scholarly journals Towards a Better Air Assisted Flare Design for Low Flow Conditions: Analysis of Radial Slot and Flow Effects

2021 ◽  
Author(s):  
Hayder A. Alhameedi ◽  
Aso A. Hassan ◽  
Joseph D. Smith
Keyword(s):  
Low Flow ◽  
Flow Conditions ◽  
Radial Slot ◽  
Flow Effects

Geochemistry of Red Mountain Creek, Colorado, under low-flow conditions, August 2002

2005 ◽  
Author(s):  
Robert L. Runkel ◽  
Briant A. Kimball ◽  
Katherine Walton-Day ◽  
Philip L. Verplanck
Keyword(s):  
Low Flow ◽  
Flow Conditions

Sources of Chlorophenolic Compounds to the Fraser River Estuary

1988 ◽  
Vol 23 (1) ◽  
pp. 55-68 ◽  
Author(s):  
J. H. Carey ◽  
J. H. Hart
Keyword(s):  
River Flow ◽  
River Estuary ◽  
Low Flow ◽  
Fraser River ◽  
Pulp Mills ◽  
Flow Conditions ◽  
Downstream Site ◽  
Upstream Site ◽  
The North ◽  
Main River

Abstract The identity and concentrations of chlorophenolic compounds in the Fraser River estuary were determined under conditions of high and low river flow at three sites: a site upstream from the trifurcation and at downstream sites for each main river arm. Major chlorophenolics present under both flow regimes were 2,4,6-trichlorophenol (2,4,6-TCP), 2,3,4,6-tetrachlorophenol (2,3,4,6-TeCP), pentachlorophenol (PCP), tetrachloroguaiacol (TeCG) and a compound tentatively identified as 3,4,5-trichloroguaiacol (3,4,5-TCG). Under high flow conditions, concentrations of the guaiacols were higher than any of the Chlorophenols and concentrations of all five chlorophenolics appeared to correlate. Under low flow conditions, concentrations of chloroguaiacols were higher than Chlorophenols at the upstream site and at the downstream site on the Main Arm, whereas at the downstream site on the North Arm, concentrations of 2,3,4,6-TeCP and PCP were higher than the chloroguaiacols in some samples. Overall, the results indicate that pulp mills upstream from the estuary are important sources of chlorophenolics to the estuary under all flow conditions. Additional episodic inputs of 2,3,4,6-TeCP and PCP from lumber mills occur along the North Arm. When these inputs occur, they can cause the concentrations of Chlorophenols in the North Arm to exceed provisional objectives. If chloroguaiacols are included as part of the objective, concentrations of total chlorophenolics in water entering the estuary can approach and exceed these objectives, especially under low flow conditions.

scholarly journals Forensic Investigation of Four Monitored Green Infrastructure Inlets

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1787
Author(s):  
Leena J. Shevade ◽  
Franco A. Montalto
Keyword(s):  
Measurement Uncertainty ◽  
Green Infrastructure ◽  
Stormwater Management ◽  
Catchment Area ◽  
Low Flow ◽  
Inflow Rate ◽  
Forensic Investigation ◽  
Flow Conditions ◽  
The Mean

Green infrastructure (GI) is viewed as a sustainable approach to stormwater management that is being rapidly implemented, outpacing the ability of researchers to compare the effectiveness of alternate design configurations. This paper investigated inflow data collected at four GI inlets. The performance of these four GI inlets, all of which were engineered with the same inlet lengths and shapes, was evaluated through field monitoring. A forensic interpretation of the observed inlet performance was conducted using conclusions regarding the role of inlet clogging and inflow rate as described in the previously published work. The mean inlet efficiency (meanPE), which represents the percentage of tributary area runoff that enters the inlet was 65% for the Nashville inlet, while at Happyland the NW inlet averaged 30%, the SW inlet 25%, and the SE inlet 10%, considering all recorded events during the monitoring periods. The analysis suggests that inlet clogging was the main reason for lower inlet efficiency at the SW and NW inlets, while for the SE inlet, performance was compromised by a reverse cross slope of the street. Spatial variability of rainfall, measurement uncertainty, uncertain tributary catchment area, and inlet depression characteristics are also correlated with inlet PE. The research suggests that placement of monitoring sensors should consider low flow conditions and a strategy to measure them. Additional research on the role of various maintenance protocols in inlet hydraulics is recommended.

Influence of climate change on low flow conditions. Case study: Laborec River, eastern Slovakia

2021 ◽  
Author(s):  
Katarzyna Kubiak-Wójcicka ◽  
Martina Zeleňáková ◽  
Peter Blištan ◽  
Dorota Simonová ◽  
Agnieszka Pilarska
Keyword(s):  
Climate Change ◽  
Low Flow ◽  
Flow Conditions

scholarly journals Soil microbial inoculation during flood events shapes headwater stream microbial communities and diversity

2021 ◽  
Author(s):  
Florian Caillon ◽  
Katharina Besemer ◽  
Peter Peduzzi ◽  
Jakob Schelker
Keyword(s):  
Microbial Diversity ◽  
Bacterial Diversity ◽  
Soil Water ◽  
Headwater Streams ◽  
High Flow ◽  
Low Flow ◽  
Flood Events ◽  
Flow Conditions ◽  
Soil Microbial ◽  
Microbial Inoculation

AbstractFlood events are now recognized as potentially important occasions for the transfer of soil microbes to stream ecosystems. Yet, little is known about these “dynamic pulses of microbial life” for stream bacterial community composition (BCC) and diversity. In this study, we explored the potential alteration of stream BCC by soil inoculation during high flow events in six pre-alpine first order streams and the larger Oberer Seebach. During 1 year, we compared variations of BCC in soil water, stream water and in benthic biofilms at different flow conditions (low to intermediate flows versus high flow). Bacterial diversity was lowest in biofilms, followed by soils and highest in headwater streams and the Oberer Seebach. In headwater streams, bacterial diversity was significantly higher during high flow, as compared to low flow (Shannon diversity: 7.6 versus 7.9 at low versus high flow, respectively, p < 0.001). Approximately 70% of the bacterial operational taxonomic units (OTUs) from streams and stream biofilms were the same as in soil water, while in the latter one third of the OTUs were specific to high flow conditions. These soil high-flow OTUs were also found in streams and biofilms at other times of the year. These results demonstrate the relevance of floods in generating short and reoccurring inoculation events for flowing waters. Moreover, they show that soil microbial inoculation during high flow enhances microbial diversity and shapes fluvial BCC even during low flow. Hence, soil microbial inoculation during floods could act as a previously overlooked driver of microbial diversity in headwater streams.

scholarly journals Numerical hydrodynamic researches for justifying design of the Nizhny Novgorod low-head hydraulic system

2019 ◽  
pp. 3-3
Author(s):  
Anna Glotko ◽  
Vitalii Belikov ◽  
Natalia Borisova ◽  
Ekaterina Vasil`eva ◽  
Aleksey Rumjancev
Keyword(s):  
Numerical Methods ◽  
Hydraulic System ◽  
Problem Area ◽  
Low Flow ◽  
Hydroelectric Power Station ◽  
Two Dimensional ◽  
Hydroelectric Power ◽  
Flow Conditions ◽  
Power Station ◽  
Low Head

Introduction. A problem area of the Volga river between the Nizhny Novgorod hydroelectric power station and the city of Nizhny Novgorod has been surveyed, where unfavourable conditions for navigation, power generation, and safe living in the downstream are formed as a result of the landing level. The only solution to the problem is construction of a low-head hydraulic system (NNGU) that will reduce intensity of relief re-formations in the downstream of the Nizhny Novgorod hydraulic system and stop lowering of the bottom and level marks in this area. Purpose of this research is to study processes that occur upstream and downstream from the site of the facility to identify hazardous trends and develop practical solutions to minimize negative impacts; as well as a review of mathematical models conducted in this area for improving navigation conditions. Materials and methods. Materials of previous researches on this subject, pre-design engineering surveys and layout drawings of the designed hydraulic system are used. The researches have been performed with numerical methods using Stream 2D software package that is based on the two-dimensional differential equation Saint-Venant system. Options for low-flow conditions are considered, taking into account passing of the Nizhny Novgorod hydroelectric power station, as well as rare floods. Results. Plans for distribution of velocity modules and vectors are created, which show that construction of the low-pressure hydraulic system results in decrease in slopes and velocities of water in the problem area of the Volga-Kama cascade, as a result of which intensity of bottom deformations decreases. Rare flow passage demonstrated that difference in pools is insignificant, while, at the same time, flow of water along the left-bank floodplain passes more than believed before. Calculations of low-flow conditions demonstrated a number of deficiencies in the design, which are associated with insufficient throughput and uneven distribution of flow rates in the discharge area of the waterfront. Conclusion The results demonstrated a practical importance of using mathematical simulation with numerical methods in a two-dimensional formulation, which allow us to consider processes in more detailed manner and change the hydraulic system design in a timely manner.

scholarly journals On the propagation of diel signals in river networks using analytic solutions of flow equations

2015 ◽  
Vol 12 (8) ◽  
pp. 8175-8220 ◽  
Author(s):  
M. Fonley ◽  
R. Mantilla ◽  
S. J. Small ◽  
R. Curtu
Keyword(s):  
Analytic Solutions ◽  
River Network ◽  
Low Flow ◽  
River Networks ◽  
Signal Delay ◽  
Flow Conditions ◽  
Flow Equations ◽  
Linear Transport Equation ◽  
Daily Evapotranspiration ◽  
Self Similar

Abstract. Two hypotheses have been put forth to explain the magnitude and timing of diel streamflow oscillations during low flow conditions. The first suggests that delays between the peaks and troughs of streamflow and daily evapotranspiration are due to processes occurring in the soil as water moves toward the channels in the river network. The second posits that they are due to the propagation of the signal through the channels as water makes its way to the outlet of the basin. In this paper, we design and implement a theoretical experiment to test these hypotheses. We impose a baseflow signal entering the river network and use a linear transport equation to represent flow along the network. We develop analytic streamflow solutions for two cases: uniform and nonuniform velocities in space over all river links. We then use our analytic solutions to simulate streamflows along a self-similar river network for different flow velocities. Our results show that the amplitude and time delay of the streamflow solution are heavily influenced by transport in the river network. Moreover, our equations show that the geomorphology and topology of the river network play important roles in determining how amplitude and signal delay are reflected in streamflow signals. Finally, our results are consistent with empirical observations that delays are more significant as low flow decreases.

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