This document provides an overview of topics to be covered in a 3-week professional engineering exam review session on hydrology and hydraulics. It will cover key aspects of hydrology including the hydrologic cycle, precipitation, runoff analysis using the Curve Number method, and peak discharge calculations. Hydraulics topics will include flow through common structures like weirs, orifices, and pipes. Example problems will be worked through for each major topic to illustrate concepts and calculations. Attendees are advised to review references and practice additional example problems.
Gradually varied flow is one kind of non uniform flow . Flow parameters such as depth of flow, flow velocity , discharge change with time and space gradually. Gradually varied flow is determined by the type of the channel bottom slopes. Flow profiles can be sustained in three different flow regions . This ppt covers only mild slope flow profile.
Deals with the primary treatment of sewage specially for the removal of suspended solids and also for the stabilization of the separated solids. treatment, design and performance details of primary clarifiers, anaerobic ponds, UASB reactors, UASB ponds, and baffled anaerobic reactors are covered in this presentation..
Gradually varied flow is one kind of non uniform flow . Flow parameters such as depth of flow, flow velocity , discharge change with time and space gradually. Gradually varied flow is determined by the type of the channel bottom slopes. Flow profiles can be sustained in three different flow regions . This ppt covers only mild slope flow profile.
Deals with the primary treatment of sewage specially for the removal of suspended solids and also for the stabilization of the separated solids. treatment, design and performance details of primary clarifiers, anaerobic ponds, UASB reactors, UASB ponds, and baffled anaerobic reactors are covered in this presentation..
L11 -SECONDARY TREATMENT OF SEWAGE - TRICKLING FILTERS.pptxPRACHI DESSAI
Wastewater treatment is a process used to remove contaminants from wastewater and convert it into an effluent that can be returned to the water cycle. Once returned to the water cycle, the effluent creates an acceptable impact on the environment or is reused for various purposes (called water reclamation).
OPEN CHANNEL FLOW AND HYDRAULIC MACHINERY
Open channel flow: Types of flows – Type of channels – Velocity distribution – Energy and momentum correction factors – Chezy’s, Manning’s; and Bazin formula for uniform flow – Most Economical sections. Critical flow: Specific energy-critical depth – computation of critical depth – critical sub-critical – super critical flows
Non-uniform flows –Dynamic equation for G.V.F., Mild, Critical, Steep, horizontal and adverse slopes-surface profiles-direct step method- Rapidly varied flow, hydraulic jump, energy dissipation
L1- INTRODUCTION TO WASTE WATER ENGINEERING.pptxPRACHI DESSAI
Wastewater treatment is a process used to remove contaminants from wastewater and convert it into an effluent that can be returned to the water cycle. Once returned to the water cycle, the effluent creates an acceptable impact on the environment or is reused for various purposes (called water reclamation).
Uniform Flow: Basic concepts of free surface flows,
velocity and pressure distribution,
Mass, energy and momentum principle for prismatic and non-prismatic channels,
Review of Uniform flow: Standard equations,
hydraulically efficient channel sections,
compound sections,
Energy-depth relations:
Concept of specific energy, specific force,
critical flow, critical depth,
hydraulic exponents, and
Channel transitions.
L11 -SECONDARY TREATMENT OF SEWAGE - TRICKLING FILTERS.pptxPRACHI DESSAI
Wastewater treatment is a process used to remove contaminants from wastewater and convert it into an effluent that can be returned to the water cycle. Once returned to the water cycle, the effluent creates an acceptable impact on the environment or is reused for various purposes (called water reclamation).
OPEN CHANNEL FLOW AND HYDRAULIC MACHINERY
Open channel flow: Types of flows – Type of channels – Velocity distribution – Energy and momentum correction factors – Chezy’s, Manning’s; and Bazin formula for uniform flow – Most Economical sections. Critical flow: Specific energy-critical depth – computation of critical depth – critical sub-critical – super critical flows
Non-uniform flows –Dynamic equation for G.V.F., Mild, Critical, Steep, horizontal and adverse slopes-surface profiles-direct step method- Rapidly varied flow, hydraulic jump, energy dissipation
L1- INTRODUCTION TO WASTE WATER ENGINEERING.pptxPRACHI DESSAI
Wastewater treatment is a process used to remove contaminants from wastewater and convert it into an effluent that can be returned to the water cycle. Once returned to the water cycle, the effluent creates an acceptable impact on the environment or is reused for various purposes (called water reclamation).
Uniform Flow: Basic concepts of free surface flows,
velocity and pressure distribution,
Mass, energy and momentum principle for prismatic and non-prismatic channels,
Review of Uniform flow: Standard equations,
hydraulically efficient channel sections,
compound sections,
Energy-depth relations:
Concept of specific energy, specific force,
critical flow, critical depth,
hydraulic exponents, and
Channel transitions.
In this ppt I present a method to estimate how much stormwater a catchment
area will produce, and how a drain can be sized to remove this water.
This method can be used to design a simple drainage system, or to determine
whether a proposed drainage system is realistic.
1
KNE351 Fluid Mechanics 1
Laboratory Notes
Broad-Crested Weir
This booklet contains instructions and notes for the experiment listed above.
Additional material relating to laboratory work will be delivered during the
course. The expectations regarding lab work and reporting are described in a
separate document,‘KNE351. FLUIDMECHANICS: Laboratory Method and
Reporting’, which will also be circulated at the beginning of the course. It is
expected that all students study these notes and complete the pre-lab component
prior to the laboratory session. An overview of the laboratory equipment will
be provided at the beginning of each session.
A D Henderson
2
1. Learning Objectives
1. Observe and understand the behaviour of a real fluid flowing over a broad-crested weir,
2. Model this behaviour employing the Continuity and Bernoulli (Energy) Principles to
predict the flow rate from depth measurements.
3. Evaluate these predictions by comparing with measured values and use Specific Energy
to explain the changing nature of the flow over the weir.
2. Introduction
The theory of non-uniform flow in channels is covered by the course text, by many other fluid
mechanics texts, and by several web sites.
The specific energy, E, is the energy at a channel cross-section referred to the base of the
channel (in contrast to the Bernoulli equation, which is referred to a fixed horizontal datum).
The expression given for E is actually an approximation valid for small bed slopes. You've
measured the flume slope, and should examine this approximation in your report. A hydrostatic
pressure distribution is assumed, and you should also examine the validity of this assumption. If
the streamlines are not parallel, then the accelerative forces will modify the pressure - depth
relationship.
In general, two conjugate flows depths satisfy the specific energy equation for a given value of
the specific energy. The greater depth is associated with subcritical flow, and the shallower
depth with supercritical flow. At the critical depth the conjugate depths are equal, and the
discharge for the given specific energy is a maximum.
Broad crested weirs are used as a method of flow measurement in open channel flows. If the
weir is sufficiently high and long, the free surface will drop to critical depth. If the height of
the upstream flow is measured, then the flow rate can be determined.
3
3. Apparatus
• Water flume comprising of pump, control valve, venturi and v-notch flow meters,
downstream control gate.
• depth gauges
• 2 vertical water manometers
• 2 total head tubes
4. Preparation
Examine and sketch the layout of the channel and associated flow measuring equipment.
Measure the channel width and note significant geometrical parameters of the nozzle venturi
meter and V-notch weir. Note the directions of readings of all measuring scales.
a. Measure the channel, weir dimensions, a.
Analytical modelling of groundwater wells and well systems: how to get it r...Anton Nikulenkov
Aquifer tests are probably the most widely used methods to obtain hydrogeological properties that are vital for any mine dewatering or environmental impact assessments. Numerous softwares and methods currently exist that provide quick and easy tests interpretation by fitting theoretical and measured drawdown curves. However, misinterpreting a-priory groundwater concepts and not accounting correctly for such factors as skin-effect, well storage or partial penetration may result in hydraulic conductivity errors by several hundred precents. As illustrated by case studies from WA, both numerical and analytical models generally suffer from non-uniqueness that can be overcome by understanding a-priory groundwater concepts and implementing them appropriately into the interpretation algorithms.
The presentation also discusses an analytical approach for well systems design. The methodology is presently incorporated in ANSDIMAT software package that is developed by the Russian Academy of Sciences. The method uses standard and research analytical solutions and it is based on the principle of superposition. Unlike numerical models, the method allows calculating drawdowns inside a pumping well and regional drawdowns, for example, on an open pit contour. A particle tracking component, incorporated into the methodology, provides a practical alternative to numerical models for simplified environmental impact assessments.
Macroeconomics- Movie Location
This will be used as part of your Personal Professional Portfolio once graded.
Objective:
Prepare a presentation or a paper using research, basic comparative analysis, data organization and application of economic information. You will make an informed assessment of an economic climate outside of the United States to accomplish an entertainment industry objective.
The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
The Roman Empire’s society was hierarchical, with a rigid class system. At the top were the patricians, wealthy elites who held significant political power. Below them were the plebeians, free citizens with limited political influence, and the vast numbers of slaves who formed the backbone of the economy. The family unit was central, governed by the paterfamilias, the male head who held absolute authority.
Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
Synthetic Fiber Construction in lab .pptxPavel ( NSTU)
Synthetic fiber production is a fascinating and complex field that blends chemistry, engineering, and environmental science. By understanding these aspects, students can gain a comprehensive view of synthetic fiber production, its impact on society and the environment, and the potential for future innovations. Synthetic fibers play a crucial role in modern society, impacting various aspects of daily life, industry, and the environment. ynthetic fibers are integral to modern life, offering a range of benefits from cost-effectiveness and versatility to innovative applications and performance characteristics. While they pose environmental challenges, ongoing research and development aim to create more sustainable and eco-friendly alternatives. Understanding the importance of synthetic fibers helps in appreciating their role in the economy, industry, and daily life, while also emphasizing the need for sustainable practices and innovation.
Embracing GenAI - A Strategic ImperativePeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
June 3, 2024 Anti-Semitism Letter Sent to MIT President Kornbluth and MIT Cor...Levi Shapiro
Letter from the Congress of the United States regarding Anti-Semitism sent June 3rd to MIT President Sally Kornbluth, MIT Corp Chair, Mark Gorenberg
Dear Dr. Kornbluth and Mr. Gorenberg,
The US House of Representatives is deeply concerned by ongoing and pervasive acts of antisemitic
harassment and intimidation at the Massachusetts Institute of Technology (MIT). Failing to act decisively to ensure a safe learning environment for all students would be a grave dereliction of your responsibilities as President of MIT and Chair of the MIT Corporation.
This Congress will not stand idly by and allow an environment hostile to Jewish students to persist. The House believes that your institution is in violation of Title VI of the Civil Rights Act, and the inability or
unwillingness to rectify this violation through action requires accountability.
Postsecondary education is a unique opportunity for students to learn and have their ideas and beliefs challenged. However, universities receiving hundreds of millions of federal funds annually have denied
students that opportunity and have been hijacked to become venues for the promotion of terrorism, antisemitic harassment and intimidation, unlawful encampments, and in some cases, assaults and riots.
The House of Representatives will not countenance the use of federal funds to indoctrinate students into hateful, antisemitic, anti-American supporters of terrorism. Investigations into campus antisemitism by the Committee on Education and the Workforce and the Committee on Ways and Means have been expanded into a Congress-wide probe across all relevant jurisdictions to address this national crisis. The undersigned Committees will conduct oversight into the use of federal funds at MIT and its learning environment under authorities granted to each Committee.
• The Committee on Education and the Workforce has been investigating your institution since December 7, 2023. The Committee has broad jurisdiction over postsecondary education, including its compliance with Title VI of the Civil Rights Act, campus safety concerns over disruptions to the learning environment, and the awarding of federal student aid under the Higher Education Act.
• The Committee on Oversight and Accountability is investigating the sources of funding and other support flowing to groups espousing pro-Hamas propaganda and engaged in antisemitic harassment and intimidation of students. The Committee on Oversight and Accountability is the principal oversight committee of the US House of Representatives and has broad authority to investigate “any matter” at “any time” under House Rule X.
• The Committee on Ways and Means has been investigating several universities since November 15, 2023, when the Committee held a hearing entitled From Ivory Towers to Dark Corners: Investigating the Nexus Between Antisemitism, Tax-Exempt Universities, and Terror Financing. The Committee followed the hearing with letters to those institutions on January 10, 202
2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
Adversarial Attention Modeling for Multi-dimensional Emotion Regression.pdf
2012 pe review__hyd_
1. 2012 PE Review:
IV-A: Hydrology and Hydraulics
Michael C. Hirschi, PhD, PE, D.WRE
Senior Engineer
Waterborne Environmental, Inc.
hirschim@waterborne-env.com
also Professor Emeritus
University of Illinois
2. Acknowledgements:
Daniel Yoder, I-A, PE Review 2006
Rafael (Rafa) Muñoz-Carpena, I-A, PE Review 2007-09
Rod Huffman, PE Review coordinator
3. Session Topics
• Hydrology
• Hydraulics of Structures
• Open Channel Flow
4. Hydrology
• Hydrologic Cycle
• Precipitation
– Average over Area
– Return Period
• Abstractions from Rainfall
• Runoff
– Hydrographs
– Determination methods
7. A few comments
• Material outlined is about 3 weeks or more in a
3-semester hour class. I’m compressing at least
6 hours of lecture and 3 laboratories into 2
hours, so I will:
– Review highlights and critical points
– Do example problems
• You need to:
– Review and tab references
– Do additional example problems, or at least
thoroughly review examples in references
12. Example 1
How do different calculation methods of rainfall average compare?
Consider:
13. Raingage data
• Gages (clockwise from upper left): 1.9”,
2.1”, 1.8”, 1.9”, 2.1”, 2.2”
Arithmetic average: 2.0”
14. Theissen Polygons
• Areas closest to each raingage
determined by perpendicular bisectors of
each line between raingages.
• Areas for each raingage, again clockwise
from upper left: 65ac, 150ac, 55ac, 140ac,
215 ac, 270ac
• Figure is repeated with Theissen polygon
construction added.
15. Why bisectors?
• When perpendicular bisectors are
constructed, they are, by definition, lines
that are equidistant from the points at the
ends of the lines they bisect.
• So, the combination of the constructions
delineate areas that are closest to a given
point (raingage in this case)
16. Is the watershed average
rainfall using the Theissen
Polygon method most nearly:
A. 2.0”
B. 2.1”
C. 2.2”
D. 1.9”
17. Theissen calculation
• Uses areal weighted average, so the sum of the
products of area x depth divided by total area
• Hint: If you measure the areas yourself, the
denominator should be the sum of the areas, not
the known watershed area
• So, average Theissen rain: Answer B, 2.1”
(65*1.9+150*2.1+55*1.8+140*1.9+215*2.1+270*2.
2)/(65+150+55+140+215+270)=2.07”, which is
best represented as 2.1” given most data is 2
significant digits.
19. Return Period (two descriptions)
• A 10 year-24 hour rainfall volume is that
depth of rainfall over a 24 hour period that
is met or exceeded, on the long-term
average, once every 10 years.
• Another way to describe it is the 24 hour
rainfall depth that has a 1 in 10 (10%)
chance to be met or exceeded each year,
on the long term average.
20. US 100yr-24hr Rainfall
100yr-24hr data from TP-40 (Hershfield (1961)
as referenced by Fangmeier et al. (2006)
21. Return Period Data
• Constructed from historical rainfall data
• Available in tabular form via website or
state USDA-NRCS reports.
• Available as national maps (similar to
previous slide) in several references such
as Haan, Barfield & Hayes (1994).
22. Example
A reservoir is to be designed to contain the
runoff from a 10yr-24hr rainfall event in
Northeastern Illinois. What rainfall
volume is to be considered?
A. 4.5”
B. 3.9”
C. 4.1”
D. Cannot estimate from available maps
26. Abstractions from Rainfall
• Abstractions from rainfall are “losses” from
rainfall that do not show up as storm water
runoff:
– Interception
– Evapotranspiration
– Storage
• In bank
• On surface
– Infiltration
27. Runoff by other names…
• “Effective” rainfall
• Rainfall “excess”
28. Runoff
If rainfall rate exceeds the soil infiltration
capacity, ponding begins, and any soil
surface roughness creates storage on the
surface. After at least some of those
depressions are filled with water, runoff
begins. Additional rain continues to fill
depressional storage and runoff rate
increases as more of the hill slope and
subsequently the watershed contributes
runoff.
30. Time of Concentration, tc
The time from the beginning of runoff to the
time at which the entire watershed is
contributing runoff that reaches the
watershed outlet is called the Time of
Concentration. It is also described as the
“travel time from the hydraulically most
remote point in a watershed to the outlet”.
36. Runoff Example
In a previous problem, a design rain event in NE
Illinois was determined to be 4.1”. Assuming the
watershed in question was a completed 300 ac
residential area with an average lot size of ½ ac,
all on Hydrologic Group C soils, what is the
needed pond volume, if all runoff is to be
retained?
A: 2.5 runoff-inches
B: 53 acre-inches
C: 630 acre-ft
D: 53 acre-ft
39. Answer to Runoff Example
The answer is D, 53 acre-ft. From the table,
the CN for Hyd group C soil with ½-ac lot
is 80. Using the graph with a 4.1” rainfall,
runoff depth is 2.1”. Volume is then
300ac*2.1in = 630 ac-in, divided by 12 is
53 ac-ft.
40. Additional example
You discover that the subdivision is actually 100
acres of ½ ac lots on C soils, 100 acres of ½ ac
lots on D soils, 50 acres of ¼ ac lots on B soils
and 50 acres of townhouses on A soils. What
CN value would you use?
A: 79
B: 85
C: 80
D: 75
42. Answer
The correct answer is C, 80. Use an area-weighted
average, similar to Theissen
method. The respective CN values for ½
ac on C, ½ ac on D, ¼ ac on B and
townhouses on A are 80, 85, 75 & 77.
The area-weighted CN is then
(80*100+85*100+75*50+77*50)/300 =
80.33, which is more appropriately 80.
43. Peak Discharge
The CN method also provides for Peak
Discharge estimation, using graphs or
tables. Required information includes
average watershed slope, watershed flow
path length, CN, and rainfall depth. The
graphical method from the EFM is:
45. Peak Discharge Example
Same residential watershed that produced
2.1” of runoff from a 4.1” rainfall. Flow
length is 2500’, slope is 2%. CN is 80, so
S is 2.5”. Ia = 0.2*S = 0.5”. Ia/P =
0.5/4.1=0.122.
Tc = 2500^0.8*(1000/80-9)^0.7/1140/2^0.5
=0.8hr
47. Example solution
From graph, with Ia/P of 0.122 and Tc of
0.8hr, unit peak discharge is 0.57 cfs/ac/in
or qp = 0.57*300*2.1 = 360 cfs
48. Rational Method
The Rational Equation is:
Qp = CiA
where:
C is a coefficient
i is rainfall intensity of duration tc
A is area in acres
C is approximately 0.4, A is 300ac, i is 2” in 30min, so 4iph,
peak rate is then 0.4*300*4 = 480 cfs
50. Hydraulics of Structures
Flow through structures is important given
that such structures control the rate of
flow. Sizing of such structures is then
important to allow flow to pass while
protecting downstream areas from the
effects of too high a flow rate. Structures
may also be used for measurement of
water flow. Each type of structure will
produce different types of flow depending
upon size and flow rate passing through it.
55. Example
• You are measuring flow using a 90° V-notch
weir. H is measured as 0.53’ at
2.5’ upstream of the weir. What is the
flow rate?
A. 230 gpm
B. 0.51 cfs
C. 0.51 gpm
D. A & B
56. Answer
• The answer is D. The equation from Haan
et al (1994) is:
57. Answer, continued
• Q = 2.5*H^2.5, where Q is in cfs and H is
in feet
• Q=2.5*(0.53)^2.5=0.511 cfs or 0.51 cfs
• Q=0.51 cfs*60sec/min*7.48gal/cf=230
gpm
• Note: Both answers contain 2 significant
figures
58. Orifice Flow
• Submerged vs Free Outlet
• Shapes affecting C
62. Example
• Markers Mark distillery just moved a 3’ diameter
barrel of their bourbon over their charcoal filter
bed to drain the bourbon into the system to be
bottled. The bung plug is removed
instantaneously, allowing barrel strength
bourbon to flow freely from the 2” diameter
bung, which can be considered a sharp-edged
orifice. What is the initial flow rate (assuming
same specific gravity as water, which is an
incorrect assumption)?
65. Pipe flow
When considering pipe flow in a structure,
Bernoulli’s equation is used:
Frictional losses are multiples of the velocity head (V2/2g)
and are additive.
66. Head loss under pipe flow
• Entrance loss (Ke)
• Bend loss (Kb)
• Pipe friction loss (Kc)
• Each coefficient is documented in references
Considering the Bernoulli equation for a spillway,
the pressure at entrance and exit is atmospheric,
the elevation difference is the water surface elevation
difference between upstream and downstream,
and the remaining term is the velocity head plus losses
69. Spillway considerations
A given spillway may have several
discharge relationships (weir, orifice, pipe)
depending upon the head (stage). The
stage discharge curve then becomes a
combination curve, with the type of
relationship allowing the highest flow at a
given head in control.
Consider a drop inlet control structure:
72. Example
An 18” CMP with an 18” vertical riser is used
as the principal spillway for a pond. The
pipe is 50’ long with one 90° bend. The
top of the inlet is 10’ above the bottom of
the outlet. Develop the stage-discharge
relationship assuming a free outfall.
73. Weir flow
Basic equation:
Given 18” riser, length of weir is 2πr, or 4.7’, so
74. Orifice flow
Basic orifice equation:
Given 18” riser and assuming C’ of 0.6,
75. Pipe flow
Basic pipe flow equation:
After looking up each parameter:
78. Open Channel Flow
Flow through open channels is another
important area to consider and review.
Velocity and flow rate are usually
calculated using Manning’s equation,
which considers flow geometry, channel
roughness and slope.
79. Manning’s Equation
Where:
V= flow velocity in fps
Rh = Hydraulic Radius in ft
S = Energy gradeline slope in ft/ft (=bed slope for normal flow)
n = Manning coefficient
1.49 = conversion from SI to English units
Hydraulic radius is the flow area divided by the wetted perimeter.
82. Example
What is the flow rate for a rectangular
finished (clean) concrete channel with a
base width of 8’, channel slope of 0.5%,
with a “normal” water depth of 2’?
A: 140 cfs
B: 8.5 cfs
C: 100 cfs
D: 200 cfs
83. Solution
n is 0.015, Rh is 8*2 sq.ft./(2+8+2) ft, S is 0.005 ft/ft, so
V = 8.5 ft/sec
Q = V*A= 8.5 ft/sec*16 sq.ft. = 140 cfs
84. Vegetated Waterway Design
The design of a vegetated waterway is an
iterative process, considering both
capacity when the grass is unmowed and
hence higher resistance to flow and
stability when recently mowed and more
susceptible to bed scour at high flow
velocities. Fortunately, the EFM has tables
of suitable channel dimensions.
86. Example
A subdivision produces a peak runoff rate of
60 cfs from a 10yr-24hr rainfall. A
vegetated waterway with an average slope
of 3% is to be planted with Kentucky
bluegrass. The soil at the waterway site is
easily eroded. The waterway will be
constructed with a parabolic shape. What
top width and depth are required (ignoring
freeboard)?