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1.
The peculiarities of the hydrological regime of the delta and near-shore zone of the Po River are discussed. The intrusion of salt seawater into the delta is described. The history of the Po Delta formation has been restored on the basis of the analysis of historical, archeological, and cartographic data. As shown, the peculiarities of hydrological and morphological processes in the Po River mouth are associated with natural and specifically with human-induced variations in sediment runoff of the river, with levee construction along branches, subsidence of deltaic deposits, and eustatic rise of the sea level. 相似文献
2.
The main features of the structure and water regime of the mouth area of the Senegal River and their changes caused by river regulation in its upper reaches and within its delta area are considered. Data on water and sediment runoff of the Senegal River and their variations along the river are specified. River runoff was found to dramatically decrease in recent decades because of a drought. Zoning of river mouth area was carried out, and morphological processes in its estuary, in particular, the formation of a new outlet of the river into the ocean with the formation of a lagoon, are described. 相似文献
3.
M. V. Mikhailova 《Water Resources》2016,43(5):766-778
Data on several river deltas are used to analyze the regularities in their dynamics in the context of variations of water and sediment runoff, sea level, and hydroengineering activities in delta areas. The basis for this analysis includes the results of many-year studies of river deltas in Russia and the world. The specific features of the evolution of the structure and morphometry of bayhead deltas, forming in bays, lagoons, and estuaries are shown in the case of the Alikazgan delta in the Terek mouth area and the deltas of two watercourses in the Mississippi mouth area. Data on many-year variations of the morphometric characteristics of modern protruding deltas in open coastal zones are systematized, and the factors that have an effect on these changes are analyzed. The types of delta formation processes and the types of deltas are considered with regard to the factors involved. The majority of modern river deltas are found to slow down their progradation into seas under the effect of anthropogenic runoff decline; moreover, some deltas have started retreating and degrading. 相似文献
4.
M. V. Mikhailova 《Water Resources》2010,37(2):160-171
The peculiarities of the hydrological regime of the Orinoco River and the coastal zone of the Atlantic Ocean that affect the
hydrological-morphological processes in the mouth area of the Orinoco River are considered. The major features of the delta
water regime, including its inundation, runoff distribution over the delta branches, water and sediment balance, and the processes
of river and sea water mixing are described. Special attention is paid to the morphological processes at the Orinoco mouth
(delta evolution and modern processes at its coastline). 相似文献
5.
Main features of sediment regime in the mouth area of the Hong Ha River (Red River), Vietnam, are discussed. As shown, the hydraulic engineering construction on the Da tributary resulted in a nearly two-fold decrease of river sediment yield. Sediment budget components at the river mouth were analyzed to establish that more than 90% of the sediment yield was detained in the delta branches and in the nearshore zone of the river mouth. Morphological processes in the Hong Ha River mouth area were characterized in detail including delta evolution during Holocene and the dynamics of its channel network, coastline, and mouth bars. Special attention was given to modern processes of delta progradation at the mouths of main branches and to wave erosion of other parts of the delta coastline. The causes for the intensification of this kind of erosion and change of the delta type in the late XX century are discussed. 相似文献
6.
Transformation of the Ebro River Delta under the Impact of Intense Human-Induced Reduction of Sediment Runoff 总被引：1，自引：0，他引：1
The regularities of the Ebro River delta formation and the impact of hydraulic construction on the river sediment runoff are discussed. As shown, the drastic reduction of the sediment runoff after the construction of two large reservoirs in the lower river reaches in the 1960s slowed down the delta protrusion and intensified the delta coastline washout. 相似文献
7.
General information on the Nile River basin is presented. Specific features of the morphological regime of the Nile Delta and its near-shore zone, as well as the delta water balance and groundwater regime are discussed. The dynamics of the sea coastline of the Nile Delta is described in great detail. It is shown that the recent delta of the Nile and its sea coastline have been formed under the joint impact of the eustatic sea level rise, subsidence of sediments in the northern part of the deltaic plain, and considerable decrease in the river sediment runoff after the construction of the Aswan High Dam. 相似文献
8.
The main features of hydrological processes taking place in the mouth area of the Hong Ha River in Vietnam are considered.
The geographic and hydrological conditions in the Hong Ha River basin and in its receiving water body—the Gulf of Tonkin,
South China Sea—are briefly characterized. The main features of the mouth area of the Hong Ha River as a specific geographic
object are identified. The hydrological regime of the delta and the nearshore zone of the Hong Ha River are described in detail.
Water balance of the delta, runoff water levels and delta inundation, water and sediment runoff distributions over delta branches,
and the effect of tides, typhoons, and storm surges on delta regime are considered. Present-day problems of the use and protection
of natural resources at the Hong Ha River mouth are briefly discussed. 相似文献
9.
M. V. Mikhailova 《Water Resources》2009,36(1):26-42
Data on the Colville River mouth (Alaska, USA) are used to discuss the regularities in hydrological processes taking place in river mouth areas, functioning under extreme arctic conditions. Seasons and periods are recognized in the annual cycle of the Colville river mouth hydrologic regime. A thick ice cover commonly forms in winter in the river, its delta distributaries, and the offshore zone. Water salinity in under-ice water in the distributaries and near-delta river reach appreciably increases in late winter. The spring flood is very short; in this period, snowmelt water propagates toward the ocean first over ice and next under it. A wedge of freshened waters forms in the nearshore zone above fast ice. River runoff abruptly drops in the summer-autumn low-water period. The morphological processes in the distributaries and some ecological conditions in the delta are also discussed. 相似文献
10.
Tidal shear front off the Yellow River mouth has been observed and modeled in the previous studies. However, a detailed investigation of the front generation has not been conducted. The aim of this paper is to use a three-dimensional tidal model coupled to a sediment transport module to examine the front formation. The model predicted a tidal shear front that propagated offshore and lasted 1–2 h at both flood and ebb phase off the Yellow River mouth. The sensitivity numerical experiments showed that the topography with a strong slope off the Yellow River mouth was a determining factor for the front generation, and a parallel orientation between the major axes of ellipses and co-tidal lines of maximum tidal current was a necessary condition. While the bottom friction and the river runoff had no effect on the front location but affected the front intensity, the front generation was not sensitive to the coastline variation. The study concluded that the bottom slope off the river mouth induces a strong variation in the bottom stress in a cross-shore direction, which produces both maximum phase gradient and sediment concentration variability across the tidal shear front. With the extending Yellow River delta, the tidal shear front under the new bathymetry of year 2003 has been strengthened and pushed further offshore due to an increased bottom slope. 相似文献
11.
M. V. Mikhailova 《Water Resources》2006,33(5):523-534
Sediment balance at river mouths—a physical basis of delta dynamics—is considered. The specific features of relationships between sediment balance components at a mouth of a river are established for a stable, rising, or dropping sea level. The development of the delta of the Chilia branch at the Danube mouth is considered as an example of delta dynamics under the conditions of a relatively stable sea level. The evolution of the Sulak delta in the Caspian Sea with a highly variable level is considered as an example of delta dynamics in the case of a considerable rise and drop of water level in the water body. The anthropogenic reduction of sediment runoff of the rivers (by a factor of two in the Danube, and by a factor of nine in the Sulak) is taken into account. The relationship between the sediment runoff of a river and the volume of the “backwater prism” that formed due to sea level rise is shown to be the key factor in the development of delta in the case of sea level rise. In the case of a drop in the sea level, the relationship between the “active” and “passive” progradation of the delta into the sea is determined by the sediment runoff of the river, the rate of sea level drop, and the bed slope in the coastal area of the nearshore zone. 相似文献
12.
The evolution of the Ganges and Brahmaputra river delta during the Holocene period is discussed. Particular attention is given to the processes of delta formation, the dynamics of the delta hydrographic systems, the channel processes in river branches, as well as to the dynamics of the delta coastline and nearshore zone bed over the last 150–200 years. The calculation of sediment budget in the mouth area of these rivers is presented. 相似文献
13.
ＷＥＴＬＡＮＤＬＯＳＳＩＮＣＯＡＳＴＡＬＬＯＵＩＳＩＡＮＡＭｅｎｇｌｏｕＷＡＮＧ１ａｎｄＤｏｎａｌｄＤｅａｎＡＤＲＩＡＮ２ＡＢＳＴＲＡＣＴＷｅｔｌａｎｄｓｉｎｔｈｅＭｉｓｉｓｓｉｐｐｉＲｉｖｅｒｄｅｌｔａｉｃｐｌａｉｎａｒｅｖａｌｕａｂｌｅｒｅｓｏｕ... 相似文献
14.
Mikhailov V. N. Korotaev V. N. Mikhailova M. V. Congxian Li Shuguang Liu 《Water Resources》2001,28(4):351-363
The features of the hydrological regime, modern morphological structure, fluviomorphological processes, and the history of formation of the Yangtze River mouth area are discussed. The influence of the huge river water and sediment runoff and tides on the hydrological and morphological processes in the Yangtze River mouth is shown. The possible impact of construction of the large waterworks Three Gorges on the hydrological and morphological processes in the Yangtze River mouth is roughly evaluated. 相似文献
15.
Hydrological and Morphological Processes in the Kura River Delta 总被引：1，自引：0，他引：1
Peculiarities of the development of the Kura Delta over the last 200 years are discussed. As shown, changes in the delta were greatly affected by the Caspian Sea level drop during 1929–1977 and its rise during 1978–1995 as well as by natural and human-induced variations in the water and sediment runoff of the river. It was noted that the delta area decreased by nearly 40% as a result of the sea level rise. The following significant changes in the Kura Delta were revealed in recent years using space images: river water rushed through the right mouth spit and, hence, the main Southeastern Branch was devoid of its flow and a new sea spit began its formation in the branch mouth using wave-cut products. 相似文献
16.
Sediment discharge of the Yellow River (China) and its effect on the sedimentation of the Bohai and the Yellow Sea 总被引：6，自引：0，他引：6
The Yellow River is noted for its small water discharge and huge sediment load, which amounts to about11 × 108 tons every year, contributing 17% of the world's fluvial sediment discharge to the ocean. This has a profound effect on the sedimentation of the Bohai and the Yellow Sea. Changes of the outlet in the modern delta every 10 y result in frequent changes in the recession and progradation of the deltaic coastline both in space and time, and is the main reason why the Yellow River has not succeeded in building a bird-foot delta like the Mississippi. Owing to the huge sediment input from the Yellow River, the sedimentation rate of the Bohai is very high, about 0.6 m ka−1, but it is unlikely that the Bohai will be filled up in a few thousand years. In the late Quaternary period, the Yellow River extended its course across the Yellow Sea at least 4 times and probably discharged its heavy load into the Okinawa Trough during the last glacial maximum (15,000 B.P.). 相似文献
17.
V. N. Mikhailov D. V. Magritsky V. I. Kravtsova M. V. Mikhailova M. V. Isupova 《Water Resources》2012,39(1):11-43
Regularities in the response of the mouths of major rivers, flowing into the Caspian Sea, to large-scale variations in its
level and river water runoff and sediment yield are considered. Changes in the morphological structure and hydrological regime
of the Volga, Terek, Sulak, Ural, and Kura mouths have been analyzed in both geological past and separately for three modern
periods: a considerable drop in Caspian Sea level before 1978, its abrupt rise in 1978–1995, and a relative stabilization
in the subsequent years. Specific features were identified in the hydrological-morphological processes in different mouths,
caused by the differences in river sediment yields, and the slopes of delta surface and mouth nearshore beds. Some theoretical
and methodological approaches were verified in the analysis and evaluation of the processes under consideration. The obtained
results of studies of the mouths of rivers flowing into the Caspian Sea can be regarded as examples and analogues in the assessment
of processes, which take place at the mouths of other Russian and world rivers at present and can take place in the future
under anticipated natural and anthropogenic variations in sea level and river runoff. 相似文献
18.
Jan Pietroń Jeffrey A. Nittrouer Sergey R. Chalov Tian Y. Dong Nikolay Kasimov Galina Shinkareva Jerker Jarsjö 《水文研究》2018,32(2):278-292
The Selenga River delta (Russia) is a large (>600 km2) fluvially dominated fresh water system that transfers water and sediment from an undammed drainage basin into Lake Baikal, a United Nations Educational, Scientific, and Cultural Organization World Heritage Site. Through sedimentation processes, the delta and its wetlands provide important environmental services, such as storage of sediment‐bound pollutants (e.g., metals), thereby reducing their input to Lake Baikal. However, in the Selenga River delta and many other deltas of the world, there is a lack of knowledge regarding impacts of potential shifts in the flow regime (e.g., due to climate change and other anthropogenic impacts) on sedimentation processes, including sediment exchanges between deltaic channels and adjacent wetlands. This study uses field measurements of water velocities and sediment characteristics in the Selenga River delta, investigating conditions of moderate discharge, which have become more frequent over the past decades (at the expense of peak flows, Q > 1,350 m3 s?1). The aims are to determine if the river system under moderate flow conditions is capable of supporting sediment export from the main distributary channels of the delta to the adjacent wetlands. The results show that most of the deposited sediment outside of the deltaic channels is characterized by a large proportion of silt and clay material (i.e., <63 μm). For example, floodplain lakes function as sinks of very fine sediment (e.g., 97% of sediment by weight < 63 μm). Additionally, bed material sediment is found to be transported outside of the channel margins during conditions of moderate and high water discharge conditions (Q ≥ 1,000 m3 s?1). Submerged banks and marshlands located in the backwater zone of the delta accumulate sediment during such discharges, supporting wetland development. Thus, these regions likely sequester various metals bound to Selenga River sediment. 相似文献
19.
WANG Hou-jie YANG Zuo-sheng LI Rui-jie ZHANG Jun and CHANG Rui-fang Estuarine & Coastal Studies Ocean University of Qingdao Qingdao China Traffic Ocean Engineering College Hohai University Nanjing China corresponding 《国际泥沙研究》2001,16(4)
1 wrsoorCnoxThe Yenow mver delta is ereated by the river transponing sediment bom the Loess Plateau to the shallOWBOhai Gulf during the paSt l45 years. lh recent years, the water discharge and sediment load enedg thesea have bein ched dramacaily The river end chann shital northeastWed hom QingshulgOuN to qngshulgou-Chah chaDnel in 1996, resulting in a new regfor of sedimenboon and erosion ofthe subaqucous delta.,A nUInerial model for river sediInen dispersion and seabed mOrPhofogy of t… 相似文献
20.
Tomasz Kolerski 《Acta Geophysica》2014,62(4):893-914
The mouth of the Vistula River, which is a river outlet located in tideless area, is analyzed. The Vistula River mouth is a man-made, artificial channel which was built in the 19th century in order to prevent the formation of ice jams in the natural river delta. Since the artificial river outlet was constructed, no severe ice-related flood risk situations have ever occurred. However, periodic ice-related phenomena still have an impact on the river operation. In the paper, ice processes in the natural river delta are presented first to refer to the historical jams observed in the Vistula delta. Next, the calibrated mathematical model was applied to perform a series of simulations in the Vistula River mouth for winter storm condition to determine the effects of ice on the water level in the Vistula River and ice jam potential of the river outlet. 相似文献