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1.
Estuarine projects can change local topography and influence water transport and saltwater intrusion. The Changjiang (Yangtze) River estuary is a multichannel estuary, and four major reclamation projects have been implemented in the Changjiang River estuary in recent years: the Xincun Shoal reclamation project (RP-XCS), the Qingcao Shoal reclamation project (RP-QCS), the Eastern Hengsha Shoal reclamation project (RP-EHS), and the Nanhui Shoal reclamation project (RP-NHS). The effects of the four reclamation projects and each project on the saltwater intrusion and water resources in the Changjiang River estuary were simulated in a 3D numerical model. Results show that for a multichannel estuary, local reclamation projects change the local topography and water diversion ratio (WDR) between channels and influence water and salt transport and freshwater utilization in the estuary. During spring tide, under the cumulative effect of the four reclamation projects, the salinity decreases by approximately 0.5 in the upper reaches of the North Branch and increases by 0.5–1.0 in the middle and lower reaches of the North Branch. In the North Channel, the salinity decreases by approximately 0.5. In the North Passage, the salinity increases by 0.5–1.0. In the South Passage, the salinity increases by approximately 0.5 in the upper reaches and decreases by 0.2–0.5 on the north side of the middle and lower reaches. During neap tide, the cumulative effects of the four reclamation projects and the individual projects are similar to those during spring tide, but there are some differences. The effects of an individual reclamation project on WDR and saltwater intrusion during spring and neap tides are simulated and analyzed in detail. The cumulative effect of the four reclamation projects favors freshwater usage in the Changjiang River estuary.
相似文献2.
《中国海洋湖沼学报》2018,(6)
Based on the MIKE 21 numerical model combined with measured data, a numerical model for the coupling of water and salinity in the Changjiang(Yangtze) River estuary was established, and based on good verification, the influence of the tidal current intensity on the transport and variations of salinity concentrations in saline water from the North Branch to the South Branch was numerically evaluated. The time and space mean root mean square of the tidal current velocity can be expressed as a parabolic function of an adjustment coefficient for the amplitude of the M2 tidal constituent along the open boundaries of the model. Under the advection of runof f and tidal currents, the saline pool is transported downstream in an oscillatory pattern. With the enhancement of tidal current intensity, the oscillatory motion of the saltwater pool is increasingly significant in a tidal cycle forced by rising and falling tides. Along four set paths, the daily average concentrations of the saline core were generally similar, and in the process of transportation downstream, the concentrations of saltwater declined. The decay of the tidal-period-averaged salinity of the saltwater was linearly related to the square of the tidal current. Thus, the tidal current has a significant and direct impact on saltwater transport and diffusion in the Changjiang River estuary. 相似文献
3.
MIXING OF SALT WATER AND FRESH WATER IN THE CHANGJIANG RIVER ESTUARY AND ITS EFFECTS ON SUSPENDED SEDIMENT 总被引：3，自引：0，他引：3
Using field hydrological data, the relationship between the mixing of salt water and fresh water and the tidal range/ high tidal level in the Changjiang (Yangtze) River estuary is discussed, and the transporting and concentrating of suspended sediment in the estuary were also analysed in respect to the circulation, flocculation and stratified interface resulting from mixing.The calculation results by two-dimentional box model have confirmed the effects of the circulation on the concentrating of suspended sediment in the estuary. The conclusions derived from this work have deepened the understanding on the mixing in the Changjiang River estuary and are of significance in bo'th theory and practice. 相似文献
4.
As a multi-branch estuary system, the Yangtze Estuary presents distinctive characteristics of hydrodynamic processes through co-action among river runoff, tides, wind-waves, and gravitational circulation. To study the pathways of flushing water along all of the estuary's branches and analyze their differences, especially those due to the influence of seawater intrusion and discharge variations, a free surface flow modeling suite TELEMAC-MASCARET involving passive tracers was applied to the Yangtze Estuary and the adjacent waters. The open boundary conditions were provided by the Nao.99 b model(Matsumoto et al., 2000), which was calibrated using observed velocity and salinity data obtained in March 2002. The water age, which was used as the diagnostic tool to study the flushing efficiency of the water body across the estuary, was solved by additional advection-diffusion-reaction equations implemented in the TELEMAC modeling system. The transport properties were investigated under different river discharge scenarios, which represented seasonal impacts; aspects relating to the influence of tide, surface wind stress, and density-induced circulation on age were also investigated. Model results showed that river runoff is one of the dominant factors influencing the spatial distribution of the mean age, while tidal force is another important factor. The horizontal freshwater age distribution demonstrated similarity compared with the salinity distribution; the vertical age distribution resembled the stratification pattern of salinity in all branches where stratification persists. An experimental numerical simulation of tracing saltwater age from the lower reaches of the estuary was conducted, and implicated the connectivity with transport processes of freshwater from upstream. Additionally, a particle tracking algorithm was used to analyze the dynamic characteristics of the four passages. The South Passage and South Channel were found to be significant as main water flow passages, while salinity intrusion in the North Branch was found to cause a return flow that partially joins the South Branch flushing water. 相似文献
5.
SEDIMENT TRANSPORT IN YALU RIVER ESTUARY 总被引：4，自引：0，他引：4
GAOJian-hua GAOShu CHENGYan DONGLi-xian ZHANGJing 《中国地理科学(英文版)》2003,13(2):157-163
Tidal cycle measurements of tidal currents, salinity and water temperature, and suspended sediment concentra-tions were measured at four stations, together with surveys along two profdes short core collection within the Yalu River estuary.Grain size analysis of the three core sed~ment showed that: 1 ) the sediment from B1 to B3 became finer, worse sorting andpositively skewed; 2) the diversification of matter origin became more and more evident from east to west; 3) the sedimenta overthe region were of the same origin, as indicated by their similar colors and grain sizes. The data indicated that stratification occurred in the flood season, from upstream to downstream, and a salt wedge was formed. The water column was well mixed, butthe longitudinal gradient of the salinity was larger on spring tide. The resulta also showed that the dominating mechanism ofsuspended sediment transport in the Yalu River estuary was T1, T2, T3 and T5. The non-tidal steady advection transport wasrestricted by the net transport of suspended sediment induced by mass Stoked drift directed to landwards, then the net sedimenttransport rate were decreased and the turbidity maxima was also favored to forming and extending. 相似文献
6.
Distribution of suspended matter in seawater in the Southern Yellow Sea is investigated in five regions: 1) the Northern Jiangsu
bank, the highest TSM (total suspended matter) content region; 2) the high TSM content region off the Changjiang River mouth;
3) the high TSM content region off the Chengshan Cape; 4) the low TSM region off Haizhou Bay; 5) the central part of the Southern
Yellow Sea, a low TSM content region. The vertical distribution of TSM is mainly characterized by a spring layer of suspended
matter, written as “suspended-cline” whose genesis is related to storms in winter. In this paper, non-combustible components
and grain sizes in suspended matter, relationship between suspended matter and bottom sediments, and salinity in seawater
are described. Investigation result shows that, in this area, suspended matter comes mainly from resuspended bottom sediment
and secondarily from present discharge loads from rivers and biogenic materials. Discharged sediments from the Huanghe River
move around the Chengshan Cape and affect the northwestern region of this area. Sediments from the Changjiang River affect
only the southern part and have little or no direct influence on the central deep region. Wave is the main factor affecting
distribution of suspended matter. Water depth controls the critical depth acted on by waves. The cold water mass in the central
region limits horizontal and vertical dispersions of terrigenous materials. Suspended matter here has the transitional properties
of the epicontinental sea. Its concentration and composition are different from those of a semi-closed sea (such as the Bohai
Sea) and those of the East China Sea outer continental shelf or those near oceanic areas. 相似文献
7.
A three-dimensional transportation model for suspended solids （SS） in Zhujiang （Pearl） River estuary, South China, was developed by coupling with a three-dimensional hydrodynamic model. The model was validated using hourly measured data of sediment contents during 25-26, July 1999. The results showed that modeled contents matched well with measured ones and that the modeled top layer distribution agreed with the remotely sensed image of suspended solids in summer. The modeled results showed clearly the layers of suspended solids in depth, with larger sediment contents in lower layers though in the interface between salt water and freshwater the lowest contents appeared in middle layer. In overall, the suspended solids inflow from 8 rivers,transport southwestward, and carried by strong coastal flow in Zhujiang River estuary. Contours of sediment contents in the estuary spread further to the open sea during ebb tide rather than flood tide which reflects that the suspended solids in the estuary are land sourced. 相似文献
8.
IMPACTS OF FUTURE SEA LEVEL RISE ON SALT WATER INTRUSION IN THE CHANGJIANG RIVER ESTUARY 总被引：1，自引：0，他引：1
杨桂山 《中国地理科学(英文版)》1992,2(1):30-41
Sea level rise could increase the salinity of an estuary by altering the balance between fresh water and salt water. The implications of sea level rise for increasing salinity have been examined in the Changjiang (Yangtze) River estuary. By correlative analysis of chlorinity, discharge and tidal level and calculation of two-dimensional chlorinity, distribution of the Changjiang River estuary, the changes of the intensity and lasting hours of salt water intrusion at Wusong Station and the changes of chlorinity distribution in the South Branch of the Changjiang River estuary have been estimated when future sea level rises 50-100 cm. The intensity of salt water intrusion in the future will be far more serious than current trend. 相似文献
9.
Results are presented of the longitudinal and vertical profiling of salinity and suspended particulate matter (SPM) at the Muthupet estuary, India, during a one year period under widely varying freshwater flow conditions. Freshwater flow was available during post-monsoon and monsoon. An up-estuary shift in the location of estuarine turbidity maxima (ETM) was observed during the transition from post-monsoon to pre-monsoon and further it shifted downstream during the transition from pre-monsoon to monsoon, thereby exhibiting a pronounced seasonal cycle. The salinity intrusion was dependent on the freshwater discharge and was expressed as a power function of freshwater flow, explaining 97% of the variance. The formation of a salt plug in Muthupet estuary and its seasonal dynamics were observed, which is not an identified feature of any of the Indian estuaries studied so far. The geographical positions of salt plug and ETM core were more or less the same during their formation. The occurrence of two ETM during the LW of post-monsoon and the absence of ETM during monsoon explains the strong seasonal variation in the formation of ETM. The primary factor affecting the formation of ETM was identified as the freshwater flow over an annual cycle; the resuspension of sediments by tidal current affecting the formation on a flood/ebb cycle was secondary. The extent of shift of ETM was found to be an inverse logarithmic function of the freshwater discharge. The separation between ETM intrusion and salinity intrusion increased two fold with the increase in ETM intrusion. 相似文献
10.
The circulations off the Changjiang mouth in May and November were simulatedby a three dimension numerical model with monthly averaged parameters of dynamic factors in this paper. The area covers the East China Sea (ECS), Yellow Sea and Bohai Sea. Simulated results show that the circulation off the Changjiang mouth in spring and autumn is mainly the Changjiang runoff and Taiwan Warm Current (TWC). The Changjlang discharge is much larger in May than in November, and the wind is westward in May, and southward in November offthe Changjiang mouth. The runoff in May branches in three parts, one eastward flows, the other two flow northward and southward along the Subei and Zhejiang coast respectively. The Changjiang diluted water expands eastward off the mouth, and forms a strong salinity front near the mouth. Surface circulation in autumn is similar to that in winter, the runoff southward flows along the coast, and the northward flowing TWC becomes weaker compared to that in spring and summer. The bottom circulations in May and November are mainly the runoff near the mouth and the TWC off the mouth, and the runoff and TWC are greater in May than in November. 相似文献
11.
Impact of seasonal tide variation on saltwater intrusion in the Changjiang River estuary 总被引：1，自引：0，他引：1
An improved 3-D ECOM-si model was used to study the impact of seasonal tide variation on saltwater intrusion into the Changjiang River estuary, especially at the bifurcation of the North Branch (NB) and the South Branch (SB). The study assumes that the river discharge and wind are constant. The model successfully reproduced the saltwater intrusion. During spring tide, there is water and salt spillover (WSO and SSO) from the NB into the SB, and tidally averaged (net) water and salt fluxes are 985 m3/s and 24.8 ton/s, respectively. During neap tide, the WSO disappears and its net water flux is 122 m3/s. Meanwhile, the SSO continues, with net salt flux of 1.01 ton/s, much smaller than during spring tide. Because the tidal range during spring tide is smaller in June than in March, overall saltwater intrusion is weaker in June than in March during that tidal period. However, the WSO and SSO still exist in June. Net water and salt fluxes in that month are 622 m3/s and 15.35 ton/s, respectively, decreasing by 363 m3/s and 9.45 ton/s over those in March. Because tidal range during neap tide is greater in June than in March, saltwater intrusion in June is stronger than in March during that tidal period. The WSO and SSO appear in June, with net water and salt fluxes of 280 m3/s and 8.55 ton/s, respectively, increasing by 402 m3/s and 7.54 ton/s over those in March. Saltwater intrusion in the estuary is controlled by the river discharge, semi-diurnal flood-ebb tide, semi-monthly spring or neap tide, and seasonal tide variation. 相似文献
12.
李身铎 《中国海洋湖沼学报》1987,5(1):22-33
This research on the vertical structure of tidal current in shallow water near the Changjiang River estuary is based on a great deal of observation data of current obtained recently, and a simple mathematic model. The essential features of the structure are: (1) the maximum velocity decreases with depth, the shallower the water, the lower the velocity; (2) the orientation of maximum velocity continuously deviates from the surface to the bottom to the left at the western side of the mouth bar and to the right at the eastern side; (3) the time of maximum velocity leads steadily with depth; (4) in general, tidal currents rotate clockwise, the nearer the sea-bed, the narrower the ellipse of the tidal current; (5) the ratio W1/W2 varies non-linearly with depth, and is smaller in the middle layer than at the surface and bottom. Bottom friction is the main cause of the vertical structure. 相似文献
13.
lmooUcrI0NSuspendedrnatter(SM)wasanimPortantsubjeCtofstudyincomPrehensiveoasnographicsurveyinChinaintheendofthel950s.Inthel97ds,somesdentistSpeonjo,l974,Yatomoto,l979,EInery,l978)studndextenSiveynoncombustiblematterandgrainsizedistributionsinSManditSreintionshiptoupwelling.Inthel980s,TotaIsuspendedmatternyM)distributionintheEastChinaSea(Ees)wasinvestisatalduringtheChinaisjointstudyonsedhedynaAnesthere.YangZuosheng(l992)distaltherelationbeweenthemacrostrUctureofSMtIansportanddistrib… 相似文献
14.
Spatial distributions and seasonal variations of picoplankton (i.e. Synechococcus spp., Prochlorococcus spp., picoeukaryotes and heterotrophic bacteria) and viruses in the Changjiang estuary have been reported in the past. However,
short-term variations (e.g. at a tidal timescale) of these organisms and their regulating factors remain unclear. We determined
the time-series of fluctuations of picoplankton and viruses with tide simultaneously in flow cytometry in the Changjiang estuary
during a cruise in June 2006, in which a tidal model based rectangle equation was applied. The results indicate that high
cell abundances of picoplankton and viruses occurred during flood tide and low cell abundances during ebb tide. The period
of the surface cell abundance variations was about 13 h, suggesting the surface cell abundances in the Changjiang estuary
were largely regulated by tide. However, cell abundances in middle and bottom waters varied in different periods due to influences
of tidal induced physical forces such as resuspension and stratification. Therefore, tidal action is an important factor for
the diel variations of picoplankton and viruses in the Changjiang estuary. 相似文献
15.
A modelling study of inter-annual variation of Kuroshio intrusion on the shelf of East China Sea 总被引：2，自引：1，他引：1
Inter-annual variability of the Kuroshio water intrusion on the shelf of East China Sea (ECS) was simulated with a nested global and Northwest Pacific ocean circulation model. The model analysis reveals the influence of the variability of Kuroshio transport east of Taiwan on the intrusion to the northeast of Taiwan: high correlation (r = 0.92) with the on-shore volume flux in the lower layer (50–200 m); low correlation (r = 0.50) with the on-shore flux in the upper layer (0–50 m). Spatial distribution of correlations between volume fluxes and sea surface height suggests that inter-annual variability of the Kuroshio flux east of Taiwan and its subsurface water intruding to the shelf lag behind the sea surface height anomalies in the central Pacific at 162°E by about 14 months, and could be related to wind-forced variation in the interior North Pacific that propagates westward as Rossby waves. The intrusion of Kuroshio surface water is also influenced by local winds. The intruding Kuroshio subsurface water causes variations of temperature and salinity of bottom waters on the southern ECS shelf. The influence of the intruding Kuroshio subsurface water extends widely from the shelf slope northeast of Taiwan northward to the central ECS near the 60 m isobath, and northeastward to the region near the 90 m isobath. 相似文献
16.
��־�� 《中国海洋湖沼学报》2012,30(5):791-795
Based on the principle of conservative matter removal in estuary,a new method is proposed for estimating the ratio of sediment resuspension in estuaries with fine suspended sediments in the turbidity maximum zone(TMZ) of the Changjiang(Yangtze) estuary during 2005.Results show that there was a range of 18.7%±27.9% to 73.9%±22.5% per annum of total suspended particulate matter(SPM),with an average of 49.2%.Nearly half of the particulate matter in the TMZ originates from sediment resuspension.This indicates that sediment resuspension is one of the major mechanisms involved in formation of the TMZ.Compared with traditional method for calculating these ratios in the estuary,this new method evaluates the dynamic variation of SPM content carried by river runoff from the river mouth to the ocean.The new method produced more reliable results than the traditional one and could produce a better estimation of resuspension flux for particulate matter in estuaries. 相似文献
18.
The waters with salinity from 10 to 23 comprise the main removal region of ion and particulateforms of heavy metals in the Changjiang estuary.The positive correlationships between Zn,Cd,Pb,Cuand the reciprocal of transparency,COD and chlorophyll-a showed that the removal of heavy metalsclosely correlate with the distribution of suspensions,the adsorption of organic materials and theassimilation by organisms.The removal of heavy metals in the Changjiang estuary water were consistentwith the sedimentation rate of the sediments in these waters,sediment types and the distributions ofheavy metals contents in the sediments. 相似文献
19.
黄河三角洲是陆海交界地带,陆地海洋相互作用显著,泥沙所引起的岸滩演变、港口航道的淤积、水动力环境的改变等问题比较复杂。该文采用三维HEM-3D数值模型对黄河三角洲海域流场变化、盐度、悬浮泥沙浓度及海岸冲淤分布进行了潮流周期内的数值模拟分析。结果表明,黄河三角洲海域的悬浮泥沙浓度分布与潮流场变化和河口泥沙输入有密切的关系,在三角洲北部受五号桩外强潮流区的影响,近岸海底的泥沙发生明显的再悬浮,并在涨潮流向南输送,含沙量达1.5 g/L左右。在三角洲南部(现行河口区域和莱州湾区域),受现行河口入海泥沙扩散的影响显著。海域年冲淤分布,在北部废弃三角洲区域,由于海洋动力作用强烈,浅水冲刷,海底侵蚀显著,形成了明显呈沿岸展布的侵蚀中心,在侵蚀中心以外,侵蚀快速减弱。在现行河口区域,以淤积为主,在羽状流扩散的控制下,泥沙入海后向南输运,至莱州湾区域逐渐减弱。数值模拟的结果与卫星遥感解译的岸线变化基本一致,效果良好。 相似文献
20.