scholarly journals Evolution of Flood Regulation Capacity for a Large Shallow Retention Lake: Characterization, Mechanism, and Impacts

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2853
Author(s):  
Zhandong Sun ◽  
Qun Huang ◽  
Tom Lotz
Keyword(s):  
Water Level ◽  
Wavelet Decomposition ◽  
Comprehensive Evaluation ◽  
High Water ◽  
Dongting Lake ◽  
Flood Peak ◽  
The Three Gorges ◽  
Key Factor ◽  
Flood Regulation ◽  
Near Future

The retention lake often plays an important role in flood mitigation through the water storage and the lake–river interactions. However, the evolution of real-time flood regulation capacity remains poorly characterized. Using wavelet decomposition and flood peak removing ratios, this study presents a comprehensive evaluation of the characterization, mechanism, and impacts of the flood regulation capacity in Dongting Lake. The results indicate that the change of flood regulation effect of the lake can be well reflected by the multi-year changes in the variances of the inflow and outflow runoffs. The wavelet decomposition indicates that the flood regulation of the lake is mainly functioned on the high-frequency floods with durations less than 32 days. The average yearly flood peak removing ratios range from 0.13 to 0.56, but no significant tendency changes on the effect of the flood regulation capacity has happened during the study period. The changes in maximum regulation volume reveal that the flood regulation of the Dongting Lake is mainly a passive process decided by the complex river–lake relationship and the interactions among different processes of discharge and sediment. The impacts from the large volume reduction caused by sedimentation in the lake is compensated by the increased flood controlling water level, which in turn have resulted in the new phenomenon of “normal discharge, high water level and disaster” in the lake regions after the 1990s. The significant impacts on the lake–river relationship caused by the sediment reallocation from the operation of the Three Gorges Reservoir (TGR) have further changed the hydrological regimes between the lake and the Yangtze River. Influenced by the new lake-river interaction pattern the discharge passing capacity downstream the outlet of the lake is becoming a key factor that affects the flood regulation capacity, which is leading to a shift of the flood pressures from the lake region to the downstream of Yangtze in the near future.

scholarly journals The influence of Three Gorges Reservoir high water level on the rainfall runoff

2018 ◽  
Vol 246 ◽  
pp. 01007
Author(s):  
Biqiong Wu ◽  
Wei Zheng ◽  
Xinkai Ren ◽  
Tao Xu ◽  
Xiao Guo
Keyword(s):  
Water Level ◽  
Three Gorges Reservoir ◽  
Reference Value ◽  
High Water ◽  
Three Gorges ◽  
Rainfall Runoff ◽  
Flood Peak ◽  
High Water Level ◽  
Three Gorges Region ◽  
Unit Hydrographs

After Three Gorges Reservoir building up, the natural river course and the near hillside inside the backwater region are inundated to form a fairly wide man-made lake which affects the hydrological characteristics and floodwater transmission to different degrees. When the reservoir impound to high water level, the conflux time is obviously shortened, the flood-peak discharge increase, and the peak type became sharper. The change of runoff yield and concentration makes the forecast scheme unable to be applied well. Based on the practice of Three Gorges Reservoir operation, the rainfall-runoff characteristics of the backwater region under the condition of high water level are analysed and summarized, then a set of unit hydrographs suitable for rainfall-runoff calculation are recalibrated, which has great reference value for hydrological forecasting of Three Gorges region.

scholarly journals Quantifying the effects of channel change on the discharge diversion of Jingjiang Three Outlets after the operation of the Three Gorges Dam

2016 ◽  
Vol 47 (S1) ◽  
pp. 161-174 ◽  
Author(s):  
Yanyan Li ◽  
Guishan Yang ◽  
Bing Li ◽  
Rongrong Wan ◽  
Weili Duan ◽  
...  
Keyword(s):  
Water Level ◽  
Yangtze River ◽  
Flood Control ◽  
Dongting Lake ◽  
Three Gorges Dam ◽  
Three Gorges ◽  
Channel Change ◽  
Channel Changes ◽  
The Three Gorges ◽  
The Three Gorges Dam

The Jingjiang Three Outlets (JTO) are the water-sediment connecting channels between the Yangtze River and the Dongting Lake. The discharge diversion of the JTO plays a dominant role in the flood control of the middle–lower Yangtze River, Dongting Lake evolution, and ecological environment. After the operation of the Three Gorges Dam (TGD), the river channels downstream experienced dramatic channel changes. To study the influences of the channel change on the discharge diversion, the authors analyzed the channel changes by water level–discharge rating curves and cross-sectional channel profiles in 1980–2014. Hence, changes in the water level with the same discharge and the decline of discharge diversion at the JTO were noted. Channel incision caused the water level with the same discharge to greatly decrease in the upper Jingjiang River. The water level with the same discharge significantly increased at the JTO as a result of the channel deposition. The channel changes contributed approximately 37.74% and 76.36%, respectively, to the amount and ratio of discharge diversion decreases after the TGD operation. The channel changes serve as the primary factor in facilitating the decrease in the discharge diversion ratio, but not the main factor for the decreased amount of the discharge diversion.

Impact of the Three Gorges Project's Operation on Low Water Level in Changsha Reach

2014 ◽  
Vol 926-930 ◽  
pp. 4250-4253
Author(s):  
Chang Ying Chen ◽  
Yi Nong Chen ◽  
Xing Nong Zhang ◽  
Yao Ge
Keyword(s):  
Water Level ◽  
Dongting Lake ◽  
Three Gorges ◽  
Appearance Time ◽  
The Three Gorges ◽  
The Impact

In view of the seriously drought and the condition that the water level in Changsha reach continuously break the historical lowest records in recent years, the variation law of low water level in Changsha reach and the impact of the Three Gorges Projects operation on low water level were studied. The results show that the water level in the same discharge and the monthly averaged water level and the lowest water level all decrease year by year, and the appearance time of the lowest water level in recent years is earlier. The lowest water level in Changsha reach isnt much connected with the variation of water level in Dongting lake, but connected with the riverbed undercutting caused by the operation of hydro-junction and the excavation of sand. The appearance time advance of the lowest water level is connected with the Three Gorges Projects operation.

Lake and inland dunes as interconnected Systems: The story of Lake Tresssee and an adjacent dune field (Schleswig-Holstein, North Germany)

The Holocene ◽  
2020 ◽  
pp. 095968362098168
Author(s):  
Christian Stolz ◽  
Magdalena Suchora ◽  
Irena A Pidek ◽  
Alexander Fülling
Keyword(s):  
Water Level ◽  
Bronze Age ◽  
Environmental Changes ◽  
High Water ◽  
Alluvial Fan ◽  
Water Levels ◽  
Lake Area ◽  
Dune Field ◽  
The North ◽  
Sand Drift

The specific aim of the study was to investigate how four adjacent geomorphological systems – a lake, a dune field, a small alluvial fan and a slope system – responded to the same impacts. Lake Tresssee is a shallow lake in the North of Germany (Schleswig-Holstein). During the Holocene, the lake’s water surface declined drastically, predominately as a consequence of human impact. The adjacent inland dune field shows several traces of former sand drift events. Using 30 new radiocarbon ages and the results of 16 OSL samples, this study aims to create a new timeline tracing the interaction between lake and dunes, as well, as how both the lake and the dunes reacted to environmental changes. The water level of the lake is presumed to have peaked during the period before the Younger Dryas (YD; start at 10.73 ka BC). After the Boreal period (OSL age 8050 ± 690 BC) the level must have undergone fluctuations triggered by climatic events and the first human influences. The last demonstrable high water level was during the Late Bronze Age (1003–844 cal. BC). The first to the 9th century AD saw slightly shrinking water levels, and more significant ones thereafter. In the 19th century, the lake area was artificially reduced to a minimum by the human population. In the dunes, a total of seven different phases of sand drift were demonstrated for the last 13,000 years. It is one of the most precisely dated inland-dune chronologies of Central Europe. The small alluvial fan took shape mainly between the 13th and 17th centuries AD. After 1700 cal. BC (Middle Bronze Age), and again during the sixth and seventh centuries AD, we find enhanced slope activity with the formation of Holocene colluvia.

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