scholarly journals Modelling the Impacts of Bathymetric Changes on Water Level in China’s Largest Freshwater Lake

Water ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1469 ◽  
Author(s):  
Lingyan Qi ◽  
Jiacong Huang ◽  
Junfeng Gao ◽  
Zhen Cui
Keyword(s):  
Water Level ◽  
Water Resource Management ◽  
Freshwater Lake ◽  
Lake Ecosystem ◽  
Spatial Gradient ◽  
Dramatic Decline ◽  
Hydrodynamic Processes ◽  
Lake Poyang ◽  
The Stability ◽  
Bathymetric Changes

A recent dramatic decline in water level during the dry season in China’s largest freshwater lake (Lake Poyang) significantly influenced water availability and biogeochemical processes. To learn the potential causes of water level decline, this study investigated the hydrodynamic response to bathymetric changes during three typical hydrological years by scenario simulation using Environmental Fluid Dynamics Code (EFDC). The simulation results indicated that bathymetric changes resulted in a water level decrease during a low water level period. Inter-annual variation in the decrease rate implied that water level in typical dry and wet years were influenced more significantly than that in moderate hydrological years. A spatial gradient in the distribution of water level changes was also observed, which was mainly concentrated in the main channel. Water velocities also slowed down, weakly corresponding to the decrease in water level during the low water level period. Overall, bathymetric changes caused by sand mining contributed to water level and velocity variations, influencing the stability and sustainability of the lake ecosystem. This study can potentially enhance our understanding of the hydrodynamic processes in Lake Poyang and support water resource management.

scholarly journals Simplified Lake Surface Area Method for the Minimum Ecological Water Level of Lakes and Wetlands

Water ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 1056 ◽  
Author(s):  
Songpu Shang ◽  
Songhao Shang
Keyword(s):  
Water Level ◽  
Surface Area ◽  
Lake Level ◽  
Lake Ecosystem ◽  
Lake Surface ◽  
Area Method ◽  
Ecosystem Protection ◽  
Lake Morphology ◽  
Lake Surface Area ◽  
Ecological Water Level

The determination of the rational minimum ecological water level is the base for the protection of ecosystems in shrinking lakes and wetlands. Based on the lake surface area method, a simplified lake surface area method was proposed to define the minimum ecological lake level from the lake level-logarithm of the surface area curve. The curve slope at the minimum ecological lake level is the ratio of the maximum lake storage to the maximum surface area. For most practical cases when the curve cannot be expressed as a simple analytical function, the minimum ecological lake level can be determined numerically using the weighted sum method for an equivalent multi-objective optimization model that balances ecosystem protection and water use. This method requires fewer data of lake morphology and is simple to compute. Therefore, it is more convenient to use this method in the assessment of the ecological lake level. The proposed method was used to determine the minimum ecological water level for one freshwater lake, one saltwater lake, and one wetland in China. The results can be used in the lake ecosystem protection planning and the rational use of water resources in the lake or wetland basins.

Decadal Sedimentation in China's Largest Freshwater Lake, Poyang Lake

2018 ◽  
Vol 19 (8) ◽  
pp. 2384-2396
Author(s):  
Xuefei Mei ◽  
Juan Du ◽  
Zhijun Dai ◽  
Jinzhou Du ◽  
Jinjuan Gao ◽  
...  
Keyword(s):  
Poyang Lake ◽  
Freshwater Lake ◽  
Lake Poyang

Investigation Into The Stability Of Hydrodynamic Processes In The Depth Centrifugal Pump And Pipeline System

2013 ◽  
Author(s):  
Marijonas Bogdevčius ◽  
Jolanta Janutėnienė ◽  
Rimantas Didžiokas ◽  
Vadim Nikitin ◽  
Saulius Razmas ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Pipeline System ◽  
Hydrodynamic Processes ◽  
The Stability

scholarly journals Unsteady Seepage Behavior of an Earthfill Dam During Drought-Flood Cycles

Geosciences ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 17 ◽  
Author(s):  
Ziyang Li ◽  
Wei Ye ◽  
Miroslav Marence ◽  
Jeremy Bricker
Keyword(s):  
Pressure Gradient ◽  
Water Level ◽  
Pore Pressure ◽  
Internal Erosion ◽  
Reservoir Water ◽  
Reservoir Water Level ◽  
Upstream Slope ◽  
Earthfill Dams ◽  
The Stability ◽  
Pore Pressure Gradient

Climate change with extreme hydrological conditions, such as drought and flood, bring new challenges to seepage behavior and the stability of earthfill dams. Taking a drought-stricken earthfill dam of China as an example, the influence of drought-flood cycles on dam seepage behavior is analyzed. This paper includes a clay sample laboratory experiment and an unsteady finite element method seepage simulation of the mentioned dam. Results show that severe drought causes cracks on the surface of the clay soil sample. Long-term drought causes deeper cracks and induces a sharp increase of suction pressure, indicating that the cracks would become channels for rain infiltration into the dam during subsequent rainfall, increasing the potential for internal erosion and decreasing dam stability. Measures to prevent infiltration on the dam slope surface are investigated, for the prevention of deep crack formation during long lasting droughts. Unsteady seepage indicators including instantaneous phreatic lines, equipotential lines and pore pressure gradient in the dam, are calculated and analyzed under two assumed conditions with different reservoir water level fluctuations. Results show that when the water level changes rapidly, the phreatic line is curved and constantly changing. As water level rises, equipotential lines shift upstream, and the pore pressure gradient in the dam’s main body is larger than that of steady seepage. Furthermore, the faster the water level rises, the larger the pore pressure gradient is. This may cause internal erosion. Furthermore, the case of a cracked upstream slope is modelled via an equivalent permeability coefficient, which shows that the pore pressure gradient in the zone beneath the cracks increases by 5.9% at the maximum water level; this could exacerbate internal erosion. In addition, results are in agreement with prior literature that rapid drawdown of the reservoir water level is detrimental to the stability of the upstream slope based on embankment slope stability as calculated by the Simplified Bishop Method. It is concluded that fluctuations of reservoir water level should be strictly controlled during drought-flood cycles; both the drawdown rate and the fill rate must be regulated to avoid the internal erosion of earthfill dams.

Waters Ecological Reconstruction of Ling Lake Scenic Area in Anqing

2012 ◽  
Vol 253-255 ◽  
pp. 809-816
Author(s):  
Li Hua Zhang ◽  
Bao Hua Zhou
Keyword(s):  
Surface Coverage ◽  
Nature Reserve ◽  
Water Remediation ◽  
Ecological Environment ◽  
Lake Ecosystem ◽  
Main Body ◽  
Landscape Water ◽  
The Stability ◽  
Landscape Ecological ◽  
Ecological Reconstruction

In recent years, the landscape water of Anqing Ling Lake scenic area became severe eutrophication, resulting in the destruction of the ecological balance. The eigenvalues of nature reserve in the wetland along the Yangtze River in Anqing such as the species diversity of Lake Ecosystem, plant community structure and the stability of the ecological environment were simulated in this paper. We proposed the target and principles for the water remediation and landscape ecological reconstruction of Ling Lake scenic area, determined that Trapa Comm, Nelumb Comm, Zizania Comm, Vallisneria Comm and Phragmites Comm should treated as the main body of the ecological reconstruction, discussed the population structure, water surface coverage, ecological and landscape function for each community. Furthermore, we also discussed the request controlling density for phytoplankton and the proportion for the fish fingerlings, as well as the measures for the optimization on ecological reconstruction.

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