RESEARCHES ON ENVIRONMENTAL CHANGES OF THE YELLOW RIVER BASIN AND LAWS OF WATER AND SEDIMENT TRANSPORTATION

The major project 'Researches on the environmental changes of the Yellow River Basin and laws of water and sediment transponaion' wasmanaged jointly by the Institute of Geography of Chinese Academy of Sciences(CAS) and State Planning Commission with the Yellow River ConservancyCommission of Ministry of Water Conservancy of China covering the period of July, 1988-December, 1992. All of the anticipated objectives of the project had been completely reached, and research results of the project were checkedand accepted in July, 1993 in Beijing. The project is charactenzed by thecomprehensiveness in research with systematic and all-around conent throughclosely combining environmotal changes with water and sedimenttransportation in the Yellow River basin, and giving full play to the superiority of the cooperation of multiple disciplines and units.A series of major problemswere well replied in the end. Besides studying some problems of the moment,some basic researches on the prosped of reducing sediments delivered into theYellow River after 2000, the ways to prolonging the lifetime of the current lowerYellow River channel, the program of comprehensive management and development of the drainage basin, etc., were carried out. Moreover, the projecthas outstanding features comparing with other researches on the large rivers inChina, and is uncommon in the field of researches on rivers all over the world.

Sediment transport in the Luanhe River delta:grain size trend analysis

Sediment grain size in the deltaic environment of the Luanhe River(LR),Liaoning,China,contains sediment transport pathway information useful in elucidating the shoreline change and fluvialmarine interaction.In this study,we utilized numerical partitioning of the sedimentary components and geostatistical grain size trend analysis(GSTA)to define the sediment transport pattern in the Luanhe River delta(LRD)and interpolated the sediment transport pattern using content changes of end numbers(EM).EM1(the mean grain size 7.12Ф,fine silt),EM2(2.37Ф,fine sand),and EM3(1.27Ф,medium sand)components were identified by the numerical partitioning by GSTA.Kriging interpolation method was used to interpolate the parameters of the grain size for the regular grid,and the interpolation radius was 0.015 decimal degree.We chose 0.09 decimal degree as the characteristic distance for GSTA in the semivariogram model using the geostatistical method.The FB(-)case(finer,better sorted and more negatively skewed)was adopted in GSTA for its satisfaction in the Global Moran’s I test.The result of the GSTA shows that the sediments in the south barriers(SBs)were transported to the southwest of the study area.The sediments in the north,in the SE direction of sediment transport trend from the river mouth,indicated that the sediments in the north of the study area were transported from the LR to the northern beaches,and to the south and east of the study area.The sediment transport trend that simplified by GSTA as the FB(-)case was approved by the content changes of sedimentary components(i.e.EM1,EM2,and EM3).In addition,the turbulent jet diffusion pattern indicated that the coarse sediments(EM3)were delivered by LR during the flood season,and the EM2 and EM1 were from wave and tide,respectively.

Numerical simulations of flow and sediment transport within the Ning-Meng reach of the Yellow River,northern China

Effective management of a river reach requires a sound understanding of flow and sediment transport generated by varying natural and artificial runoff conditions. Flow and sediment transport within the Ning-Meng reach of the Yellow River（NMRYR）, northern China are controlled by a complex set of factors/processes, mainly including four sets of factors：（1） aeolian sediments from deserts bordering the main stream;（2） inflow of water and sediment from numerous tributaries;（3） impoundment of water by reservoir/hydro-junction; and（4） complex diversion and return of irrigation water. In this study, the 1-D flow ＆ sediment transport model developed by the Yellow River Institute of Hydraulic Research was used to simulate the flow and sediment transport within the NMRYR from 2001 to 2012. All four sets of factors that primarily control the flow and sediment transport mentioned above were considered in this model. Compared to the measured data collected from the hydrological stations along the NMRYR, the simulated flow and sediment transport values were generally acceptable, with relative mean deviation between measured and simulated values of 〈15%. However, simulated sediment concentration and siltation values within two sub-reaches（i.e., Qingtongxia Reservoir to Bayan Gol Hydrological Station and Bayan Gol Hydrological Station to Toudaoguai Hydrological Station） for some periods exhibited relatively large errors（the relative mean deviations between measured and simulated values of 18% and 25%, respectively）. These errors are presumably related to the inability to accurately determine the quantity of aeolian sediment influx to the river reach and the inflow of water from the ten ephemeral tributaries. This study may provide some valuable insights into the numerical simulations of flow and sediment transport in large watersheds and also provide a useful model for the effective management of the NMRYR.

Sediment Transport Capacity Under the River–Tide Interaction in the Changjiang Estuary

Sediment transport capacity is a fundamental parameter in sediment transport theory and its accurate calculation is important from both theoretical and engineering viewpoints. The capacity of sediment transport has been studied extensively by many researchers in the last decades. Nevertheless, the underlying mechanism behind sediment transport capacity in estuaries remains poorly understood. The current study aims to explore the impact of the river–tide interaction on sediment transport and establish a formula of sediment transport capacity under the river–tide interaction. The impact of the river–tide interaction on the hydrodynamics and sediment dynamics in the Changjiang Estuary was analyzed, a practical method for describing the variation in tide-runoff ratio was established,and a formula of sediment transport capacity considering the impact of river–tide interaction was proposed by introducing the tide-runoff ratio. The new method bridged the gap between two well-known sediment transport capacity methods by considering the variation in the index a for the gravitational term and overcomes the drawback of distinguishing flood/dry season or spring/ebb tide in the calculation of estuarine sediment transport. A large amount of flow and sediment data obtained from the Changjiang Estuary were collected to verify the proposed formula. The effect of salt-fresh water mixture and the morphological evolution on sediment transport capacity of the Changjiang Estuary were discussed.

Diagnostic experiments for transport mechanisms of suspended sediment discharged from the Yellow River in the Bohai Sea

Five diagnostic experiments with a 3D baroclinic hydrodynamic and sediment transport model ECOMSED in couple with the third generation wave model SWAN and the Grant-Madsen bottom boundary layer model driven by the monthly sediment load of the Yellow River, were conducted to separately diagnose effects of different hydrodynamic factors on transport of suspended sediment discharged from the Yellow River in the Bohai Sea. Both transport and spatio-temporal distribution of suspended sediment concentration in the Bohai Sea were numerially simulated. It could be from the Yellow River cannot be delivered in concluded that suspended sediment discharged long distance under the condition of tidal current. Almost all of sediments from the Yellow River are deposited outside the delta under the condition of wind-driven current, and only very small of them are transported faraway. On the basis of wind forcing, sediments from the Yellow River are mainly transported north-northwestward, and others which are first delivered to the Laizhou Bay are continuously moved northward. An obvious 3D structure characteristic of sediment transport is produced in the wind-driven and tide-induced residual circulation condition. Transport patterns at all layers are generally consistent with circulation structure, but there is apparent deviation between the depth-averaged sediment flux and the circulation structure. The phase of temporal variation of sediment concentration is consistent with that of the bottom shear stress, both of which are proved to have a ten-day cycle in wave and current condition.

Equilibrium sediment transport in lower Yellow River during later sediment-retaining period of Xiaolangdi Reservoir

The Xiaolangdi Reservoir has entered the later sediment-retaining period, and new sediment transport phenomena and channel re-estab- lishing behaviors are appearing. A physical model test was used to forecast the scouring and silting trends of the lower Yellow River. Based on water and sediment data from the lower Yellow River during the period from 1960 to 2012, and using a statistical method, this paper analyzed the sediment transport in sediment-laden flows with different discharges and sediment concentrations in the lower Yellow River. The results show that rational water-sediment regulation is necessary to avoid silting in the later sediment-retaining period. The combination of 3 000 m^3/s 〈 Q 〈 4 000 m^3/s and 20 kg/m^3 〈 S 〈 60 kg/m^3 （where Q is the discharge and S is the sediment concentration） at the Huayuankou section is considered an optimal combination for equilibrium sediment transport in the lower Yellow River over a long period of time.

Hydrodynamic Characteristics and Sediment Transport of A Tidal River Under Influence of Wading Engineering Groups

By taking the Yong River for example in this paper, based on the multiple measured data during 1957 to 2009, the change process of runoff, tide feature, tidal wave, tidal influx and sediment transport are analyzed. Then a mathematical model is used to reveal the influence mechanism on hydrodynamic characteristics and sediment transport of the wading engineering groups such as a tide gate, a breakwater, reservoirs, bridges and wharves, which were built in different periods. The results showed the hydrodynamic characteristics and sediment transport of the Yong River changed obviously due to the wading engineering groups. The tide gate induced deformation of the tidal wave, obvious reduction of the tidal influx and weakness of the tidal dynamic, decrease of the sediment yield of flood and ebb tide and channel deposition. The breakwater blocked estuarine entrances, resulting in the change of the tidal current and the reduction of the tidal influx in the estuarine area. The large-scale reservoirs gradually made the decrease of the Yong River runoff. The bridge and wharf groups took up cross-section areas, the cumulative affection of which caused the increase of tidal level in the tidal river.

Numerical Study on Seasonal Transportation of the Suspended Sediments in the Modern Yellow River Mouth Effected by the Artificial Water and Sediment Regulation

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.

Scale effects of eroded sediment transport in Wujiang River Basin, Guizhou Province, China

In recent years, research on spatial scale and scale transformation of eroded sediment transport has become a forefront field in current soil erosion research, but there are very few studies on the scale effect problem in Karst regions of China. Here we quantitatively extracted five main factors influencing soil erosion, namely rainfall erosivity, soil erodibility, vegetative cover and management, soil and water conservation, and slope length and steepness. Regression relations were built between these factors and also the sediment transport modulus and drainage area, so as to initially analyze and discuss scale effects on sediment transport in the Wujiang River Basin(WRB). The size and extent of soil erosion influencing factors in the WRB were gauged from: Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital Elevation Model(ASTER GDEM), precipitation data, land use, soil type and Normalized Difference Vegetation Index(NDVI) data from Global Inventory Modeling and Mapping Studies(GIMMS) or Advanced Very High Resolution Radiometer(AVHRR), and observed data from hydrometric stations. We find that scaling effects exist between the sediment transport modulus and the drainage area. Scaling effects are expressed after logarithmic transformation by a quadratic function regression relationship where the sediment transport modulus increases before decreasing, alongside changes in the drainage area. Among the five factors influencing soil erosion, slope length and steepness increases first and then decreases, alongside changes in the drainage area, and are the main factors determining the relationship between sediment transport modulus and drainage area. To eliminate the influence of scale effects on our results, we mapped the sediment yield modulus of the entire WRB, adopting a 1 000 km^2 standard area with a smaller fitting error for all sub-basins, and using the common Kriging interpolation method.

Sediment discharge of the Yellow River, China: past, present and future——A synthesis

The Yellow River cut through Sanmenxia Gorge and discharged into the sea via the North China Plain in 150 ka BP; since then, around 86 000 × 108 t sediment has been transported passing Sanmenxia Gorge. Based on land use and land cover changes in Loess Plateau and other available evidence, an estimate of the Yellow River sediment budget is presented here： about 72% of the sedimentary material was trapped in the North China Plain and the remainder（i.e., 26%） escaped to the sea. At the present stage, 〈 0.2×108 t/a suspended sediment of the Yellow River enter the northern Yellow Sea. The transport pattern is determined mainly by the shelf current system. Annually 0.2×108–0.3×108 t of suspended particles are carried to the East China Sea; the materials are derived mainly from coastal and subaqueous delta erosion associated with the abandoned Yellow River on the Jiangsu coast. Since 1972, the lower Yellow River started to have a situation of continuous no-flow. During 1996–2000, the annual water flow and sediment discharge are only 19%, as compared with normal years（i.e., average for 1950–1979）. In response to global warming and increase of water diversion from the Yellow River for industrial and urban use, the sediment flux of the Yellow River to the sea will most likely remain small in the next two to three decades.

Distributional characteristics of grain sizes of surface sediments in the Zhujiang River Estuary

Distributions of the parameters of sedimentary grain sizes and their correlations were studied to trace the sources of silts and their movement trends in the Zhujiang River Estuary based on the analyses of grain sizes from more than 1080 sedimentary samples. The distributions of the median diameter, public value, quartile deviation, and skewness of sediments were complex in the Zhuiiang River Estuary mainly because of the impact of the matter source regions, distances from the source regions, and hydrodynamic conditions, such as waves, tidal currents, and coastal currents. Analyses of the parameters of the grain sizes for the various types of sediments showed that the distributions of the surface sediments in the Zhujiang River Estuary were controlled by many factors. Their matter sources were mainly the sediments discharged from the runoffs and ebb tidal currents, and from the open sea. The sediments mainly moved by suspension movement. The silts formed a large area of sediments with suspended fine silts in the Zhujiang River Estuary by internal adjustment transportation in the area, and moved toward the western coast of the Zhujiang River Estuary under the effect of Coriolis forces and coastal currents.

Modeling of suspended sediment by coupled wave-current model in the Zhujiang(Pearl) River Estuary

A three-dimensional wave-current-sediment coupled numerical model is developed to understand the sediment transport dynamics in the Zhujiang(Pearl)River Estuary(ZRE),China.The model results are in good agreement with observed data,and statistics show good model skill scores.Numerical studies are conducted to assess the scenarios of suspended sediment in the ZRE under the effects of different forcing(river discharges,waves,and winds).The model results indicate that the estuarine gravitational circulation plays an important role in the development of estuarine turbidity maximum in the ZRE,particularly during neap tides.The increased river discharge can result in a seaward sediment transport.The suspended sediment concentration(SSC)in the bottom increases with both wave bottom orbital velocity and wave height.Because of the shallow water depth,the effect of waves on sediment in the west shoal is greater than that in the east channel.The southwesterly wind-induced wave affects the SSC more than those resulting from the northeasterly wind,while the northeasterly wind-driven circulation has a slightly greater influence on the SSC than that of the southwesterly wind.However,a steady southwesterly wind condition favors the increase of the SSC in the Lingding Bay more so than a steady northeasterly wind condition.If the other forcings are same,the averaged SSC under a steady southwesterly wind condition is about 1.1 times that resulting from a steady northeasterly wind.

Assessment of soil erosion in a tropical mountain river basin of the southern Western Ghats,India using RUSLE and GIS

Revised Universal Soil Loss Equation(RUSLE) model coupled with transport limited sediment delivery(TLSD) function was used to predict the longtime average annual soil loss, and to identify the critical erosion-/deposition-prone areas in a tropical mountain river basin, viz., Muthirapuzha River Basin(MRB; area=271.75 km^2), in the southern Western Ghats, India. Mean gross soil erosion in MRB is 14.36 t ha^(-1) yr^(-1), whereas mean net soil erosion(i.e., gross erosion-deposition) is only 3.60 t ha^(-1) yr^(-1)(i.e., roughly 25% of the gross erosion). Majority of the basin area(~86%) experiences only slight erosion(<5 t ha^(-1) yr^(-1)), and nearly 3% of the area functions as depositional environment for the eroded sediments(e.g., the terraces of stream reaches, the gentle plains as well as the foot slopes of the plateau scarps and the terrain with concordant summits). Although mean gross soil erosion rates in the natural vegetation belts are relatively higher, compared to agriculture, settlement/built-up areas and tea plantation, the sediment transport efficiency in agricultural areas and tea plantation is significantly high,reflecting the role of human activities on accelerated soil erosion. In MRB, on a mean basis, 0.42 t of soil organic carbon(SOC) content is being eroded per hectare annually, and SOC loss from the 4th order subbasins shows considerable differences, mainly due to the spatial variability in the gross soil erosion rates among the sub-basins. The quantitative results, on soil erosion and deposition, modelled using RUSLE and TLSD, are expected to be beneficial while formulating comprehensive land management strategies for reducing the extent of soil degradation in tropical mountain river basins.

Unit stream power,minimum energy dissipation rate,and river engineering

Unit stream power is the most important and dominant parameter for the determination of transport rate of sand,gravel,and hyper-concentrated sediment with wash load.Minimum energy dissipation rate theory,or its simplified minimum unit stream power and minimum stream power theories,can provide engineers the needed theoretical basis for river morphology and river engineering studies.The Generalized Sediment Transport model for Alluvial River Simulation computer mode series have been developed based on the above theories.The computer model series have been successfully applied in many countries.Examples will be used to illustrate the applications of the computer models to solving a wide range of river morphology and river engineering problems.

An Investigation of Stochastic Nature of Bed Load Motion in Chuanjiang River

Bed Load Motion and its transport rate is one of the basic issues in river dynamics.In this paper, the authors discussed the stochastic nature of bed load motion in Chuanjiang River in details.Chungjiang lies in the upstream reach of Yangtze River.Its stochastic nature is shown in the following four aspects.Firstly, even though all the conditions are the same,due to the fluctuation of the flow,the bed load discharge and the location and width of sediment transport belts are different.Secondly,during the ...

Study on the Role of Tidal Currents in the Process of Formation and Development of the Changjiang River Delta

The Changjiang River Delta is a delta of tremendous scale which is formed under the control of tide and tidal currents. The study on the role of tide and tidal currents in the process of formation and development of the Changjiang River Delta can provide a typical example for the ocean-continent interaction process in the east area of our country. The tide and tidal currents in the Bohai Sea, Yellow Sea and East China Sea at the post-glacial transgression maximum are simulated, the sediment transport field in the Paleo-Changjiang River Estuary(PCRE) and its peripheral area at that time is calculated, and the seabed erosion/accretion pattern is obtained according to the divergence of sediment transport rate. The results show that a distinctive wave belly of standing tidal wave existed at the post-glacial transgression maximum and the wave belly lines protruded seawards from the wave belly point in the mouth of the PCRE. Under the wave belly control tidal currents converge to or diverge from the wave

Vectorial Bed load Equations and River Width Dynamic Adjustment Modeling

Based on the analysis of forces acting on non-cohesive sediment particle under non-equilibrium con- dition,a vectorial equation of coarse particle movement on arbitrarily riverbed and the mathematical model used to simulate river width adjust are developed,some flume experiments for the time evolution of straight river channel are done.

Impacts of Dredging on Fluvial Geomorphology in the Jamuna River, Bangladesh

Jamuna, a major braided river in Bangladesh, has an enormous hydrological impact on the surrounding areas and streams. Erosion and sedimentation in the Jamuna river cause a large flow fluctuation and floods round the year. Bangladesh Water Development Board has initiated a pilot capital dredging project in the Jamuna river in 2011-2012, aiming to guide the flow to reduce the risk of failure of the city area and right guide bundh of the Jamuna Bridge. This study explores the long-term role of dredging on river morphology us-ing erosion-sedimentation numerical modeling approaches. Primary data were employed in numerical models to estimate the erosion-sedimentation and compared outputs with the real-time cross-sectional variation at selected sections along the reach during 2012-2013. The analysis suggested that the rate of sedimentation is higher (60% to 80%), where the dredging alignment crosses through the existing sandbar/char. Moreover, a cross-section com-parison revealed that the channel near Sirajganj Hardpoint shifted towards the left (east) bank, and the channel within the study area developed very fast along the right (west) bank. However, satellite image analysis revealed that the major bankline shifting occurred from 2000 to 2010 and the channel shifting was observed from 2014 to 2018 along the reach, mostly, after the construction of some river training works. The variation of the channel per-sistence (40% - 100%) selected part of the study area in the channel inci-dence map, indicating the rapid dynamic behavior of the river morphology. This study showed a good agreement of measured data and simplified em-pirical relationships to predict the long-term morphodynamic behavior of the braided Jamuna river.

1955-2021年期间长江中游枝城至螺山河段与三口洪道水沙输移变化规律

长江与洞庭湖之间存在复杂的江湖水沙交换关系,水沙变化引起江湖冲淤变化,从而对长江中游区域防洪、水资源利用、航运及水生态环境等产生较大影响。本文利用实测资料较为系统地分析了荆江与洞庭湖水沙输移变化规律,结果表明:1955-2021年期间枝城、沙市、螺山站年径流量变化趋势不明显,监利站年径流量增幅为17.4%,三口分流洪道与七里山站均以减少为主;1955-1989年期间枝城与沙市站年输沙量变化趋势不明显,监利站明显增加,三口分流洪道与七里山站明显减少,1990-2021年期间各站均显著减少,其中三峡工程运用后荆江河段(枝城站)、三口分流洪道、洞庭湖出湖及城螺河段年输沙量分别减少90.1%、90.2%、22.5%及76.6%;受水库下泄径流过程改变的影响,荆江河段、荆江三口分流洪道、洞庭湖出湖与城螺河段年内径流过程均呈不同程度的坦化,枯水期平均流量均显著增加,消落期平均流量稍有增加,汛期出现一定程度的减少,蓄水期稍有减少,下泄径流过程坦化以及2006、2011年特枯水年分别引起荆江三口年均分流量减少41.2亿和32.4亿m~3。随着三峡上游水库群陆续建成运用,荆江河段、三口分流洪道、洞庭湖出湖及城螺河段径流量将进一步坦化,由于干流河床泥沙补给逐渐减少,输沙量将进一步减少,预计长江与洞庭湖水沙输移变化规律将基本保持现有变化格局。

Simulation of Artificial Grain Feeding in Order to Reach Dynamical Bed Stabilisation Along the River Rhine

The Wesel-Xanten stretch of the fiver Rhine between km-812.5 and km-821.5 is one of the reaches where strong erosion leads to high maintenance efforts conceming navigability.In order to improve the naviga- tion conditions without aggravating the flood protection,but also ensuring that the ecological system of the river is not damaged,investigations of the morphodynamical processes in connection with artificial grain feeding ac- tivities have to be carried out by Federal Waterways Engineering and Research...