Observation and Simulation of Floodwater Intrusion and Sedimentation in the Shichikashuku Reservoir

Umeda, Makoto; Yokoyama, Katsuhide; Ishikawa, Tadaharu

doi:10.1061/(asce)0733-9429(2006)132:9(881)

Cited by 27 publications

(18 citation statements)

References 29 publications

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“…The density difference between inflow and ambient water may arise from both temperature differences and variations in solute concentrations (Chen et al, 2006;Chung et al, 2009;An et al, 2012;An and Julien, 2014), and the inflow can be a tributary from an upstream river, transferred water from another reservoir or contaminant spill from a location (Gu and Chung, 2003;de Cesare et al, 2006;Umeda et al, 2006). An overflow (Fig.…”

Section: Introductionmentioning

confidence: 99%

Effect of thermal stratification on interflow travel time in stratified reservoir

Zhang

Shi

et al. 2015

J. Zhejiang Univ. Sci. A

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This study is focused on the impact of thermal stratification on interflow travel time. A quantitative relation between buoyancy frequency and interflow travel time is theoretically derived based on the Bernoulli principle of energy conservation. Experiments and numerical simulations are carried out to validate the applicability of the proposed relation. For experiments, interflow movement is successfully detected in a small-depth water tank by releasing a denser flow into a temperature stratification environment. For numerical simulations, a vertical 2D renormalization group (RNG) k- model is developed to simulate the interflow. The results both of the experiments and of the numerical simulations verify our proposed theory. The derived analytic relation is useful for the prediction of contaminant travel time in reservoirs and in assisting pollution control.

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Section: Introductionmentioning

confidence: 99%

Effect of thermal stratification on interflow travel time in stratified reservoir

Zhang

Shi

et al. 2015

J. Zhejiang Univ. Sci. A

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“…Turbidity currents can play an important role in the management and initial design of reservoirs (Chikita, 1989(Chikita, , 1990Fan and Morris, 1992;Umeda et al, 2000Umeda et al, , 2006De Cesare et al, 2001). Sediment deposition by turbidity currents affects their storage capacity, which can have significant strategic importance in locations affected by rapid siltation, such as the large reservoirs along the Yellow River in China (Hu et al, 2012;Wei et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

How are subaqueous sediment density flows triggered, what is their internal structure and how does it evolve? Direct observations from monitoring of active flows

Talling

Paull

Piper

2013

Earth-Science Reviews

211

184

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Subaqueous sediment density flows are one of the volumetrically most important processes for moving sediment across our planet, and form the largest sediment accumulations on Earth (submarine fans). They are also arguably the most sparely monitored major sediment transport processes on our planet. Significant advances have been made in documenting their timing and triggers, especially within submarine canyons and delta-fronts, and freshwater lakes and reservoirs, but the sediment concentration of flows that run out beyond the continental slope has never been measured directly. This limited amount of monitoring data contrasts sharply with other major types of sediment flow, such as river systems, and ensure that understanding submarine sediment density flows remains a major challenge for Earth science. The available monitoring data define a series of flow types whose character and deposits differ significantly. Large (N 100 km 3 ) failures on the continental slope can generate fast-moving (up to 19 m/s) flows that reach the deep ocean, and deposit thick layers of sand across submarine fans. Even small volume (0.008 km 3 ) canyon head failures can sometimes generate channelised flows that travel at N 5 m/s for several hundred kilometres. A single event off SE Taiwan shows that river floods can generate powerful flows that reach the deep ocean, in this case triggered by failure of recently deposited sediment in the canyon head. Direct monitoring evidence of powerful oceanic flows produced by plunging hyperpycnal flood water is lacking, although this process has produced shorter and weaker oceanic flows. Numerous flows can occur each year on river-fed delta fronts, where they can generate up-slope migrating crescentic bedforms. These flows tend to occur during the flood season, but are not necessarily associated with individual flood discharge peaks, suggesting that they are often triggered by delta-front slope failures. Powerful flows occur several times each year in canyons fed by sand from the shelf, associated with strong wave action. These flows can also generate up-slope migrating crescentic bedforms that most likely originate due to retrogressive breaching associated with a dense near-bed layer of sediment. Expanded dilute flows that are supercritical and fully turbulent are also triggered by wave action in canyons. Sediment density flows in lakes and reservoirs generated by plunging river flood water have been monitored in much greater detail. They are typically very dilute (b 0.01 vol.% sediment) and travel at b 50 cm/s, and are prone to generating interflows within the density stratified freshwater. A key objective for future work is to develop measurement techniques for seeing through overlying dilute clouds of sediment, to determine whether dense near-bed layers are present. There is also a need to combine monitoring of flows with detailed analyses of flow deposits, in order to understand how flows are recorded in the rock record. Finally, a source-to-sink approach is needed because the character of subm...

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“…이러한 탁 수모델링 연구는 저수지내로 유입된 탁수의 밀도류 거동 과 시 공간적인 분포를 예측하여 탁수 장기화에 대한 원인 기작을 해석하고, 효과적인 제어대책과 최적의 댐 운영 관 리방안을 제시하는데 초점을 두고 있다 (정세웅 등, 2008;Chung et al, 2009;Gelda and Effler, 2007b;Umeda et al, 2006;Yajima et al, 2006). 그러나 탁수모델링은 저수지 의 성층현상, 탁수의 밀도류 거동, 그리고 다양한 크기의 부유입자의 침강특성 등 물리적 기작의 복잡성과 실측자 료의 제한성 때문에 모의결과에 대한 신뢰도 확보에 많은 어려움이 있었다 (Chung et al, 2009).…”

Section: 나타났다 이러한 이격현상은 저수지로 유입하는 Ss 부하량 산정에 있어 유의할 만한 오차로 작용하였으며 Q-unclassified

Uncertainty of Discharge-SS Relationship Used for Turbid Flow Modeling

Chung¹,

Lee²,

Lee³

et al. 2011

Journal of Korea Water Resources Association

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The relationship between discharge (Q) and suspended sediment (SS) concentration often is used for the estimation of inflow SS concentration in reservoir turbidity modeling in the absence of actual measurements. The power function, SS=aQ b , is the most commonly used empirical relation to determine the SS load assuming the SS flux is controlled by variations of discharge. However, Q-SS relation typically is site specific and can vary depending on the season of the year. In addition, the relation sometimes shows hysteresis during rising limb and falling limb for an event hydrograph. The objective of this study was to examine the hysteresis of Q-SS relationships through continuous field measurements during flood events at inflow rivers of Yongdam Reservoir and Soyang Reservoir, and to analyze its effect on the bias of SS load estimation. The results confirmed that Q-SS relations display a high degree of scatter and clock-wise hysteresis during flood events, and higher SS concentrations were observed during rising limb than falling limb at the same discharge. The hysteresis caused significant bias and underestimation of SS loading to the reservoirs when the power function is used, which is important consideration in turbidity modeling for the reservoirs. As an alternative of Q-SS relation, turbidity-SS relation is suggested. The turbidity-SS relations showed less variations and dramatically reduced the bias with observed SS loading. Therefore, a real-time monitoring of inflow turbidity is necessary to better estimate of SS influx to the reservoirs and enhance the reliability of reservoir turbidity modeling.

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Observation and Simulation of Floodwater Intrusion and Sedimentation in the Shichikashuku Reservoir

Cited by 27 publications

References 29 publications

Effect of thermal stratification on interflow travel time in stratified reservoir

Effect of thermal stratification on interflow travel time in stratified reservoir

How are subaqueous sediment density flows triggered, what is their internal structure and how does it evolve? Direct observations from monitoring of active flows

Uncertainty of Discharge-SS Relationship Used for Turbid Flow Modeling

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