scholarly journals Research on the influence of diversion flow ratio on the water environment in Nanjing

2019 ◽  
Vol 19 (8) ◽  
pp. 2367-2378
Author(s):  
Weiwei Song ◽  
Yong Pang
Keyword(s):  
Water Level ◽  
Surface Runoff ◽  
Daily Precipitation ◽  
Water Environment ◽  
Flow Ratio ◽  
Frequency Curve ◽  
Level Difference ◽  
Pollutant Concentrations ◽  
Upstream Flow ◽  
Qinhuai River

Abstract In this paper, we take the Qinhuai River Basin in Nanjing as an example to study the influence of diversion flow ratio on the water environment. The daily precipitation of 20 rainfall stations in the basin was collected from 1962 to 2006, and the rainfall under different assurance rates was calculated by P-III frequency curve to calculate the surface runoff in different typical years. In the meantime, according to the downstream furcated estuary water level in different typical years, the diversion flow ratio under different frequencies was calculated by using a mathematical model of the water environment. The results show that the diversion flow ratio of a branch channel increases with the increase of water level difference, and the growth rate decreases gradually. The other branch channel diversion flow ratio decreases with the increase of water level difference, and the decreasing rate decreases gradually. The pollutant concentrations in the bifurcated rivers are equal, but the concentration decreases exponentially with the increase of the upstream flow. Under different rainfall frequencies, the diversion pollutant ratio and diversion flow ratio are equal in different months of different years.

scholarly journals Research on Water Environment Regulation of Artificial Playground Lake Interconnected Yangtze River

2018 ◽  
Vol 15 (10) ◽  
pp. 2110 ◽  
Author(s):  
Weiwei Song ◽  
Xingqian Fu ◽  
Yong Pang ◽  
Dahao Song ◽  
Qing Xu ◽  
...  
Keyword(s):  
Water Quality ◽  
Water Level ◽  
Yangtze River ◽  
Flood Control ◽  
Numerical Models ◽  
Rapid Development ◽  
Control Level ◽  
Water Environment ◽  
Water Diversion ◽  
Coupled Models

With the rapid development of China, water pollution is still a serious problem despite implementation of control measures. Reasonable water environment management measures are very important for improving water quality and controlling eutrophication. In this study, the coupled models of hydrodynamics, water quality, and eutrophication were used to predict artificial Playground Lake water quality in the Zhenjiang, China. Recommended “unilateral” and “bilateral” river numerical models were constructed to simulate the water quality in the Playground Lake without or with water diversion by pump, sluice and push pump. Under “unilateral” and “bilateral” river layouts, total nitrogen and total phosphorus meet the landscape water requirement through water diversion. Tourist season in spring and summer and its suitable temperature result in heavier eutrophication, while winter is lighter. Under pumping condition, water quality and eutrophication of “unilateral” river is better than “bilateral” rivers. Under sluice diversion, the central landscape lake of “unilateral river” is not smooth, and water quality and eutrophication is inferior to the “bilateral”. When the water level exceeds the flood control level (4.1 m), priority 1 is launched to discharge water from the Playground Lake. During operation of playground, when water level is less than the minimum level (3.3 m), priority 2 is turned on for pumping diversion or sluice diversion to Playground Lake. After opening the Yangtze river diversion channel sluice, priority 3 is launched for sluice diversion to the Playground Lake. When the temperature is less than 15 °C, from 15 °C to 25 °C and higher than 25 °C, the water quality can be maintained for 15 days, 10 days and 7 days, respectively. Corresponding to the conditions of different priority levels, reasonable choices of scheduling measures under different conditions to improve the water quality and control eutrophication of the Playground Lake. This article is relevant for the environmental management of the artificial Playground Lake, and similar lakes elsewhere.

scholarly journals Analysis of Flood Risk of Urban Agglomeration Polders Using Multivariate Copula

Water ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1470 ◽  
Author(s):  
Yuqin Gao ◽  
Dongdong Wang ◽  
Zhenxing Zhang ◽  
Zhenzhen Ma ◽  
Zichen Guo ◽  
...  
Keyword(s):  
Water Level ◽  
River Basin ◽  
Flood Risk ◽  
Eastern China ◽  
Urban Agglomeration ◽  
Dependence Structure ◽  
Flood Risks ◽  
The Impact ◽  
Flood Characteristics ◽  
Qinhuai River

Urban agglomeration polders (UAPs) are often used to control flooding in eastern China. The impacts of UAPs on individual flood events have been extensively examined, but how flood risks are influenced by UAPs is much less examined. This study aimed to explore a three-dimensional joint distribution of annual flood volume, peak flow and water level to examine UAPs’ impact on flood risks based on hydrological simulations. The dependence between pairwise hydrological characteristics are measured by rank correlation coefficients and graphs. An Archimedean Copula is applied to model the dependence structure. This approach is applied to the Qinhuai River Basin where UAPs are used proactively for flood control. The result shows that the Frank Copula can better represent the dependence structure in the Qinhuai River Basin. UAPs increase risks of individual flood characteristics and integrated risks. UAPs have a relatively greater impact on water level than the other two flood characteristics. It is noted that the impact on flood risk levels off for greater floods.

scholarly journals Effects of Water Intake Layout along the Wharf Shoreline on Ships

2019 ◽  
Vol 26 (4) ◽  
pp. 165-171
Author(s):  
Xian-wei Kong ◽  
Lei Ding ◽  
Hai-cheng Liu ◽  
Jing Qu ◽  
Xiao-song Li
Keyword(s):  
Numerical Model ◽  
Water Level ◽  
Physical Model ◽  
Water Intake ◽  
Hydrodynamic Forces ◽  
Lateral Flow ◽  
Real Situation ◽  
The Real ◽  
Level Difference ◽  
Two Sides

Abstract The construction of a water intake along the wharf shoreline can realise the intensive and comprehensive utilisation of the shoreline. However, since the water intake will increase the lateral flow at the wharf and also the hydrodynamic forces on ships, it will bring risks to ships mooring and leaving. The effects of the water intake on ships are studied using a physical model, numerical model and standard formulas. The results show that it leads to an increase of the hydrodynamic forces acting on the ship when the standard formulas are used to calculate the forces without considering the water level difference between the two sides of the ship. The results of the physical model are closer to the real situation. Measures that can effectively reduce the influence of the water intake on ships are proposed by increasing the distance between the wharf front and the front of the water intake as well as the depth of the water inlet windows.

scholarly journals Effect of Variations in Water Level and Wave Steepness on the Robustness of Wave Overtopping Estimation

2020 ◽  
Vol 8 (2) ◽  
pp. 63
Author(s):  
Nils B. Kerpen ◽  
Karl-Friedrich Daemrich ◽  
Oliver Lojek ◽  
Torsten Schlurmann
Keyword(s):  
Water Level ◽  
Wave Spectrum ◽  
Water Environment ◽  
Physical Modelling ◽  
Storm Surges ◽  
Water Levels ◽  
Coastal Protection ◽  
Wave Steepness ◽  
Wave Overtopping

The wave overtopping discharge at coastal defense structures is directly linked to the freeboard height. By means of physical modelling, experiments on wave overtopping volumes at sloped coastal structures are customarily determined for constant water levels and static wave steepness conditions (e.g., specific wave spectrum). These experiments are the basis for the formulation of empirically derived and widely acknowledged wave overtopping estimations for practical design purposes. By analysis and laboratory reproduction of typical features from exemplarily regarded real storm surge time series in German coastal waters, the role of non-stationary water level and wave steepness were analyzed and adjusted in experiments. The robustness of wave overtopping estimation formulae (i.e., the capabilities and limitations of such a static projection of dynamic boundary conditions) are outlined. Therefore, the classic static approach is contrasted with data stemming from tests in which both water level and wave steepness were dynamically altered in representative arrangements. The analysis reveals that mean overtopping discharges for simple sloping structures in an almost deep water environment could be robustly estimated for dynamic water level changes by means of the present design formulae. In contrast, the role of dynamic changes of the wave steepness led to a substantial discrepancy of overtopping volumes by a factor of two. This finding opens new discussion on methodology and criteria design of coastal protection infrastructure under dynamic exposure to storm surges and in lieu of alterations stemming from projected sea level rise.

Applying Water-Level Difference Control to Central Arizona Project

2011 ◽  
Vol 137 (12) ◽  
pp. 747-753 ◽  
Author(s):  
G. Guan ◽  
A. J. Clemmens ◽  
T. F. Kacerek ◽  
B. T. Wahlin
Keyword(s):  
Water Level ◽  
Central Arizona Project ◽  
Level Difference ◽  
Central Arizona

scholarly journals Design of edges in contour and half moons from edaphoclimatic parameters, for the endorrheic basin of lagunas de tajzara - ramsar site 1030

2021 ◽  
pp. 1-8
Author(s):  
Armando Schmidt-Gomez ◽  
Juan Manuel Olivares-Ramírez ◽  
Fermín Ferriol-Sánchez ◽  
Ángel Marroquín-De Jesús
Keyword(s):  
Green Infrastructure ◽  
Surface Runoff ◽  
Daily Rainfall ◽  
Separation Distance ◽  
Frequency Curve ◽  
Maximum Rainfall ◽  
Contour Lines ◽  
Intensity Duration Frequency ◽  
Moisture Conditions ◽  
Maximum Daily Rainfall

The collection of water is proposed from the design of contour borders and half moons, green infrastructure measures, to reduce surface runoff and increase the availability of water for vegetation. The contour and crescent ridges have land ridges with a trapezoidal section, which follow the contour lines, to compartmentalize the slope into smaller hydrological units, the ends of which are located on contour lines. With the data of maximum rainfall every 24 hours and parameters of Gumbel's Law modified, the equations of maximum daily rainfall height (hdT), rainfall height for a duration ´´t´´ (htT), and the Intensity Duration Frequency curve (ItT), for a duration of t <2h. Then considering the values of basic infiltration, vegetation cover, soil type and hydrological condition, the curve numbers were determined for different soil moisture conditions, later the separation length (L) between the Half Moons, and the borders was calculated. in contour, which were designed by means of 10 configurations between diameter and height, for the two infrastructures, being in Copacabana Valle, the greatest separation distance.

scholarly journals PENDANGKALAN ALUR PELAYARAN DI PELABUHAN PULAU BAAI BENGKULU

2016 ◽  
Vol 1 (3) ◽  
Author(s):  
Lukman Arifin ◽  
Juniar P. Hutagaol ◽  
Mustafa Hanafi
Keyword(s):  
Water Level ◽  
Current Velocity ◽  
Sea Water ◽  
Neap Tide ◽  
Spring Tide ◽  
Current Measurement ◽  
Geophysical Survey ◽  
Measurement Result ◽  
Level Difference ◽  
Sea Current

Alur pelayaran di Pelabuhan Pulau Baai Bengkulu selalu mengalami pendangkalan. Untuk mengetahui penyebab pendangkalan tersebut maka akan diberikan beberapa informasi hasil kajian geofisika kelautan dari beberapa metoda. Metoda tersebut terdiri dari pengukuran kedalaman laut, pengukuran arus dan pasang surut. Hasil pengukuran kedalaman laut memperlihatkan bahwa kedalaman yang paling dalam di bagian kolam pelabuhan adalah sekitar 12 meter dan yang terdalam di daerah alur juga 12 meter. Pengukuran arus laut memperlihatkan bahwa kecepatan arus pada saat pasang tertinggi lebih tinggi daripada kecepatan arus pada saat surut terendah. Pengendapan lebih besar terjadi pada saat air pasang, apalagi ditambah dengan adanya arus sepanjang pantai yang membawa sedimen ke arah alur. Tipe pasang surut laut di pelabuhan ini adalah tipe campuran ganda, artinya pasang dan surut akan terjadi sekali atau dua kali dalam sehari. Adapun perbedaan tinggi muka air pada saat air pasang dan saat air surut adalah 1,53 meter. Shoaling always occurs in the sailing channel of Pulau Baai Bengkulu Harbour. To know the reason of the shoaling, some information based on the result, of the analysis of several methods of marine geophysical survey are therefore presented. The methods are echo-sounding, sea current and tide measurement. Result of sounding shows that the deepest depth in the lagoon area is around 12 metres and the depth in the channel area is also 12 metres. Result of sea current measurement shows that current velocity during the spring tide is higher than the velocity during the neap tide. Sedimentation is higher in the spring tide, moreover it is increased by the existence of long shore current which transport the sediments into the channel. The type of the sea tide in the harbour is a mixed semi diurnal type which means that the spring and the neap will occur once or twice a day. The height of sea water level difference between spring tide and neap tide season is 1.53 metres.

scholarly journals THE NUMERICAL MODELLING OF THE EFFECT OF OCCURRENCE DURATION ON THE WATER LEVEL DIFFERENCE FOR THE BOSPHORUS STRAIT

2011 ◽  
Vol 1 (32) ◽  
pp. 28
Author(s):  
Mehmet Nuri Ozturk ◽  
Yalçın Yüksel
Keyword(s):  
Water Level ◽  
Black Sea ◽  
Surface Elevation ◽  
The Black Sea ◽  
Solution Technique ◽  
Initial Surface ◽  
Sea Of Marmara ◽  
Level Difference ◽  
First Case ◽  
Layered Flow

The straits connecting two large water bodies show highly strong and stratified currents related to meteorological, morphological and hydrodynamic conditions. The Bosphorus is a long sea strait connecting the Black Sea and the Sea of Marmara. There is a two layer current system in the Bosphorus, which is largely determined by conditions at the Black Sea. The upper layer flows from the Black Sea to the Sea of Marmara caused by decline in surface elevation between the Black Sea and Sea of Marmara. The lower layer flows in opposite direction caused by the density difference which is due to the difference in salinities. In this study the effect of occurrence duration of water level difference (Δh) on the Bosphorus current structure was modelled using a three dimensional hydrodynamic modelling approach. The approach is based on an unstructured flexible mesh and uses a finite volume solution technique, which provides an optimal flexibility while retaining an efficient numerical solution. The meshes are based on linear triangular elements. An uniform rectangular channel which has simple geometry compare with Bosphorus was used for modelling. The channel has Bosphorus average values in dimensions. It is 900 m in width, 32,000 m in length and 64 m in depth. The constant salinty bondary conditions were described at the open bondaries corresponding Marmara and Black Sea boundaries and no water level difference as initial surface elevation. Using k-ε turbulence choice and hydrostatic pressure assumption, the two different occurrence duration for the same increase at the water level difference were modelled. In the first case the increasing of the duration for the water level difference described shorter than the second case. The model results show that, in the first case one-layered flow becomes dominated whole the channel flow, on the other hand in the second case two-layered flow persisted.

scholarly journals Study on the Causes of the Decline of the Low Water Levels of Poyang Lake, China

2019 ◽  
Vol 117 ◽  
pp. 00014
Author(s):  
Jian-Zhao Guan ◽  
Lei Zhang ◽  
Chun-Ming Fang ◽  
Jun Feng
Keyword(s):  
Water Level ◽  
Poyang Lake ◽  
Dominant Role ◽  
Water Environment ◽  
River Channel ◽  
Water Levels ◽  
Sand Mining ◽  
Channel Erosion ◽  
Main River Channel ◽  
Water Level Decline

The drastic decline in the water level of Poyang Lake during the dry season has close connection with the water environment and lake ecology. The drastic decline has attracted considerable attention, and has led to intense scientific discussions regarding its cause. However, the importance of the different causes of the low water level decline has not been clearly illustrated. To improve the understanding of the reasons for the decline of low water levels in the Poyang Lake Waterway, this paper investigated the contributions of river channel erosion and sand mining to the water level decline. The results show that sand mining mainly occurred on the beaches of the Waterway, and had a relatively small effect on the change in the shape of the main river channel. It was found that the contribution of sand mining to the decline in the low water level was no more than 30%, while the average contribution by natural erosion was about 85%. This indicates that natural channel erosion of the Waterway has been significant, and plays a dominant role in the declining water levels of the Waterway.

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