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1.
Water level variations in the Kiliya Branch of the Danube Delta over the period of 40 years (1958–1997) were analyzed. These level variations were subdivided into three components related to long-term variations of the share of the branch runoff and its redistribution within a year resulting from the Danube flow regulation; subsidence of deltaic deposits; and backup caused by the rising Black Sea level. It was revealed that, during the low-flow period, this backup had propagated to the river mouth at a distance of 160 km. 相似文献
2.
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
3.
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
4.
Specific processes of delta formation at the Mississippi River mouth are discussed. In the last 7000–8000 years, a series
of large deltaic lobes was formed in succession at the Mississippi River mouth under the condition of high river sediment
runoff and stabilization of the ocean level after its sudden postglacial rise. In the mid-XX century, the formation of a new
deltaic lobe began at the Atchafalaya Branch mouth. Over the last centuries, the processes of delta formation at the Mississippi
River mouth slowed down as a result of the river sediment runoff decrease after flow regulation of the Missouri and Arkansas
tributaries; in some parts of the deltaic plain, these processes gave way to degradation of marshes and seashore erosion under
the impact of intense land subsidence. The current processes of delta formation are under the great influence of local economic
activities. 相似文献
5.
V. N. Mikhailov 《Water Resources》2010,37(2):145-159
The regime and budget of water and sediment runoff in the mouth area of the Amazon River are discussed. New values of the
water and sediment runoff at the terminal cross section (the town of Obidos) and at its outflow into the Atlantic Ocean have
been obtained on the basis of observational data. It turned out that the water runoff value was markedly higher and the sediment
runoff value was lower than it had been considered previously. 相似文献
6.
Long-term natural and human-induced variations in water and sediment runoff in the Danube Delta head were studied on the basis of analysis of an extremely long series of observations (1840–2002). A considerable reduction of sediment runoff in the second half of the 20th century related to sediment accumulation in reservoirs was revealed. It was found that human activities had an insignificant impact on the water runoff variations and the period of 1961–2002 turned out to be abnormally water-abundant. 相似文献
7.
ＴＯＷＡＲＤＳＡＮＥＷＡＰＰＲＯＡＣＨＴＯＣＯＮＳＴＲＵＣＴＩＮＧＳＥＤＩＭＥＮＴＤＩＳＣＨＡＲＧＥＲＡＴＩＮＧＣＵＲＶＥＳＷｏｌｆｇａｎｇＳＵＭＭＥＲ；ＺＨＡＮＧＷｅｉＡｂｓｔｒａｃｔ：ＴｈｅＳｅｄｉｍｅｎｔＲａｔｉｎｇＣｕｒｖｅ（ＳＲＣ）ｉｓｔｈ... 相似文献
8.
Abrupt changes of runoff and sediment load in the lower reaches of the Yellow River,China 总被引：2，自引：0，他引：2
Determining abrupt changes in runoff and sediment load may not only enhance identification of the principal driving factors for such changes but also help establish effective countermeasures for serious water deficit by managers in the Yellow River basin. We used the Mann-Kendall trend test and linear regression to determine trends and abrupt changes of runoff and sediment load during the period between 1950 and 2005, based on monthly hydrological data. Results show that runoff and sediment load decreased from 1950 to 2005, on annual or monthly time scales. Their changes are divided into three stages: fluctuating stage (1950–1970), slowly decreasing stage (1970–1980) and accelerated decreasing stage (1980–2005). The relationship between runoff and sediment load was most significant, and it can be expressed as a linear regression function. Precipitation was one of the most important climate factors affecting runoff before 1985, and the impact of human activities on runoff decrease grew strongly after 1985. Water balance analysis of the Yellow River basin indicates that natural climate change contributed about 55.3% and human activities about 44.7% to the runoff decrease after 1986. 相似文献
9.
10.
The effect of sediment yield of a stream and the energy of sea waves on the formation of bars and their dynamics at nontidal river mouths is demonstrated. Data on variations in the hydrological regime of the Potapovskii and Bystryi branches in the Danube Delta and the morphodynamics of their bars are given. Major problems of mathematical modeling of the formation and progradation of mouth bars into the sea are discussed. An analytical expression is obtained for the shape of the foreset slope of a bar, which moves over a constant-slope seabed. The results of simulation were checked against data on the Potapovskii and Bystryi branches in the Danube Delta. 相似文献
11.
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
12.
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
13.
The hydroclimatic conditions of water runoff formation and the hydrography of Parana and Uruguay river basins in the South America are considered. A survey of the recent studies of the hydrological regime of these rivers is given. Observation data are used to evaluate the long-term average values of water runoff and suspended sediment yield in the Parana and Uruguay and their variations along the rivers. Characteristics of many-year runoff variations in the rivers were evaluated. A climate-induced increase was identified in the Parana and Uruguay water runoff, and the corresponding present-day trends in river runoff variations in both rivers were evaluated. The total water runoff and suspended sediment yield of the Parana and Uruguay into La Plata estuary were calculated. Water balance of the drainage basin of La Plata estuary was characterized. 相似文献
14.
《水文科学杂志》2013,58(3):513-525
Abstract The Water Erosion Prediction Project (WEPP) model was calibrated and evaluated for estimation of runoff and sediment yield in the data-scarce conditions of the Indian Himalaya. The inputs derived from remote sensing and geographic information system technologies were combined in the WEPP modelling system to simulate surface runoff and sediment yield from the hilly Kaneli watershed. The model parameters were calibrated using measured data on runoff volumes and sediment yield. The calibrated model was validated by producing the monthly runoff and sediment yield simulations and comparing them with data that were not used in calibration. The model was also used to make surface runoff and sediment yield simulations for each of the individual watershed elements, comprising 18 hillslopes and seven channels, and the detailed monthly results for each are presented. Although, no field data on hillslope runoff and sediment yield are currently available for the validation of distributed results produced by the model, the present investigation has demonstrated clearly the applicability of the WEPP model in predicting hydrological variables in a data-scarce situation. 相似文献
15.
Mingguo ZHENG Qiangguo CAI Qinjuan CHENG 《国际泥沙研究》2007,22(3):208-217
The relation between runoff volume and sediment yield for individual events in a given watershed receives little attention compared to the relation between water discharge and sediment yield, though it may underlie the event-based sediment-yield model for large-size watershed. The data observed at 12 experimental subwatersheds in the Dalihe river watershed in hilly areas of Loess Plateau, North China, was selected to develop and validate the relation. The peak flow is often considered as an important factor affecting event sediment yield. However, in the study areas, sediment concentration remains relatively constant when water discharge exceeds a certain critical value, implying that the heavier flow is not accompanied with the higher sediment transport capacity. Hence, only the runoff volume factor was considered in the sediment-yield model. As both the total sediment and runoff discharge were largely produced during the heavy-discharge stage, and the sediment concentration was negligibly variable during this stage, a proportional function can be used to model the relation between event runoff volume and sediment yield for a given subwatershed. The applicability of this model at larger spatial scales was also discussed, and it was found that for the Yaoxinzhuang station at the Puhe River basin, which controls a drainage area of 2264km2, a directly proportional relation between event runoff volume and sediment yield may also exist. 相似文献
16.
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
17.
1 INTRODUCTION Soil erosion at the hilly-gully region of the Loess Plateau has obvious vertical erosion zones from watershed boundary to gully edge, i.e., sheet erosion-dominated zone, rill erosion-dominated zone and shallow gully erosion-dominated zone, from top to bottom (Chen et al., 1988). Meanwhile, upslope runoff and sediment have a significant impact on the downslope erosion process. But with the limits of research methods,there is not much data to quantify upslope runoff and sedi… 相似文献
18.
This investigation showed that urban stormwater runoff provides a significant amount of petrogenic material to receiving waters and sediments. A characteristic hydrocarbon ‘fingerprint’ for sediments and particulate matter in the Hillsborough Reservoir, Hillsborough River and upper Hillsborough Bay was provided. Determination of source material for petroleum contamination in stormwater runoff and river sediment indicated that crankcase oil was a primary contributor to sediment hydrocarbon contamination. A comparison of sediment hydrocarbons with hydrocarbons from stormwater runoff showed that the most probable source of crankcase oil-like petrochemicals found in sediment was the stormwater runoff.A comparison of hydrocarbon composition in suspended particulate matter with that of accumulated bottom sediments in the reservoir, river and bay, during a non-storm period and rising tide showed no resuspension and upriver transport of petroleum contaminated bay sediment. No special influence of the bay upon the lower river was observed relative to hydrocarbon tracers, indicating that most contaminated sediment transport was downriver during storm events. Additional studies should be performed over various tidal cycles and storm events incorporating sediment cores, sediment grain size analysis and hydrocarbon characterization at more closely spaced stations near the river mouth to address adequately the question of specific hydrocarbon pollution sources, rate of petroleum influx and persistence of petrochemical contaminants in the sediment. 相似文献
19.
D. V. Magritskii 《Water Resources》2011,38(6):709-719
Data of network and expedition measurements and information about water management arrangements were used to study in detail
the peculiarities of along-channel and long-term variations in the major characteristics of suspended sediment runoff in the
lower reach and the delta of the Kuban River. For characteristics periods, the annual volumes of actual and estimated sediment
runoff and the contribution of economic activity in its variations are evaluated and possible changes in sediment runoff characteristics
in the XXI century are forecasted. The specific features, values, and causes of sediment runoff transformation in Kuban delta
in the past and the present are analyzed; sediment balance in the delta is calculated. 相似文献
20.
Runoff generation and sediment yield on homogeneous dune slopes: scale effect and implications for analysis 总被引：1，自引：0，他引：1
Giora J. Kidron 《地球表面变化过程与地形》2011,36(13):1809-1824
Data concerning runoff and sediment yield in arid zones is of prime importance for hydrologists, geomorphologists, pedologists, ecologists and landscape engineers. For data comparison and extrapolations, runoff and sediment yield are often presented in mass per unit area. Runoff and sediment yield collected on dune slopes over a wide range of plot sizes during 1990–1994 in the Negev Desert, Israel, showed that the contributing area was mainly confined to a narrow belt at the bottom of the slopes. It was therefore hypothesized that the very short rain bursts, capable of runoff generation, may result in a scale effect (SE). Indeed, average duration of duration of consecutive medium and high rain intensities which are potentially above the surface infiltration rate ranged between 2.2 and 3.0 minutes, implying that flow connectivity is largely limited. Based on the intermittent character of the rain spells capable of runoff generation it is argued that SE is an inherent outcome of the rain properties. Yet, it is further argued that the magnitude of the SE is surface‐dependent. As a result, it is argued that the conventional way for runoff and sediment yield presentation as mass per unit area implies theoretical misconceptions and may cause gross overestimation in extrapolation and the presentation of runoff and sediment yield in mass per unit width of the slope is suggested. The accuracy of the two extrapolation methods are compared to the actual runoff and sediment yield collected in the field. The data show that extrapolation based on runoff (or sediment) yield per plot width deviates from the actual amounts collected by a factor of 1·1 to 1·3 only while deviating by a factor of 4·2 to 5·6 and 10·7 to 11·8 if the extrapolation is based on large and small plots, respectively. Theoretical and practical reasons for presentation of runoff and sediment yield as mass per unit width are discussed. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献