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1.
Throughout the history of China, the Yellow River has been associated with flood disasters and changes in the course of its lower reaches because of sedimentation. From 602 B.C. to 1949 the river experienced 1593 levee bursts, flooding vast areas, and claiming millions of human lives. The river shifted its main course by avulsion 26 times with the apex around Zhengzhou, resulting in devastating calamities and numerous old channels. Training of the Yellow River has a history of more than 3000 yr. Levee construction has been the major strategy for flood control. Two extremely different strategies has been proposed and practiced in the past 2000 yr, i.e. the "wide river and depositing sediment" strategy and the "narrow river and scouring sediment" strategy. This paper analyzes the levee breaches and flood disasters in the past 2000 yr and compares the results of the two extremely different strategies. The "narrow river and scouring sediment" strategy has only short term effects on levee breach control and flood mitigation. The "wide river and depositing sediment" strategy can essentially mitigate flood disasters and reduce levee breaches for a long term period of time. The "wide river and depositing sediment" strategy has been used and no levee breach has occurred in the past 67 yr, which has been the only periods of more than 50 yr with no levee breaches in the history of the Yellow River since 700 A.D.Modern flood and sedimentation management methods have also been introduced, and the strategy of applying the ' "widen the river and enhance the levees" approach for the upper and lower reaches management is proposed.  相似文献   

2.
The method of multiple regression is used to analyze the influences of flood events from the coarse sediment producing areas on the channel siltation and fluvial process of the lower Yellow River based on the flood events from 1950 to 1985. The results showed that the flood events from the coarse sediment producing areas carry larger amounts of sediment load and coarser particle sizes than from other source areas, which increases deposition in the lower river channel. And there exist good correlations between channel siltation of the lower reaches of the Yellow River and the coming water and sediment of flood events from the coarse sediment producing areas. Through these correlations, the amounts of sediment deposition in the lower river channel could be roughly estimated based on the runoff and sediment load of flood events from the coarse sediment producing areas. The sediment deposition caused the fluvial process. There exists a complex response of channel form change to the coming water and sediment load of flood events from the coarse sediment producing areas. When the sediment concentration is smaller than 200kg/m3, the ratio between wide-depth ratio after flood and wide-depth ratio before flood((B/h)a / (B/h)b) will increase with the increase of the maximum sediment concentration; when the sediment concentration is near 200kg/m3, (B/h)a / (B/h)b reaches the maximum value; and when the sediment concentration reaches the limits of hyperconcentrated flow, (B/h)a / (B/h)b will decrease with the increase of the maximum sediment concentration. Generally, flood events from the coarse sediment producing areas made channel form of the lower Yellow River deeper and narrower, but a large amount of sediment deposition simultaneously occurs. So, the impacts of flood events from the coarse sediment producing areas on the channel of the lower Yellow River are lessened.  相似文献   

3.
1 INTRODUCTION Large-scale flood disasters have frequently occurred in the middle Yangtze River since the 1990抯. The Jingjiang River and Dongting Lake (Fig. 1) comprise the most serious area of flood disasters. The main characteristic of recent disasters is low discharge and high water stage. Recent research has begun to pay more attention to the important role of sediment deposition (Li and Ni, 1998). Though the Yangtze River is not an overloaded river, the amount of sediment trans…  相似文献   

4.
The Three Gorges Project is one of the largest hydro-projects in the world and has drawn many debates inside China and abroad. The major concern is that sediment load from the river basin may eventually fail the functions of the project for flood control and power generation. To reduce sedimentation in the reservoir, watershed management has been adopted. However, there is limited information regarding the effectiveness of various control measures such as terracing and afforestation on a watershed scale. The Jialing River, a main tributary of the Yangtze River, contributes approximately 25% of the total sediment load in the main river but only represents 8% of the whole basin area. There have been various land use patterns and extensive human activities for thousands of years in the Jialing River watershed. Based on analysis of the major factors affecting erosion in the Jialing River watershed, the main watershed management strategies (afforestation, farming and engineering practice) are illustrated, and their effects on the reduction of sediment and runoff are studied in detail. The sediment budget of the watershed shows that 1/3 of the sediment yield is trapped by the erosion control measures (afforestation and farming) on the slope, 1/3 is trapped by the reservoirs, ponds and dams within the watershed, and only about 1/3 is transported into the Yangtze River, which will affect the Three Gorges Project.  相似文献   

5.
Flood control of the Yangtze River is an important part of China’s national water security.In July 2020,due to continuous heavy rainfall,the water levels along the middle-lower reaches of the Yangtze River and major lakes constantly exceeded the warning levels,in which Taihu Lake exceeded its highest safety water level and some stations of Poyang Lake reached their highest water levels in its history.In August 2020,another huge flood occurred in the Minjiang River and the Jialing River in the upper Yangtze River,and some areas of Chongqing Municipality and other cities along the rivers were inundated,resulting in great pressure on flood control and high disaster losses.The 2020 Yangtze River flood has received extensive media coverage and raised concerns on the roles of the Three Gorges Dam and other large reservoirs in flood control.Here we analyze the changes in the pattern of the Yangtze River flood control by comparing the strategies to tackle the three heavy floods occurring in 1954,1998,and 2020.We propose that the overall strategy of the Yangtze River flood control in the new era should adhere to the principle of"Integration of storage and drainage over the entire Yangtze River Basin,with draining floods downstream as the first priority"by using both engineering and non-engineering measures.On the basis of embankments,the engineering measures should use the Three Gorges Dam and other large reservoirs as the major regulatory means,promote the construction of key flood detention areas,keep the floodways clear,and maintain the ecosystem services of wetlands and shoals.In terms of non-engineering measures,we should strengthen adaptive flood risk management under climate change,standardize the use of lands in flood detention areas,give space to floods,and promote the implementation of flood risk maps and flood insurance policies.The ultimate goal of this new flood control system is to enhance the adaptability to frequent floods and increase the resilience to extreme flood disasters.  相似文献   

6.
Based on long-term measurements at three gauging stations, Toudaoguai, Fugu and Hequ, and one meteorological station, this article discusses the features of discharge (Q) and sediment concentration (Cs) of a river reach of the Yellow River with a reservoir located in the Loess Plateau. The impacts of the local sub-watershed between Toudaoguai and Fugu gauging stations on sediment budget to the Yellow River have been analyzed. In addition, the deposition processes in the Tianqiao Reservoir have been investigated. Results show over 80% of the precipitation that falls in the local subwatershed is unable to contribute to the Yellow River runoff process. It is found that the annualmaximum sediment concentration is usually less than 30 kg/m^3 during flood seasons at Toudaoguai Gauging Station, but the sediment concentration varies dramatically at Fugu Gauging Station. About 35% of the sediment eroded in the sub-watersheds between Toudaoguai and Fugu gauging stationswas produced from the Huangfuchuan sub-watershed which has a drainage area accounting only for 10% of the drainage area between Toudaoguai and Fugu gauging stations. The Tianqiao Reservoir generally has deposition during the summer flood season, and scouring during the non-flood season.On average, over 85% of deposited sediment in the reservoir occurs in the 12 km long lower reservoir reach. The volume of annual deposition in the reservoir mainly depends on the volume of water from the local region between Hequ and Fugu gauging stations.  相似文献   

7.
This paper summarizes the latest developments, future prospects, and proposed countermeasures of reservoir sedimentation and channel scour downstream of the Three Gorges Reservoir (TGR) on the Yangtze River in China. Three key results have been found.(1) The incoming sediment load to the TGR has been significantly lower than expected.(2) The accumulated volume of sediment deposition in the TGR is smaller than expected because the overall sediment delivery ratio is relatively low, and the deposition in the near-dam area of the TGR is still developing.(3) River bed scour in the river reaches downstream of the Gezhouba Dam is still occurring and channel scour has extended to reaches as far downstream as the Hukou reach. Significantly, sedimentation of the TGR is less problematic than expected since the start of operation of the TGR on the one hand;on the other hand, the possible increases in sediment risks from dependence on upstream sediment control, deposition in the reservoir, and scour along middle Yangtze River should be paid more attention.(1) Sediment trapped by dams built along the upper Yangtze River and billion tons of loose materials on unstable slopes produced by the Wenchuan Earthquake could be new sediment sources for the upper Yangtze River. More seriously, possible release of this sediment into the upper Yangtze River due to new earthquakes or extreme climate events could overwhelm the river system, and produce catastrophic consequences.(2) Increasing sediment deposition in the TGR is harmful to the safety and efficiency of project operation and navigation.(3) The drastic scour along the middle Yangtze River has intensified the down-cutting of the riverbed and erosion of revetment, it has already led to increasing risk to flood control structures and ecological safety. It is suggested to continue the Field Observation Program, to initiate research programs and to focus on risks of sedimentation.  相似文献   

8.
The equilibrium relations for water and sediment transport refer to the relative balance of sediment transport and the relative stability of river courses formed by the automatic adjustment of riverbeds.This is the theoretical basis for the comprehensive management of sediment in the Yellow River.Based on the theories of sediment carrying capacity and the delayed response of riverbed evolution,in this study,the equilibrium relations for water and sediment transport in the Yellow River are established.These relations include the equilibrium relationships between water and sediment transport and bankfull discharge in the upper and lower Yellow River and between water and sediment transport and the Tongguan elevation in the middle Yellow River.The results reveal that for the Ningmeng reach,the Tongguan reach,and the lower Yellow River,erosion and deposition in the riverbeds are adjusted automatically,and water and sediment transport can form highly constrained equilibrium relationships.These newly established equilibrium relationships can be applied to calculate the optimal spatial allocation scheme for sediment in the Yellow River.  相似文献   

9.
1. INTRODUCTIONThe Yellow River is a heavily sediment--laden river. Floods at Hyperconcentrationso f sediment (hereinafter simply referred to as hyperconcentrated flood) frequently occurring in the main river and its tributaries possess different characteristics of sedimenttransport. Sometimes they cause severe deposition whereas at other times they are capable of carrying substantial amount of sediment over long distances. The study on the lawof sediment transport is of significance to …  相似文献   

10.
INTRODUCTIONIn the past decade frequently occurring floods claimed thousands of lives and caused economic loss of billions US dollars. Among them the Mississippi River flood in 1993, the Rhine River flood in 1995, the Yangtze River flood in 1998, the Haihe River flood in 1996, and the storm surges in Bangladesh in 1991 are the most devastating. It is evident that both the frequency and intensity of flooding are increasing.The first International Symposium on Flood Defence in Sep. 20…  相似文献   

11.
Wind-blown sand is one of the key factors affecting the evolution of sediment transport,erosion,and deposition in rivers crossing desert areas.However,the differences and complex variations in the spatial and temporal distribution of the underlying surface conditions are seldom considered in research on the river inflow of wind-blown sand over a long time period.The Yellow River contains a large amount of sediment.The Ningxia-Inner Mongolia reach of the Yellow River was selected as the research ...  相似文献   

12.
The southeastern portion of the Yangtze River Estuary (or Yangtze Estuary) was considered to be the deposition center and the mudbank of the Yangtze River Delta.As the fluvial sediment supply began to decline in the 1980s and the reduction accelerated after the completion of the Three Gorge Dam in 2003,more fluvial sediment was trapped decreasing the suspended sediment concentration (SSC) environment in the river mouth area.Moreover,the accretion rate of the mudbank has slowed down in recent dec...  相似文献   

13.
Runoffs in the Yellow River and Yangtze River basins,China,have been changing constantly during the last half century.In this paper,data from eight river gauging stations and 529 meteorological stations,inside and adjacent to the study basins,were analyzed and compared to quantify the hydrological processes involved,and to evaluate the role of human activities in changing river discharges.The Inverse Distance Weighted(IDW)interpolation method was used to obtain climatic data coverage from station observations.According to the runoff coefficient equation,the effect of human activities and climate can be expressed by changes in runoff coefficients and changes in precipitation,respectively.Annual runoff coefficients were calculated for the period 1950-2008,according to the correlation between respective hydrological series and regional precipitation.Annual precipitation showed no obvious trend in the upper reaches of the Yellow River but a marked downward trend in the middle and downstream reaches,with declines of 8.8 and 9.8 mm/10 a,respectively.All annual runoff series for the Yellow River basin showed a significant downward trend.Runoff declined by about 7.8 mm/10 a at Sanmenxia and 10.8 mm/10 a at Lijin.The series results indicated that an abrupt change occurred in the late 1980s to early 1990s.The trend of correlations between annual runoff and precipitation decreased significantly at the Yellow River stations,with rates ranging from 0.013/10 a to 0.019/10 a.For the hydrologic series,all precipitation series showed a downward trend in the Yangtze River basin with declines ranging from about 24.7 mm/10 a at Cuntan to 18.2 mm/10 a at Datong.Annual runoff series for the upper reaches of the Yangtze River decreased significantly,at rates ranging from 9.9 to 7.2 mm/10 a.In the middle and lower reaches,the runoff series showed no significant trend,with rates of change ranging from 2.1 to 2.9 mm/10 a.Human activities had the greatest influence on changes in the hydrological series of runoff,regardless of whether the effect was negative or positive.During 1970-2008,human activities contributed to 83% of the reduction in runoff in the Yellow River basin,and to 71% of the increase in runoff in the Yangtze River basin.Moreover,the impacts of human activities across the entire basin increased over time.In the 2000s,the impact of human activities exceeded that of climate change and was responsible for 84% of the decrease and 73% of the increase in runoff in the Yellow River and Yangtze River basins,respectively.The average annual runoff from 1980 to 2008 fell by about 97%,83%,83%,and 91%,compared with 1951-1969,at the Yellow River stations Lanzhou,Sanmenxia,Huayuankou and Lijin,respectively.Most of the reduction in runoff was caused by human activities.Changes in precipitation also caused reductions in runoff of about 3%,17%,17%,and 9% at these four stations,respectively.Falling precipitation rates were the main explanation for runoff changes at the Yangtze River stations Cuntan,Yichang,Hankou,and Datong,causing reductions in runoff of 89%,74%,43%,and 35%,respectively.Underlying surface changes caused decreases in runoff in the Yellow River basin and increases in runoff in the Yangtze River basin.Runoff decreased in arid areas as a result of increased water usage,but increased in humid and sub-humid areas as a result of land reclamation and mass urbanization leading to decreases in evaporation and infiltration.  相似文献   

14.
Small runoff, large sediment load, and incompatible relationship of flow and sediment load are very important characteristics of the Yellow River. They are also the crux of the most prominent problems of the Yellow River. To solve these problems, the regimes of flow and sediment load have to be improved by increasing water, reducing sediment load, and by using reservoirs to regulate flow and sediment load. The results of experiments for regulating the flow and sediment load in the last three years by the Xiaolangdi Reservoir have indicated that this measure is a realistic and effective way to mitigate the prominent problems in flood control of the Lower Yellow River at present and in the near future. However, the regulation system is still imperfect. It is advisable to speed up the pace of research and construction of the system for regulating flow and sediment load.  相似文献   

15.
Estuarine environments are influenced by both river flows and oceanic tidal movement of water, sediment, and nutrients, often forming ecosystems that are rich in resources and biodiversity. The Yellow River once carried the world’s largest sediment load, but artificial structures have transformed its hydrodynamic processes. An annual Water-Sediment Regulation Scheme(WSRS) was introduced to flush accumulated sediment from the Xiaolangdi Reservoir, which provides flood control and water storage.Ho...  相似文献   

16.
I. CHAncEL CHANGal m THE FLOODED AREA ArVER BREACHING AT TONGWAXIANG AND THEIR IMPACTSIn mid--June of 1855 a great flood occurred in the lower reaches of the Yellow River. The findmainly came down from the main stem of the river and itS tributary Qinhe River. In the meantimethe riparian area of the Yellow River had just been subjected to a heavy rain, and large amountS of water from mountains and hills were flowing into the river and lakes were also full. The Weis…  相似文献   

17.
This paper uses monthly streamflow, suspended sediment concentration, and meteorological data to examine the impact of human activity and climate change on streamflow and sediment load in the Pearl River basin from the 1950s to the 2000s. The influences of climate change and human activities on hydrological processes were quantitatively evaluated using the Mann–Kendall abrupt change test and power rating curves. The results showed that:(1) abrupt changes and turning points in streamflow occurred in 1963, 1983, and 1991 which were found to be consistent with global ENSO events and volcanic eruptions. However, abrupt changes in sediment load showed significant spatial differences across the Pearl River basin. For the Xijiang River, an abrupt change in sediment load occurred in 2002, and after 2007 the change becomes significant at the 95% confidence level. At Beijiang and Dongjiang, abrupt changes in sediment load occurred in 1998 and 1988, respectively.(2) The time series of sediment load data was divided into four periods according to abrupt changes. The contribution of climate change and human activities is different in the different rivers. For the Xijiang River, compared with the first period, climate change and human activities contributed 83% and 17%, respectively, to the increasing sediment load during the second period. In the third period, the variation of sediment load followed a decreasing trend. The contribution from climate change and human activities also changed to t236% and -136%, respectively. In the fourth period, climate change and human activities contributed -32% and t132%, respectively. Meanwhile, For the Beijiang River, climate change and human activities contributed 90% and 10% in the second period, the contribution of climate change increased to t115% and human activities decreased to -15% in the third period. In the fourth period, the value for climate change decreased to t36% and human activities increased to t64%. For the Dongjiang River, the contribution of human activities was from 74.5% to 90%, and the values for climate change were from 11% to 25%. Therefore, the effect of human activity showed both spatial and temporal differences, and it seems likely that the decreased sediment load will continue to be controlled mainly by human activities in the future.  相似文献   

18.
Concentrations of suspended particle material(SPM), dissolved silicate(DSi), biogenic silica(BSi), phytoliths(plant produced siliceous microscopic structures), and other parameters were analyzed to examine the influence of both natural processes and human activities on silica delivery to the estuary of the Huanghe River(Yellow River). Our results indicate that the concentrations of DSi in the river decreased significantly since 1986. Approximately 34% of dissolved silica was trapped in the basin between 1986 and 2010 due to a reduction of soil erosion. Phytoliths comprised 67.2%–96.3% of BSi, with the smoothing bar type being the dominant form. Concentrations of BSi are significantly higher in the Huanghe River compared to other major rivers throughout the world due to its high sediment yield. We also found that the ratios of BSi/(BSi+DSi) and BSi/SPM were approximately 0.5 and 0.003 at Lijin near the river mouth, indicating that BSi carried in suspension by the Huanghe River was an important component of the rivers silica load. Significant amounts of BSi were also composed of phytoliths in Bohai Sea sediments near the Huanghe River estuary with the smoothing bar form again being the most abundant. The relatively high specific fluxes of BSi in the Huanghe River reflect its high turbidity and high erosion rates in the basin. The high sediment load originating on the Loess Plateau is likely responsible for the higher BSi flux, in agreement with a general trend of increasing BSi flux with increasing sediment flux in global river systems. This study demonstrates that BSi transported by rivers can be composed largely of phytoliths originating from the erosion of topsoils. The flux of phytoliths in river's suspended sediment load may therefore represent a significant contribution to the biogeochemical cycle of silica in coastal waters.  相似文献   

19.
Wind-blown sand is one of the key factors affecting the evolution of sediment transport,erosion,and deposition in rivers crossing desert areas.However,the differences and complex variations in the spatial and temporal distribution of the underlying surface conditions are seldom considered in research on the river inflow of wind-blown sand over a long time period.The Yellow River contains a large amount of sediment.The NingxiaeInner Mongolia reach of the Yellow River was selected as the research area of the current study.The reach flows out of Heishanxia and then flows through the Tengger,Hedong,Ulan Buh,and Kubuqi Deserts.In the current study,the wind speed,vegetation coverage,and sand matter on the river basin's surface were analyzed from the perspectives of the river basin surface and riverbank line.The vegetation coverage of the river basin's surface was calculated using the normalized difference vegetation index.Based on the types of sand matter,vegetation coverage,and other underlying surface conditions,the loose particle sediment transport efficiency was determined,the Lettau and Lettau formula for the sediment transport rate was modified,a surface wind-erosion sand flux model was established,and the amount of wind-blown sand transported into the NingxiaeInner Mongolia reach was calculated.The results show that,from 1981 to 2014,the annual average amount of wind-blown sand transported into the main stream and tributaries of the NingxiaeInner Mongolia reach of the Yellow River were 7,310,000 and 13,190,000 t,respectively.The ShizuishaneBayangole reach received 51%of the total wind-blown sand that transported into the main stream,while the tributaries in the Shidakongdui area were the most important source wind-blown sand,providing 74%of the total windblown sand inflow from the tributaries.In recent years,the amount of sand transported into the river of the mainstream and tributaries of the NingxiaeInner Mongolia reach of the Yellow River has significantly decreased from 1981 to 2002,particularly in 1993e2002,which is mainly the result of the weakening wind speed,increasing vegetation coverage,and embankment construction.More specifically,environmental protection policies led by the government,such as“returning farmland to forest”,have played an important and positive role.Therefore,when regulating the water and sediment in the NingxiaeInner Mongolia reach of the Yellow River,the issue of wind-blown sand deposition into the river should be fully considered in water and sediment regulation.  相似文献   

20.
As economic development upstream in the Yangtze River basin has progressed in recent decades,the demand for sediment has rapidly increased and contributed to an expansion in sediment excavation that may affect the river’s stability and navigation safety.In the current study,the distribution of gravel mining in the upstream reach of the Yangtze River was investigated using field measurements obtained from2008 to 2017.An experimental investigation was then done to analyze the bed load behavior in ...  相似文献   

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