the classical model.

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Recent changes in sediment delivery by the Huanghe (Yellow River) to the sea: Causes and environmental implications in its estuary

Cited by 298 publications

References 27 publications

Reduced sediment transport in the Yellow River due to anthropogenic changes

Reduced sediment transport in the Yellow River due to anthropogenic changes

Progradation of the Yellow (Huanghe) River delta in response to the implementation of a basin-scale water regulation program

Hydrodynamic analysis of fully developed turbidity currents over plane beds based on self‐preserving velocity and concentration distributions

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