Fourth Largest River Research Articles

Effect of hydropower dam flow regulation on salt-water intrusion: São Francisco River, Brazil

The São Francisco River is the fourth largest river in Latin America, and particularly important since it crosses the Brazilian semi-arid region. During the 1960s–90s, a series of dams for hydropower were built in cascade, changing drastically the flow regime. To evaluate the influence of changes in the flow on hydrodynamic processes and saline intrusion in the estuary, a three-dimensional hydrodynamic model was applied to the system. The model was calibrated and validated from hydrodynamic data collected in the estuary. The simulated scenarios of river discharges were Qmin, Q10, Q80 and Qmax (corresponding to 600, 5000, 1200, and 12,000 m3.s−1, respectively), determined from historical river discharge observations. There was an increase in the mixing and a decrease in the river contribution after the installation of dams. The average salinity in the estuarine domain ranged from 0.7 g.kg−1 for intermediate pre-dam discharge to 15.6 g.kg−1 in the lowest discharges after the dam installations. The results of the simulations were used to establish an exponential relationship between fluvial discharge and saline intrusion, which can be used by management agencies to optimize the water quality in catchments for human consumption.

Flood risk assessment at Tundzha river basin, Bulgaria

Tundzha River is the third greatest river in Bulgaria and the largest tributary of the fourth largest river in the country, the Maritsa River. The risks for flood events in the Tundzha River basin was assessed based on the characteristics of the river basin and the main causes of floods as sources and mechanisms. The populated places at the highest risks of flood events were identified. The risk forecasting for the city of Yambol, the largest city on the river’s banks, was also presented in the case of floods with different heights of the wave. It was found that flooding in the Bulgarian side of the Tundzha River basin could be caused mostly by high river water levels due to severe rainfall or the rapid melting of huge amounts of snow.

ГИДРОЛОГИЧЕСКОЕ ОБОСНОВАНИЕ УПРАВЛЕНИЯ ВОДНЫМИ РЕСУРСАМИ В ВЕРХНЕЙ ЧАСТИ БАССЕЙНА ДНЕПРА

The Dnieper river is one of the largest rivers in Europe. It is the fourth largest river in terms of basin area and length after the Volga, Danube and Ural, and the second largest of the rivers that flow into the Black sea, after the Danube. From the point of view of territorial distribution of water resources, the Dnieper basin can be divided into two zones. The first zone includes the Russian and Belarusian parts of the basin, which is a zone of river flow formation. It is characterized by an insufficiently high level of water resources use. The second zone, which is a part of the Ukrainian part of the river basin, is characterized by a small inflow of water from tributaries and a high level of water resources use. Rivers, watercourses of which run through the territory of two or more states, are called as transboundary. Different sections of the same river are used by different states, and the use of water resources and catchment area in the upper reaches of the river will affect the quantitative and qualitative parameters of water downstream. This means that the unified environmental system is divided by a state border and is managed in each individual state at its discretion. This affects the river and surrounding areas. After the collapse of the Soviet Union, the problem of transboundary water bodies became very relevant for Russia. Neighboring countries have faced a number of environmental problems in border territories and transboundary river basins, where environmental problems have persisted and often worsened, but the institutional framework for their effective solution has been lost

Real-time water quality monitoring through Internet of Things and ANOVA-based analysis: a case study on river Krishna

In this paper, an attempt has been made to develop a statistical model based on Internet of Things (IoT) for water quality analysis of river Krishna using different water quality parameters such as pH, conductivity, dissolved oxygen, temperature, biochemical oxygen demand, total dissolved solids and conductivity. These parameters are very important to assess the water quality of the river. The water quality data were collected from six stations of river Krishna in the state of Karnataka. River Krishna is the fourth largest river in India with approximately 1400 km of length and flows from its origin toward Bay of Bengal. In our study, we have considered only stretch of river Krishna flowing in state of Karnataka, i.e., length of about 483 km. In recent years, the mineral-rich river basin is subjected to rapid industrialization, thus polluting the river basin. The river water is bound to get polluted from various pollutants such as the urban waste water, agricultural waste and industrial waste, thus making it unusable for anthropogenic activities. The traditional manual technique that is under use is a very slow process. It requires staff to collect the water samples from the site and take them to the laboratory and then perform the analysis on various water parameters which is costly and time-consuming process. The timely information about water quality is thus unavailable to the people in the river basin area. This creates a perfect opportunity for swift real-time water quality check through analysis of water samples collected from the river Krishna. IoT is one of the ways with which real-time monitoring of water quality of river Krishna can be done in quick time. In this paper, we have emphasized on IoT-based water quality monitoring by applying the statistical analysis for the data collected from the river Krishna. One-way analysis of variance (ANOVA) and two-way ANOVA were applied for the data collected, and found that one-way ANOVA was more effective in carrying out water quality analysis. The hypotheses that are drawn using ANOVA were used for water quality analysis. Further, these analyses can be used to train the IoT system so that it can take the decision whenever there is abnormal change in the reading of any of the water quality parameters.

Brahmaputra river in India: An analytical study with special reference to its erosion.

The complex and unique riverbank erosion characteristics of the Brahmaputra River in India, the fourth largest river in the world in terms of average discharge at the mouth and second only to the Yellow River in China in the amount of sediment transported per unit drainage area, is highlighted with illustrations of the severity of erosion caused at various bank locations. First, the source and the entire course of the river are described. Riverbank erosion mechanisms and existing erosion control measures and their effectiveness in the Assam reach of the Brahmaputra River are described. As part of a joint effort for the first time between U.S. and Indian (local) investigators to understand and find solutions to this mega unique problem of the Brahmaputra River, a set of recommendations, including a phase-wise multiple solutions to the acute and potential riverbank erosion sites along this large river, is forwarded for discussion and getting feed back from international experts.

Dynamics of greenhouse gases (CO<sub>2</sub>, CH<sub>4</sub>, N<sub>2</sub>O) along the Zambezi River and major tributaries, and their importance in the riverine carbon budget

Abstract. Spanning over 3000 km in length and with a catchment of approximately 1.4 million km2, the Zambezi River is the fourth largest river in Africa and the largest flowing into the Indian Ocean from the African continent. We present data on greenhouse gas (GHG: carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O)) concentrations and fluxes, as well as data that allow for characterization of sources and dynamics of carbon pools collected along the Zambezi River, reservoirs and several of its tributaries during 2012 and 2013 and over two climatic seasons (dry and wet) to constrain the interannual variability, seasonality and spatial heterogeneity along the aquatic continuum. All GHG concentrations showed high spatial variability (coefficient of variation: 1.01 for CO2, 2.65 for CH4 and 0.21 for N2O). Overall, there was no unidirectional pattern along the river stretch (i.e., decrease or increase towards the ocean), as the spatial heterogeneity of GHGs appeared to be determined mainly by the connectivity with floodplains and wetlands as well as the presence of man-made structures (reservoirs) and natural barriers (waterfalls, rapids). Highest CO2 and CH4 concentrations in the main channel were found downstream of extensive floodplains/wetlands. Undersaturated CO2 conditions, in contrast, were characteristic of the surface waters of the two large reservoirs along the Zambezi mainstem. N2O concentrations showed the opposite pattern, being lowest downstream of the floodplains and highest in reservoirs. Among tributaries, highest concentrations of both CO2 and CH4 were measured in the Shire River, whereas low values were characteristic of more turbid systems such as the Luangwa and Mazoe rivers. The interannual variability in the Zambezi River was relatively large for both CO2 and CH4, and significantly higher concentrations (up to 2-fold) were measured during wet seasons compared to the dry season. Interannual variability of N2O was less pronounced, but higher values were generally found during the dry season. Overall, both concentrations and fluxes of CO2 and CH4 were well below the median/average values for tropical rivers, streams and reservoirs reported previously in the literature and used for global extrapolations. A first-order mass balance suggests that carbon (C) transport to the ocean represents the major component (59%) of the budget (largely in the form of dissolved inorganic carbon, DIC), while 38% of the total C yield is annually emitted into the atmosphere, mostly as CO2 (98%), and 3% is removed by sedimentation in reservoirs.

Sedimentation in the Outer Hangzhou Bay, China: The Influence of Changjiang Sediment Load

Dai, Z.-j.; Liu, J.T.; Xie H.-l., and Shi, W.-y., 2014. Sedimentation in the outer Hangzhou Bay, China: The influence of Changjiang sediment load.Most estuaries in the world are facing the risk of subsidence due to insufficient sediment supply and relative sea-level rise. In the case of the world's fourth largest river, the Changjiang (aka Yangtze River), its river sediment load has been decreasing sharply, especially since the construction of the Three Gorges Dam. Due to the complexity in the estuarine dynamics, human activities, and the sediment supply, discerning whether the Changjiang Estuary is facing erosion or subsidence is a controversial issue. Immediately south of the mouth of the Changjiang is Hangzhou Bay. On the centennial time scale, accretion on the southern flank of the Changjiang deltaic plain has caused the seaward extension of the north bank of the Qiantang Estuary, leading to the formation of the macrotidal, funnel-shaped Hangzhou Bay. In this study, we used multiyear geographic information system (GIS)–rectified bathymetric charts of Hangzhou Bay for bathymetry and sediment-capacity change analysis. Our major findings show that the outer Hangzhou Bay has gone through the following stages: relatively steady sedimentation (1931–1997), erosional-depositional transition (1997–2002), and rapid erosion (2002–2008) at the rate of 58.5 × 106 m3/y. Our findings also corroborate measurements of suspended sediment discharge at the Datong station in the lower reaches of the Changjiang. Our findings confirm the dependence of the sedimentation in the outer Hangzhou Bay on the sediment supplied by the Changjiang. The severity of the erosion of the outer Hangzhou Bay and the sediment load decrease of the Changjiang might serve as a warning for the impending erosion of the Changjiang Estuary.

Ecological zonation of benthic foraminifera in the lower Guadiana Estuary (southeastern Portugal)

Abstract The present study analyzes the spatial distribution and seasonal distribution of live benthic foraminiferal communities in the estuary of Guadiana, the fourth largest river on the Iberian Peninsula, and establishes, through statistical analysis, their relationships with a series of environmental parameters. Forty-four superficial sediment samples were collected along distance-to-sea and elevation gradients in the winter and summer of 2010. Fifty-three foraminifera species were identified along the intertidal margins of the estuary. Foraminiferal distribution reflected seasonal variation of environmental factors, whose relative importance varied according to species tolerances. Elevation in relation to mean sea level appeared to be the most important parameter controlling foraminiferal distribution, probably because it combines the effects of a series of other variables (i.e. organic matter, sediment texture, pH and temperature). In the highest marsh areas, where environmental conditions approach survival thresholds, only some agglutinated species are able to survive. In the lower intertidal zone, where subaerial exposure is diminished and environmental conditions are generally less variable, more diverse faunas, mainly composed of calcareous species, prevail. During winter, when fluvial discharge peaks, agglutinated species represent more than 80% of the total individuals. In summer, when marine conditions prevail, calcareous species become more competitive, increase their densities and expand into higher marsh zones and estuarine upper reaches. In the estuary, three different foraminiferal assemblages are distinguished: i) Miliammina fusca assemblage, which dominates in unvegetated areas of the lower marsh and tidal flats of the mid-upper estuary; ii) Jadammina macrescens assemblage, which dominates in the highest marsh areas in the lower estuary; and iii) Ammonia aberdoveyensis assemblage, which dominates the areas of low marsh and tidal flats of the lower estuary.

Tsunami Hydrodynamics in the Columbia River

On 11 March 2011, the Tohoku Tsunami overtopped a weir and penetrated 49 km up the Kitakami River, the fourth largest river in Japan [1]. Similarly, the 2010 Chile tsunami propagated at least 15 km up the Maule River [2]. In the Pacific Northwest of the United States, large tsunamis have occurred along the Cascadia subduction zone, most recently the ‘orphan tsunami’ of 1700 (Atwater et al. [3]). The expected future occurrence of a Cascadia tsunami and its penetration into the Lower Columbia River became the subject of “the Workshop on Tsunami Hydrodynamics in a Large River” held in Corvallis, Oregon, 2011. We found that tsunami penetration into the Columbia River is quite different from a typical river. The tsunami enters the vast river estuary through the relatively narrow river mouth of the Columbia, which damps and diffuses its energy. The tsunami transforms into a long period, small amplitude wave that advances to Portland, 173 km from the ocean. Understanding this unique tsunami behavior is important for preparing a forthcoming Cascadia tsunami event.

Morphological effects of damming on lower Zambezi River

The Zambezi River is the fourth largest river in Africa (after the Congo, Nile, and Niger), and it is the largest African river flowing into the Indian Ocean. The lower Zambezi in Mozambique is influenced by the presence of two very large reservoirs (Kariba dam and Cahora Bassa dam) that have modified the natural seasonal flows, as well as the sediment balance and morphology of the river. In particular, downstream of the Cahora Bassa reservoir down to the delta, no negligible effects are reported to take place, such as local scour, bank collapse, and shoreline progressive erosion (Davies et al., 2000; Beilfuss and Dos Santos, 2001). In order to quantify and possibly mitigate these effects, a simplified numerical model of the sediment transport and erosion/sedimentation phenomena along the lower Zambezi has been developed, capable to deal with the scanty and uncertain data available. Indeed, besides the systematic flow records at the dam sites and few occasional measurements of turbidity and bottom granulometry, only the Digital Elevation Model (DEM) of the river will be used for the model. The objective of this paper is to predict the present and future effects of the presence of the Kariba and Cahora Bassa dams on the downstream morphology, integrating the few coarse and nonsimultaneous data, somehow improving their overall quality. The model reproduces the time and space propagation of the disturbances, that confirm, with more generality, the qualitative response of the river to the constructions of dams, anticipated by various geomorphologists. In fact, the reduction of waterflow seems to have an immediate effect downstream by initially fostering the sediment deposition. Subsequently, the total interception of sediment by the dam slowly takes over and inverts this tendency. A slightly smaller aggradation (or slightly larger degradation) rate with respect to the natural conditions (no dams) seems to represent the dominant effect of damming in the long term evolution of the lower Zambezi.

Downstream Migrations of Juvenile Salmon and Other Fishes in the Upper Yukon River

The Yukon River is the fourth largest river in North America, yet the ecology of its fishes has not been well described. During the spring and summer of 2002– 04, we sampled the downstream migrations of fishes in the Yukon River mainstem near the Canada-U.S. border, using a rotary auger trap. Age-0 juvenile chinook salmon, Oncorhynchus tshawytscha, were the most common fish in the catch, and they peaked in abundance in mid-June. Smaller numbers of age-1 chinook salmon and age-0 chum salmon, O. keta, were caught earlier in the season. Over 80% of the remaining catch consisted of young-of-theyear Coregoninae (whitefish), presumably moving from natal areas to summer rearing habitats. Few adult whitefish were captured, probably because our sampling terminated before fall spawning migrations began. Both juveniles and adults were captured for six other winter or spring spawning species that we encountered. Our results indicate that the Yukon River mainstem is used extensively as a migration corridor. This reach of the mainstem has very high suspended sediment levels in summer; its significance as rearing habitat remains unknown. Further studies are required to delineate the extent of migrations and the population structure for the non-anadromous species.

Contamination of River Kymijoki sediments with polychlorinated dibenzo- p-dioxins, dibenzofurans and mercury and their transport to the Gulf of Finland in the Baltic Sea

Kymijoki, the fourth largest river in Finland, has been heavily polluted by pulp mill effluents as well as the chemical industry. Up to 24 000 ton of wood preservative, chlorophenol known as Ky-5, was manufactured in the upper reaches of the river, an unknown amount of which was discharged into the river between 1940 and 1984. Polychlorinated dibenzo- p-dioxins and dibenzofurans (PCDD/Fs) occurred as impurities in the final Ky-5 product. The PCDD/F concentrations and burden in the river sediments were studied and the transport of PCDD/Fs from contaminated sites downstream and into the Gulf of Finland in the Baltic Sea was estimated. More than 190 sediment cores were sampled to estimate the volume of contaminated sediments and the total PCDD/F burden. The transport of PCDD/Fs was estimated using sediment traps placed at several sites. The survey revealed that sediments in the river were heavily polluted by PCDD/Fs, the main toxic congener being 1,2,3,4,6,7,8-heptachlorodibenzofuran, a major contaminant in the Ky-5 product. The mean total concentration at the most polluted river site downstream from the main source was 42 000 μg kg −1 d.w. (106 μg I-TEQ kg −1). The elevated concentrations in the coastal region and the present estimated transport from the River Kymijoki confirm earlier assessments that the river is a major source of PCDD/F for the Gulf of Finland.

A Simple Predictive Tool for Lower Brahmaputra River Basin Monsoon Flooding

AbstractThe Brahmaputra River of South Asia is the fourth largest river in the world in terms of annual discharge. The lower Brahmaputra River basin is susceptible to catastrophic flooding with major social, economic, and public health impacts. There is relatively little rainfall and snowpack information for the watershed, and the system is poorly understood hydrologically. Using a combination of available remotely sensed and gauge data, this study analyzes snow cover, rainfall, and monsoon period discharge for a 14-yr time period (1986–99). It is found that interannual rainfall variability is low and is a weak predictor of monsoon discharge volumes. Strong evidence is found, however, that maximum spring snow cover in the upper Brahmaputra basin is a good predictor of the monsoon flood volume. Despite the temporal and spatial limitations of the data, this study’s analysis demonstrates the potential for developing an empirical tool for predicting large flood events that may allow an annual early window for mitigating flood damages in the lower Brahmaputra basin, home to 300 million people.

Feeding Ecology of the Exotic Red Swamp Crayfish, Procambarus Clarkii (Girard, 1852) in the Guadiana River(Sw Iberian Peninsula)

[The feeding ecology of the red swamp crayfish, Procambarus clarkii was studied from October 1999 to September 2000 in the River Guadiana, the fourth largest river in the Iberian Peninsula. Analysis of the gut contents of 1225 individuals [15.8-172.3 mm total length (TL)] from 23 sites showed a diet dominated by plants [Relative Importance Index (RI) = 50.34] and animals (RI = 31.25), followed by amorphous material (RI = 12.21) and sand (RI = 6.20). Animal food items were represented by insects, mainly dipterans (RI = 34.59) and ephemeropterans (RI = 16.10), crayfish (RI = 15.14), and fish (RI = 11.40). Classes I (TL ≤ 40 mm) and II (TL = 40.1-80 mm) had a diet dominated by animals and amorphous material. Classes III (TL = 80.1-120 mm) and IV (TL > 120 mm) had a diet dominated by plants and amorphous material. Plants were consumed by all classes throughout the year, being most important for classes III and IV in autumn and winter. For classes I and II, animal diets are important throughout the year with increasing consumption in autumn and winter. Crayfish fragments were found throughout the year in all classes with more importance in spring and summer for classes III and IV. Similarly, fish were found in the guts of the crayfish throughout the year, this prey being more important in classes III and IV in the cold seasons. The diets of males and females were very similar, although females consumed more plants (RI = 48.72) than males (RI = 46.58). In contrast, males consumed more animal prey than females (RI = 32.36 and RI = 31.30, respectively). Differences in diet between males and females were not significant (G = 0.189, df: 3, P = 0.973)., The feeding ecology of the red swamp crayfish, Procambarus clarkii was studied from October 1999 to September 2000 in the River Guadiana, the fourth largest river in the Iberian Peninsula. Analysis of the gut contents of 1225 individuals [15.8-172.3 mm total length (TL)] from 23 sites showed a diet dominated by plants [Relative Importance Index (RI) = 50.34] and animals (RI = 31.25), followed by amorphous material (RI = 12.21) and sand (RI = 6.20). Animal food items were represented by insects, mainly dipterans (RI = 34.59) and ephemeropterans (RI = 16.10), crayfish (RI = 15.14), and fish (RI = 11.40). Classes I (TL ≤ 40 mm) and II (TL = 40.1-80 mm) had a diet dominated by animals and amorphous material. Classes III (TL = 80.1-120 mm) and IV (TL > 120 mm) had a diet dominated by plants and amorphous material. Plants were consumed by all classes throughout the year, being most important for classes III and IV in autumn and winter. For classes I and II, animal diets are important throughout the year with increasing consumption in autumn and winter. Crayfish fragments were found throughout the year in all classes with more importance in spring and summer for classes III and IV. Similarly, fish were found in the guts of the crayfish throughout the year, this prey being more important in classes III and IV in the cold seasons. The diets of males and females were very similar, although females consumed more plants (RI = 48.72) than males (RI = 46.58). In contrast, males consumed more animal prey than females (RI = 32.36 and RI = 31.30, respectively). Differences in diet between males and females were not significant (G = 0.189, df: 3, P = 0.973).]

Modeling the transport of PCDD/F compounds in a contaminated river and the possible influence of restoration dredging on calculated fluxes.

River Kymijoki, the fourth largest river in Finland, has been heavily polluted by pulp mill effluents as well as by chemical industry. Loading has been reduced considerably, although remains of past emissions still exist in river sediments. The sediments are highly contaminated with polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated diphenyl ethers (PCDEs), and mercury originating from production of the chlorophenolic wood preservative (Ky-5) and other sources. The objective of this study was to simulate the transport of these PCDD/F compounds with a one-dimensional flow and transport model and to assess the impact of restoration dredging. Using the estimated trend in PCDD/F loading, downstream concentrations were calculated until 2020. If contaminated sediments are removed by dredging, the temporary increase of PCDD/F concentrations in downstream water and surface sediments will be within acceptable limits. Long-term predictions indicated only a minor decrease in surface sediment concentrations but a major decrease if the most contaminated sediments close to the emission source were removed. A more detailed assessment of the effects is suggested.

A geochemical investigation of carboxylic acids released via sequential treatments of two surficial sediments from the Changjiang delta and East China Sea

Two surface sediments from the delta of the Changjiang River (the fourth largest river in the world in terms of water discharge and the seventh in terms of sediment discharge) and an adjacent area of the East China Sea were subjected to sequential treatments in order to obtain complete, quantitative and qualitative, information on carboxylic acid moieties. Five successive treatments allowed for the release of all acid moieties occurring in each sample: (i) the “unbound” acids isolated from extracts, (ii) the OH −-labile acids released by classical saponification, (iii) the OH −(PTC)-labile acids obtained via an additional saponification with a phase transfer catalyst, (iv) the H +-labile acids released by a subsequent acid hydrolysis and (v) the tightly bound acids only released by thermolysis. These five fractions correspond to distinct pools whose occurrence reflects differences in the mode of linkage of the acid moieties and/or in the protection provided by the structures to which they are linked. Such analysis of acid moieties provided information on (i) the relative contributions from microalgae, bacteria and higher plants in the “delta” and “seaward” stations, (ii) the degree of early diagenetic alteration for the acids derived from these different sources and (iii) the types of microalgal and bacterial species implicated. These features were also compared with the results of the only previous study where the sequential treatments were applied, on surficial sediments from a sharply different environment (the Lena River delta, Arctic).

Mud sedimentation on the continental shelf at an accretionary margin—Poverty Bay, New Zealand

Sediments on the continental shelf, atop the accretionary prism of the eastern North Island, are dominated by mud. This situation reflects a highly erodible provenance of soft Tertiary sediments, active tectonism, meteorological extremes, and, in historical times, changing land use. Off Poverty Bay, mud is supplied by the Waipaoa River, New Zealand's fourth largest river in terms of sediment supply. Under normal conditions, suspended sediment is dispersed as surface or hypopycnal plumes that have a net northeastward or southward dispersal along the shelf, mainly in response to the prevailing wind‐driven circulation. During extreme floods with return periods of 10 years or more, fluvial suspended sediment concentrations are probably high enough to form subsurface or hyperpycnal plumes that move and disperse under gravity and shelf currents. After the 100 year Cyclone Bola event of 1988, reef communities of the inner shelf were temporarily inundated by a fluid mud layer. Surficial sediments and 3.5 kHz seismic reflection profiles reveal that mud accumulates in a subsiding synclinal basin occupying the middle shelf. Offshelf dispersal is hindered by the growing Lachlan and Ariel Anticlines along the outer shelf. As a result, 20 km3 of mud has been deposited since c. 18 ka, of which 8 km3 accumulated since c. 8 ka. This late Holocene rate is nearly five times lower than the modern rate of mud supply, which equates with the marked increase in terrestrial erosion following European deforestation in the late nineteenth century.

Changjiang river plume and suspended sediment transport in Hangzhou Bay

Hangzhou Bay is situated immediately south of the mouth of Changjiang, the fourth largest river in the world in both water and sediment discharge. Synoptic and anchor-station observations of hydrography and suspended sediment during July 1981, December 1982, and December 1983 have been used to describe the water and sediment discharge from Changjiang into Hangzhou Bay. A secondary Changjiang river plume is found to play an important role in both the circulation and sediment transport inside the bay. The plume front serves as a guide for sediment transport and it may be related to the rapid accretion at the south shore of Hangzhou Bay.