Estimation of freshwater and material fluxes from the Yangtze River into the East China Sea by using TOPEX/Poseidon altimeter data     

Jiqun Zhang  Kaiqin Xu  Lianhui Qi  Yonghui Yang  Masataka Watanabe 《水文研究》2005,19(18):3683-3698

In order to determine material fluxes in rivers by non‐contact methods, it is essential to estimate river discharge first. Although developed and optimized for open oceans, satellite radar altimetry has the potential to monitor variations in the levels of inland waters such as lakes and rivers. Making use of the concept of an ‘assumed reference point’, we converted TOPEX/Poseidon satellite altimetry data on water level variations in the Yangtze River (Changjiang) to ‘water level’ data. We also used ‘water level’ time‐series data and in situ river discharge to establish a rating curve. By use of the rating curve, we converted data on ‘water level’ derived from 7 years (1993–99) of TOPEX/Poseidon data to actual river discharge. On the basis of statistical correlation between discharge and nutrient concentration data collected in 1987–88 and in 1998–99, we estimated the total amounts of freshwater and material fluxes transferred by the Yangtze River during the 1990s. The result reveals that an overall, but very slight, increase in freshwater and material fluxes occurred during the 1990s. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

A contrast analysis on the load character of the Changjiang River and the Huanghe River     

Wang Lachun  Zhang Jianxin  Chen Xiaoling  Chu Tongqing 《中国地理科学(英文版)》1997,8(4):317-325

According to the analysis of grain size, mineral composition and inclusion in quartz grain of the suspended and bed load sampled from the Changjiang (Yangtze) River and the Huanghe (Yellow) River, the authors reveal the differentiation of loads between the two rivers. In the Huanghe River the size of suspended load is coarser than that in the Changjiang River, while the bed load is on the contrary. Through heavy mineral analysis, the biotite content of the Huanghe River loads is much higher than that of the Changjiang River, and the monomorillonite content of the former is about two times higher than the latter. All those may be attributed to the effects of different material sources and hydraulic conditions on load. The analysis of inclusion in quartz grain definitely illustrates the environmental difference of material sources between the two rivers. In the meantime, it provides a new method in seeking source of river load. Subsidized by the National Natural Science Foundation. This paper is attributed to careful guidance from Prof. Wang Ying & Prof. Shi Yunliang.  相似文献   

Effects of sediment-induced stratification on floe breakup in an idealized tidal estuary: A numerical modelling study     

X. H. Wang 《中国海洋大学学报(英文版)》2004,3(2):115-122

Floe breakup dynamics are studied by a sediment transport numerical model in an idealized tidal estuary that has a constant water depth and rapid flocculation of cohesive sediments. The focus is placed on the effects of boundary layer stratification induced by a bottom nepheloid layer on floe breakup and size distribution in the water column. In a neutrally stratified estuary, the floe size distribution follows a parabolic function with maximum values at the surface and bottom. The sediment-induced stratification in the bottom boundary layer increases the median floe sizes. Furthermore, sediment-voided convection caused by the settling lutocline generates significant turbulent kinetic energy dissipation and reduces floe size at the depth where the convective mixing happens. Below that depth, a weak local maxima in the floe size is predicted due to presence of the lutocline. The effect of sediment-stratified bottom boundary layer on the floe breakup can be consistently approximated by a linear regression between the maximal floe size and flux Richardson number.  相似文献   

Simulated circulations off the Changjiang （Yangtze） River mouthin spring and autumn   总被引：1，自引：0，他引：1  

朱建荣戚定满  肖成猷 《中国海洋湖沼学报》2004,22(3):286-291

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   

Textural research on the main source of the Changjiang River     

Guangyou Sun  Wei Deng  Qingchun Shao  Runkui Hua 《中国地理科学(英文版)》1992,2(3):284-292

The Chinese people began to research the main source of the Changjiang (Yangtze) River 2,400 years ago. Limited by the scientific level, they did not discover it. The Tuotuo River was determined as the main source of the Changjiang River in the 1970s. However, this was not correct, because when comparing the length of the Tuotuo River with the Dam River, the glacier length at the headwaters was added to the Tuotuo River, resulting in that the Tuotuo River is 1 km longer than the Dam River, keeping in mind that the glacier can not be regarded as part of the river. In the summer of 1986, we investigated the source of the Changjiang River, we accurately measured the length of both the Tuotuo and Dam rivers, we discovered that the Dam River was 353.1 km long, and the Tuotuo River was 346.3 km long, the Dam River thus being 6.8 km longer than the Tuotuo River. The discharge of the Dam River is 196.18 m³/sec., 2.6 times as large as that of the Tuotuo River, that of the Tuotuo River is 75.10 m³/ sec. The drainage area of the Dam River is 1.8 times as larger as that of the Tuotuo River; the drainage area of the Dam River is 30,715.7 km², the Tuotuo River is 16,691.0 km². Through synthetic analysis of the factors mentioned above, we came to the conclusion that the main source of the Changjiang River is the Dam River instead of the Tuotuo River.  相似文献   

An analysis of the trophic network of a macrotidal estuary: the Seine Estuary (Eastern Channel, Normandy, France)     

Herv Rybarczyk  Bernard Elkaïm 《Estuarine, Coastal and Shelf Science》2003,58(4):775

A steady state, mass balance, trophic network has been constructed to illustrate the flow of energy in the Seine Estuary by using Network Analysis and Ecopath methods. This ecosystem shows 15 compartments from primary producers to the top consumers (fish and birds). This study has been compared with other ecosystems of comparable nature located in North America (Narragansett, Chesapeake, Delaware Bays), Europe (Ems Estuary, Dublin Bay and Bay of Somme), and South Africa (Swartkops Estuary) in which analysis of trophic network has been applied with similar methods.The Seine Estuary shows values of some global parameters and indices either close to large North American bays and a South African estuary characterised by the complexity of their trophic network, or values near European bays and estuaries, or else remain typical of the Seine estuary. All of this reflects specific functioning of the Seine Estuary which can be explained by the analysis of the dominant food web. In the upstream sector an important pelagic food web was found correlated with highest primary production, especially planktonic, which is rapidly consumed by an abundant zooplankton and suprabenthos (Mysidacae and Decapoda Crustacea). This reveals the dominant consumer role of this sector. The external fluvial inputs (277.80 gC m⁻² y⁻¹) are transferred to the downstream sector which produces the major export (548.43 gC m⁻² y⁻¹), in parallel with the low consumption and efficiency of dominant benthos component from its bentho-pelagic food web. This reflects the dominant exporter role of this sector.In the Seine Estuary low values of detritivory index D/H (2.52), recycling index FCI (16.1%) and connectance (0.24) were found associated with high values of P/B ratio (38.2%), sum of exports (548.43 gC m⁻² y⁻¹) and the great difference between ratio of ascendency to capacity development A/C and internal ratio A_i/C_i. This shows the lack of a dominant resource as in Delaware Bay, that the state of development is different from a mature ecosystem, and the dependance on external connections similar to the Bay of Somme, another ecosystem of Eastern Channel, France.  相似文献   

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  

沈焕庭  张重乐 《中国地理科学(英文版)》1992,2(4):373-381

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   

辽宁营口大辽河口水鸟多样性及季节动态     

曾娅杰  贾亦飞 《湿地科学与管理》2022,18(1):18-22

营口市大辽河口湿地是东亚-澳大利西亚迁飞区水鸟的重要栖息地。2019年,采用样线法和定点观察法,对大辽河口湿地水鸟进行监测,运用指数分析方法研究湿地水鸟多样性。结果表明:共记录到湿地水鸟5目10科45种230355只,其中,鸻形目29种,国家Ⅰ级保护动物2种,国家Ⅱ级保护动物5种,IUCN濒危物种2种,易危物种2种,近危物种2种,个体数量超过全球数量1%标准的有13种。从居留型来看,以旅鸟为主,其个体数量占水鸟个体总数的90.06%。大辽河口湿地水鸟多样性季节差异明显,春季的水鸟个体数量最高,8月的水鸟多样性指数最高,3月的水鸟均匀度指数最高。营口大辽河口湿地水鸟多样性高,种群数量大,已达到国际重要湿地的标准,应尽快纳入国家湿地保护体系。  相似文献   

长江中下游梅雨期降水与环流关系分析及模拟   总被引：5，自引：4，他引：5  

陈艺敏  钱永甫 《热带气象学报》2006,22(1):26-33

用点相关和SVD方法分析发现,长江中下游地区梅雨期降水的异常与前期(5月)和同期(6～7月)80～140°E,0～50°N区域附近的环流场的异常有关。当梅雨出现正(负)异常时,SVD分解的风场出现有利于(不利于)降水的主要分布模态。在用p-σ九层区域气候模式模拟初边条件的异常对梅雨降水的影响时,证实环流场异常对梅雨降水的影响比较显著。RegCM3模拟结果表明,1998年和1988年初边条件的异常对降水有明显的影响,长江流域的降水对此异常最为敏感。  相似文献   

江南汛期降水基本气候特征及其与海温异常关系初探   总被引：26，自引：10，他引：26       下载免费PDF全文

陈绍东  王谦谦  钱永甫 《热带气象学报》2003,19(3):260-268

分析了江南汛期降水异常的基本气候特征。指出:雨季开始于3月,雨量集中于春末夏初(4～6月),是中国东部雨季开始和结束均最早的地区。江南汛期降水近50年来略有减少的趋势。影响江南汛期降水的海温异常关键区位于9～1°S,121～129°E,关键影响时段为前一年的5～7月。长时间的海气相互作用使前期的海温异常影响了后期的大气环流,导致江南地区次年汛期的降水异常。  相似文献