scholarly journals A Comprehensive Investigation on Abnormal Impoundment of Reservoirs—A Case Study of Qionglin Reservoir in Kinmen Island

Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1463
Author(s):  
Yin-Chun Hung ◽  
Tung-Tsan Chen ◽  
Tsai-Fu Tsai ◽  
Hao-Xi Chen
Keyword(s):  
Catchment Area ◽  
Heavy Rain ◽  
Field Investigation ◽  
Tracer Test ◽  
Test Results ◽  
Reservoir Water ◽  
Reservoir Water Level ◽  
Resistivity Tomography ◽  
Reservoir Impoundment

Leakage is the most serious problem in reservoir operation, because heavy leakage influences reservoir impoundment efficiency and even leads to a complete loss of reservoir functions. Since its completion in 1982, Qionglin Reservoir has never been fully filled with water except in the spring of 1983 when there was heavy rain. The reservoir management unit suspected that its side slopes, bottom or dam might leak and carried out a number of leakage prevention and improvement works, but all of them failed to fulfill the impoundment function of the reservoir. Hence, this study attempts to find out the reasons why the reservoir cannot impound water. A series of tests and investigations are carried out in this study, including electrical resistivity tomography of dam, tracer test, geological drilling test, reservoir water level observation, investigation of reservoir catchment area and field investigation of dam. The test results and investigation results show that no leakage path and leakage are found. According to the analysis, there is no serious leakage of this reservoir. The main reason for the failure of impoundment is that massive improper development in the catchment area influences the runoff into the reservoir.

scholarly journals Stability Assessment of Landslides in Dahuaqiao Reservoir Area Based on Back Analysis of Slope Monitoring

2019 ◽  
Vol 2019 ◽  
pp. 1-15
Author(s):  
Yu-xiao Wang ◽  
Yu-jie Wang ◽  
Long Jiang ◽  
Ping Sun ◽  
Xingchao Lin ◽  
...  
Keyword(s):  
Back Analysis ◽  
In Situ Monitoring ◽  
Hydropower Project ◽  
Slope Failures ◽  
Reservoir Water ◽  
Reservoir Water Level ◽  
Reservoir Area ◽  
Reservoir Impoundment ◽  
Slope Instabilities

Dahuaqiao Hydropower Station is the sixth cascade hydropower project on the upper stream of the Lancang River, and a number of slope instabilities were found in the reservoir area before reservoir impoundment. The reservoir impoundment and fluctuation of the reservoir water level generally reactivate these potential slope failures or trigger new ones. Therefore, how to cope with the influence of these slope failures on dam safety has always been the focus of attention. However, it is unwise to stabilize all these potentially instable slopes by remedial measures. Based on a two-parameter and four-level back analysis method proposed in this paper, reasonable measures for landslide management are suggested on the basis of the in situ monitoring results and back analysis of geomaterial strength parameters.

scholarly journals The Impact of Reservoir Fluctuations on Reactivated Large Landslides: A Case Study

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Javed Iqbal ◽  
Xinbin Tu ◽  
Wei Gao
Keyword(s):  
Slip Surface ◽  
Strength Reduction ◽  
Slope Instability ◽  
Water Level Fluctuations ◽  
Silty Mudstone ◽  
Jinsha River ◽  
Reservoir Water ◽  
Reservoir Water Level ◽  
The Impact

Filling of Xiangjiaba Reservoir Lake in the Southwest China triggered and reactivated numerous landslides due to water fluctuation. In order to understand the relationship between reservoirs and slope instability, a typical reservoir landslide (Dasha landslide) at the right bank of Jinsha River was selected as a case study for in-depth investigations. The detailed field investigations were carried out to identify the landslide with respect to its surroundings and to find out the slip surface. Boreholes were drilled to find out the subsurface lithology and the depth of failure of Dasha landslide. The in situ geotechnical tests were performed, and the soil samples from exposed slip surface were retrieved for geotechnical laboratory analysis. Finally, stability analysis was done using the 3D strength reduction method under different conditions of reservoir water level fluctuations and rainfall conditions. The in-depth investigations show that the Dasha landslide is a bedding rockslide which was once activated in 1986. The topography of Dasha landslide is relatively flat, while the back scarp and local terrain is relatively steep. The total volume of landslides is about 580×104 m3 with an average thickness of 20 m. Bedrock in the landslide area is composed of Suining Formation of the Jurassic age. The main rock type is silty mudstone with sandstone, and the bedding orientation is 300~310° ∠ 7~22°. The factor of safety (FOS) of Dasha landslide obtained by 3D strength reduction cannot meet the minimum safety requirement under the working condition of reservoir level fluctuation as designed, with effect of rainfall and rapid drawdown.

scholarly journals FORECASTING THE FLOOD STAGE OF A RESERVOIR BASED ON THE CHANGES IN UPSTREAM RAINFALL PATTERN

2019 ◽  
Vol 14 (Number 2) ◽  
pp. 46-52
Author(s):  
Raja Nurul Mardhiah Raja Mohamad ◽  
Wan Hussain Wan Ishak
Keyword(s):  
Water Storage ◽  
Heavy Rain ◽  
Rainfall Pattern ◽  
Forecasting Model ◽  
Water Usage ◽  
Water Release ◽  
Reservoir Water ◽  
Reservoir Water Level ◽  
Early Decision ◽  
Excessive Water

Flood is amongthe major disasters in Malaysia. Flood occurs whenthe existing waterways areunable to support large amountsof waterduring heavy rain seasons. Reservoirshavebeen used as one of the flood mitigation approachesin the country. A reservoir can hold excessive water to ensure water flow tothedownstream area is under the safe capacity of the waterway. However, due to the needs of the society, a reservoir also serves other purposes such as water supply and recreation. Therefore, reservoir water storage should be maintained to satisfy water usage,and at the same time,the water needsto be released to reserve space forincoming water. This conflict causesproblemsto reservoir operatorswhen making the water release decision. In this paper, a forecasting model wasproposed to forecast the flood stage of a reservoir based on the upstream rainfall pattern. This model couldbe used by reservoir operatorsin the early decision-makingstageofreleasingwater before the reservoir reaches its maximum capacity. Simultaneously,the reservoir water level could be maintainedfor other uses. In this study, the experiments conducted provedthat an Artificial Neural Network is capable ofproducingan acceptable performance in terms of its accuracy.

scholarly journals The Value of Hydrologic Information in Reservoir Outflow Decision-Making

Water ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1372 ◽  
Author(s):  
Kebing Chen ◽  
Shenglian Guo ◽  
Shaokun He ◽  
Tao Xu ◽  
Yixuan Zhong ◽  
...  
Keyword(s):  
Decision Making ◽  
Simulation Models ◽  
Reservoir Water ◽  
Reservoir Water Level ◽  
Flood Season ◽  
Proposed Model ◽  
Importance Ranking ◽  
Input Variables ◽  
The One

The controlled outflows from a reservoir are highly dependent on the decisions made by the reservoir operators who mainly rely on available hydrologic information, such as past outflows, reservoir water level and forecasted inflows. In this study, Random Forests (RF) algorithm is used to build reservoir outflow simulation model to evaluate the value of hydrologic information. The Three Gorges Reservoir (TGR) in China is selected as a case study. As input variables of the model, the classic hydrologic information is divided into past, current and future information. Several different simulation models are established based on the combinations of these three groups of information. The influences and value of hydrologic information on reservoir outflow decision-making are evaluated from two different perspectives, the one is the simulation result of different models and the other is the importance ranking of the input variables in RF algorithm. Simulation results demonstrate that the proposed model is able to reasonably simulate outflow decisions of TGR. It is shown that past outflow is the most important information and the forecasted inflows are more important in the flood season than in the non-flood season for reservoir operation decision-making.

scholarly journals A Simplified Solution for Calculating the Phreatic Line and Slope Stability during a Sudden Drawdown of the Reservoir Water Level

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Guanhua Sun ◽  
Shan Lin ◽  
Wei Jiang ◽  
Yongtao Yang
Keyword(s):  
Slope Stability ◽  
Water Level ◽  
Slip Surface ◽  
Laplacian Matrix ◽  
Safety Factors ◽  
Reservoir Water ◽  
Reservoir Water Level ◽  
The Three Gorges ◽  
Simplified Solution

On the basis of the Boussinesq unsteady seepage differential equation, a new simplified formula for the phreatic line of slopes under the condition of decreasing reservoir water level is derived by means of the Laplacian matrix and its inverse transform. In this context, the expression of normal stress on the slip surface under seepage forces is deduced, and a procedure for obtaining the safety factors under hydrodynamic forces is proposed. A case study of the Three Gorges Reservoir is used to analyze the influences of the water level, decreasing velocity and the permeability coefficient on slope stability.

scholarly journals Analysis of the impact of Shifosi Reservoir water level on underground water

2018 ◽  
Vol 9 (2) ◽  
pp. 367-382 ◽  
Author(s):  
B. Yan ◽  
Y. Xie ◽  
C. J. Guo ◽  
C. S. Zhao
Keyword(s):  
Water Level ◽  
Groundwater Level ◽  
Underground Water ◽  
Drainage Ditches ◽  
Visual Modflow ◽  
Reservoir Water ◽  
Reservoir Water Level ◽  
Reservoir Impoundment ◽  
The Right ◽  
The Impact

Abstract Shifosi Reservoir is a plain reservoir. High groundwater level in the nearby area caused by impoundment of the reservoir has not only submerged the nearby farmland and village, but also reduced production and affected farmers' living. To analyze the influence of reservoir impoundment on surrounding groundwater level, Visual MODFLOW software was used to simulate the groundwater in Zhujiapu and Chenpingpu areas on the right auxiliary dam of Shifosi Reservoir. Results show that with the rise of the reservoir water level from 45.5 m to 46.2 m and 46.5 m, the area under the critical groundwater table (45 m) in the study area decreased in turn. In 2008, when the reservoir water level was 46.2 m and 46.5 m, the area under the critical groundwater level was reduced by 0.64 km2 and 0.84 km2, respectively, compared with the case of reservoir water level of 45.5 m, and would decrease by 0.38 km2 and 0.45 km2, respectively, by 2022. This indicates that the impact of reservoir impoundment on groundwater level is great. Therefore, relief wells or drainage ditches should be arranged along the auxiliary dam axis to effectively lower the groundwater level, and improve the surrounding ecological environment of the reservoir.

scholarly journals Study on the Deformation Mechanism of Reservoir Landslides Considering Rheological Properties of the Slip Zone Soil: A Case Study in the Three Gorges Reservoir Region

2020 ◽  
Vol 12 (16) ◽  
pp. 6427
Author(s):  
Chun Li ◽  
Huiming Tang ◽  
Yankun Wang
Keyword(s):  
Water Level ◽  
Three Gorges Reservoir ◽  
Water Level Fluctuation ◽  
Level Fluctuation ◽  
Three Gorges ◽  
Reservoir Water ◽  
Reservoir Water Level ◽  
The Three Gorges ◽  
Reservoir Water Level Fluctuation

Reservoir water level fluctuation is one of the main extrinsic factors that could change the stress field in landslides, as well as the mechanical strength of geomaterials, hence affecting the deformation and stability of landslides. The largest reservoir landslide in the Three Gorges Reservoir area was selected for a case study. The impact of reservoir water level fluctuation is represented by the dynamic change in the underground seepage field and was thereby analyzed with numerical modeling. The deformation behavior considering the rheological properties of the slip zone soil was studied. The sudden change in the displacement–time curve was selected as the failure criterion for the investigated landslide. The evolution process of the accelerated deformation stage was divided into slow acceleration, fast acceleration, and rapid acceleration stages. The Huangtupo landslide is characterized by a retrogressive landslide and is currently in the creep deformation stage; the deformation mechanism and deformation characteristics are closely related to the reservoir water level fluctuation. Research was carried out by means of field investigation, in situ monitoring, and numerical simulation to provide a true and reliable result for stability evaluation.

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