scholarly journals Characteristics and Practices of Ecological Flow in Rivers with Flow Reductions Due to Water Storage and Hydropower Projects in China

Water ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 1091 ◽  
Author(s):  
Lejun Ma ◽  
Xingnan Zhang ◽  
Huan Wang ◽  
Changjun Qi
Keyword(s):  
Calculation Method ◽  
River Flow ◽  
Water Storage ◽  
Engineering Calculation ◽  
Water Diversion ◽  
Western China ◽  
Flow Management ◽  
Riverine Ecosystems ◽  
Management Scheme ◽  
Ecological Flow

Water and flow reductions in the channels downstream of water storage and hydropower projects have significant impacts on aquatic ecosystems. Understanding and analyzing the ecosystem status is of great significance to facilitate the protection of riverine ecosystems. A database was established based on the 2000–2017 environmental impact assessment (EIA) reports on water storage and hydropower projects in China, and corresponding analysis software was built based on an ArcGIS spatial analysis platform. The projects in China are mainly found in the Yangtze and Pearl River basins and in south-western China. The hydropower projects have a larger influence than the water storage projects on the flow of downstream rivers sections, and most of the hydropower projects, especially the water diversion projects, cause flow reductions in the downstream rivers. An ecological flow management mechanism in China implemented in 2006 provided a promising method to alleviate river flow reductions. However, there is still only one kind of ecological flow calculation method and few ecological flow regulation measures in use. Based on the advantages and problems of the existing ecological flow management system, this paper proposes a management scheme based on a regional-engineering calculation method. The results can facilitate decision making in ecological flow management.

An Engineering Calculation Method for Multi-Component Stagnant Droplet Evaporation With Finite Diffusivity

1994 ◽  
Author(s):  
J. S. Chin
Keyword(s):  
Heat Transfer ◽  
Diffusion Coefficient ◽  
Liquid Phase ◽  
Vapor Pressure ◽  
Molecular Mass ◽  
Calculation Method ◽  
Engineering Calculation ◽  
Droplet Evaporation ◽  
Diffusion Resistance ◽  
Distillation Curve

A practical engineering calculation method has been formulated for commercial multicomponent fuel stagnant droplet evaporation with variable finite mass and thermal diffusivity. Instead of solving the transient liquid phase mass and heat transfer partial differential equation set, a totally different approach is used. With zero or infinite mass diffusion resistance in liquid phase, it is possible to obtain vapor pressure and vapor molecular mass based on the distillation curve of these turbine fuels. It is determined that Peclet number (Pef) is a suitable parameter to represent the mass diffusion resistance in liquid phase. The vapor pressure and vapor molecular mass at constant finite Pef is expressed as a function of finite Pef, vapor pressure, and molecular mass at zero Pef and infinite Pef. At any time step, with variable finite Pef, the above equation is still valid, and PFsPef=∞, PFsPef=0, MfvPef=∞, MfvPef=0 are calculated from PFsPef≡∞, PFsPef≡0, MfvPef≡∞, MfvPef≡0, thus PFs and Mfv can be determined in a global way which eventually is based on the distillation curve of fuel. The explicit solution of transient heat transfer equation is used to have droplet surface temperature and droplet average temperature as a function of surface Nusselt number and non-dimensional time. The effect of varying com position of multi-component fuel evaporation is taken into account by expressing the properties as a function of molecular mass, acentric factor, critical temperature, and critical pressure. A specific calculation method is developed for liquid fuel diffusion coefficient, also special care is taken to calculate the binary diffusion coefficient of fuel vapor-air in gaseous phase. The effect of Stefan flow and natural convection has been included. The predictions from the present evaporation model for different turbine fuels under very wide temperature ranges have been compared with experimental data with good agreement.

Based on Estimation of the Ionospheric Characteristics HF Frequency Prediction Method

2012 ◽  
Vol 190-191 ◽  
pp. 936-939
Author(s):  
Chao Li ◽  
Yun Jiang Liu ◽  
Heng Yang Zhang ◽  
Xiao Peng Yang ◽  
Feng Wang
Keyword(s):  
Calculation Method ◽  
Prediction Method ◽  
Engineering Calculation ◽  
International Telecommunication Union ◽  
International Telecommunication ◽  
Time Availability ◽  
Hf Channel

To grasp Complex characteristics of shortwave (HF) channel is the key and difficulty to research HF communication. On the premise of comprehending the ionosphere prediction method in the Asia Oceania region, HF frequency prediction method recommended by the International Telecommunication Union (ITU) is improved in this paper, and the engineering calculation method of predicting HF frequency in the Asia Oceania region is concluded and summarized. Comparing with the ITS (the Institute for Telecommunication Science) software’s predicting result, the method is improved to some extent in time availability and SNR in the receiving point.

scholarly journals Impact of sulfamethoxazole on a riverine microbiome

2021 ◽  
Author(s):  
Chiara Borsetto ◽  
Sebastien Raguideau ◽  
Emma R Travis ◽  
Dae-Wi Kim ◽  
Do-Hoon Lee ◽  
...  
Keyword(s):  
River Flow ◽  
Wastewater Treatment Plants ◽  
Antibiotic Resistance Genes ◽  
Resistant Bacteria ◽  
Water Fraction ◽  
Riverine Ecosystems ◽  
Short Term Exposure ◽  
Bacterial Microbiome ◽  
The Impact

The continued emergence of bacterial pathogens presenting antimicrobial resistance is widely recognised as a global health threat and recent attention focused on potential environmental reservoirs of antibiotic resistance genes (ARGs). Freshwater environments such as rivers represent a potential hotspot for ARGs and antibiotic resistant bacteria as they are receiving systems for effluent discharges from wastewater treatment plants (WWTPs). Effluent also contains low levels of different antimicrobials including antibiotics and biocides. Sulfonamides are antibacterial chemicals widely used in clinical, veterinary and agricultural settings and are frequently detected in sewage sludge and manure in addition to riverine ecosystems. The impact of such exposure on ARG prevalence and diversity is unknown, so the aim of this study was to investigate the release of a sub-lethal concentration of the sulfonamide compound sulfamethoxazole (SMX) on the river bacterial microbiome using a flume system. This system was a semi-natural in vitro flume using river water (30 L) and sediment with circulation to mimic river flow. A combination of 'omics' approaches were conducted to study the impact of SMX exposure on the microbiomes within the flumes. Metagenomic analysis showed that the addition of low concentrations of SMX (<4 μg L-1) had a limited effect on the bacterial resistome in the water fraction only, with no impact observed in the sediment. Metaproteomics did not show differences in ARGs expression with SMX exposure in water. Overall, the river bacterial community was resilient to short term exposure to sub-lethal concentrations of SMX which mimics the exposure such communities experience downstream of WWTPs throughout the year.

scholarly journals Detecting Water Diversion Fingerprints in the Danjiangkou Reservoir from Satellite Gravimetry and Altimetry Data

Sensors ◽  
2019 ◽  
Vol 19 (16) ◽  
pp. 3510
Author(s):  
Nengfang Chao ◽  
Gang Chen ◽  
Zhicai Luo ◽  
Xiaoli Su ◽  
Zhengtao Wang ◽  
...  
Keyword(s):  
Water Level ◽  
Water Storage ◽  
Water Diversion ◽  
Spatiotemporal Variability ◽  
Spatiotemporal Pattern ◽  
The South ◽  
Danjiangkou Reservoir ◽  
Water Diversion Project ◽  
North Water ◽  
And Storage

The Danjiangkou Reservoir (DJKR) is the freshwater source for the Middle Route of the South-to-North Water Diversion Project in China, and its water level and storage changes are important for water resource management. To maximize the potential capacity of the Gravity Recovery and Climate Experiment (GRACE) mission, an improved Lagrange multiplier method (ILMM) is first proposed to detect terrestrial water storage anomalies (TWSA) in the small-scale basin (DJKR). Moreover, for the first time, water diversion fingerprints are proposed to analyze the spatiotemporal pattern of the TWSA in the DJKR. The results indicate that the increased water level and storage signals due to the DJKR impoundment in 2014 can be effectively detected by using the ILMM, and they agree well with the results from altimetry and in situ data. Additionally, the water diversion fingerprints due to the DJKR impoundment are inferred, and describe the progression of spatiotemporal variability in water storage. The results show that water storage decreased in the upper Hanjiang River and increased in the DJKR as well as to the east of it during the period 2013–2015. Our research provides a scientific decision-making basis for monitoring the water resources of the DJKR and managing the South-to-North Water Diversion Project.

An Engineering Correction Method for Buckling Load of Dense Stiffened Panels

2020 ◽  
Vol 1003 ◽  
pp. 92-97
Author(s):  
Wen Hao Liu ◽  
Rui Xiang Bai ◽  
Kang Su ◽  
Jian Chao Zou ◽  
Da Liu ◽  
...  
Keyword(s):  
Finite Element ◽  
Calculation Method ◽  
Engineering Calculation ◽  
Correction Method ◽  
Buckling Loads ◽  
Buckling Modes ◽  
Stiffened Panels ◽  
Element Simulation ◽  
Compressive Buckling ◽  
The Stability

It is convenient for designers to get the buckling loads of sparse stiffened panels quickly by using engineering calculation method to analyze the stability of composite stiffened panels, but it is still unable to meet the accuracy requirements of analysis of dense stiffened panels. The buckling loads of stiffened panels are closely related to the buckling modes. Based on capturing and analyzing the Compressive Buckling waveforms of T-shaped densely stiffened panels, this paper presents a formula for calculating the buckling loads according to the geometric coefficients. The results are very similar to those of finite element simulation, and can be used to calculate the buckling loads of sparse and dense stiffened panels with different stiffeners.

scholarly journals Evaluation and improvement of remote sensing-based methods for river flow management

2020 ◽  
Vol 117 ◽  
pp. 102839 ◽  
Author(s):  
H.T. Samboko ◽  
I. Abas ◽  
W.M.J. Luxemburg ◽  
H.H.G. Savenije ◽  
H. Makurira ◽  
...  
Keyword(s):  
Remote Sensing ◽  
River Flow ◽  
Flow Management
Sign in / Sign up

Export Citation Format

Share Document