H y d r o C A D Stormwater Modeling System Version 7 Training Notebook First Edition Copyright 2005 HydroCAD Software Solutions LLC. All rights reserved. HydroCAD is a registered trademark of HydroCAD Software Solutions LLC. Other trademarks are the property of their respective owners. HydroCAD Software Solutions LLC P.O. Box 477 Chocorua, NH 03817 1-800-927-7246 Tel: (603) 323-8666 Fax: (603) 323-7467 www.hydrocad.net ISBN 978-0-913633-13-7 6135N rev. 8/11/05
Table of Contents Section 1 - Introduction to HydroCAD (27 slides)... 5 Section 2 - Hydrology (59 slides)...13 Section 3 - Time-of-Concentration (16 slides)...29 Section 4 - Pond Storage Calculations (36 slides)...35 Section 5 - Pond Outlet Hydraulics (52 slides)...45 Section 6 - Pond Routing (29 slides)...61 Section 7 - Routing Methods (14 slides)...71 Section 8 - Links (9 slides)...77 Section 9 - Printing and Data Management (14 slides)...81 Notes: This notebook includes printed copies of the HydroCAD Stormwater Training Slides. It is intended to be used in conjunction with live HydroCAD training seminars, or with the HydroCAD Stormwater Training Disk, which includes video clips and narration for each slide. The slides are arranged in nine sections, as listed above. Space for note-taking is provided on each page. Each slide is marked (in the lower-right corner) with the section number and slide number. For example, 5-180" indicates section 5, slide 180. For additional technical information on any of the topics covered in the slides, please refer to the HydroCAD Owner s Manual or visit www.hydrocad.net.
Section 1 Introduction to HydroCAD
HydroCAD Training Seminar Welcome to the HydroCAD Seminar PYour Trainer: Peter Smart Section 1: Introduction 35 Minutes PPresident, HydroCAD Software Solutions LLC PHydroCAD developer since 1986 Press Space, PageDown, or Click to advance. Press PageUp to reverse. Esc to exit. Right-Click for other options. PTechnical software developer since 1977 PSoftware & Physics background since 1973 Copyright 2004 HydroCAD Software Solutions LLC All Rights Reserved - Duplication Prohibited 1-010 Tip: To play a video again, click anywhere on the image 1-020 What We re Here to Learn Getting to Know Each Other Understanding & Using HydroCAD Who are you and why are you here? PSome basics of Hydrology & Hydraulics < A little theory is helpful in understanding your results PWhat can HydroCAD Do? < Using the software to best advantage PSolving problems with HydroCAD < When to use HydroCAD < When not to use HydroCAD PHow many of you already use HydroCAD? PHow many of you review HydroCAD projects? PWhat are your objectives for today? PI am here to help you solve problems < Please interrupt with any questions! 1-030 1-040
Today s Schedule Getting Ready! 8:15-12:00 Morning Session 1-Introduction 2-Hydrology 3-Time-of-Concentration 4-Pond Storage! 12:00-12:45 Lunch! 12:45-4:30 Afternoon Session 5-Pond Outlets 6-Pond Routing 7-Routing Methods 8-Links 9-Printing & Data Management 10-Wrap-up and Closing Comments 1-050 A few notes before we continue PMake sure you have all hand-outs < HydroCAD Owner s Manual < HydroCAD Folder Each section is numbered We are on section 1 now POther announcements < Where are the bathrooms? PContinue with HydroCAD introduction < (Next slide) 1-060 A Solution for Every Budget For students, reviewers, & design professionals Understanding the Node Capacity PFree HydroCAD Sampler < Can open any HydroCAD project < Good for reviewers and educational use < Installed on lab computers today < But not recommended for actual design work! PComplete HydroCAD programs from just $195 < All programs have same features < Increase your node capacity at any time < Special pricing for additional users at same site PFor details please visit www.hydrocad.net 1-070 Pricing is based on the number of nodes you can save PHydroCAD can open projects of any size < Even if it exceeds your node capacity! PBut you cannot save an oversized project < To save, you must eliminate nodes, < Or upgrade to a larger capacity PFree Sampler can open projects of any size < But can only save up to 5 nodes < Also has 60-minute limit per session < Can stop and restart as required 1-080
Are you using the latest release? HydroCAD is updated approximately once a year HydroCAD Support Technical support and software updates PHydroCAD 7.0 is current release < For details visit www.hydrocad.net < Also includes CD reference library PUpdates are just $195 (for the first user) < Updates for additional users are half price PTo check your current version: < Start HydroCAD < Select Help Check for Update PFree web and email support for all customer < Email usually answered within the hour PPrime Support plan for $120 per year (1 license) < Provides unlimited telephone support PDeluxe Support plan for $240 per year (1 license) < Adds free program updates, including major releases < Free replacement of damaged or lost materials PFor details please visit www.hydrocad.net 1-090 1-100 Software Exercises Exploring basic HydroCAD operations PBefore we begin the initial software demonstration, are there any questions? PIf you wish, you may perform the following exercises yourself, or just watch the demo. Are You Ready? Make sure your computer is prepared for the exercises PIs your computer logged-in? < The windows desktop should be visible PCan you locate the HydroCAD shortcut? < HydroCAD icon should be on the desktop < Otherwise look in Start Programs HydroCAD PDoes anyone need help? 1-110 1-120
Getting Started HydroCAD is quick and easy to use Changing the Rainfall HydroCAD is quick and easy to use PA quick example < Start HydroCAD Click Start Programs HydroCAD HydroCAD -or- Click HydroCAD icon on desktop Skip the tutorial for now - but please do it later! < Open Mountain View Housing Complex Note Capacity Exceeded warning for Sampler < Open a report window Double-click any existing node (try Pond 3P) Calculations are performed automatically PChanging the Rainfall < Locate the Event Selector on the tool-bar < Click the Event Selector and select 10-year < Results are automatically updated for new rainfall 1-130 1-140 Editing a Node HydroCAD is quick and easy to use Report Windows Used to display live results & other capabilities PEditing a node < Right-click subcat 22S and select Edit < Click the Area tab < Change the first area to 20 acres < Click OK < Calculations & reports are automatically updated PRe-size & position reports as desired PUse tabs to view desired report PRight-click any table or graph for options < Change defaults on Settings General menu PUse buttons for special operations POpen multiple report windows as needed < Make sure the diagram doesn t hide the reports 1-145 1-150
Message Window Don t overlook this important information! PMessage Window opens automatically < Whenever new messages are generated PClick any message for details < 400+ pages of help, including equations PUse buttons for special operations < Show-all will recall previous messages Main HydroCAD Window How it works and what you can do with it PPrimary elements < Routing diagram - center screen < Palette - left of diagram < Tool bar - above the diagram Includes the Event Selector < Menu bar - above the tool bar < Title bar - at top of window < Project selector - below routing diagram < Status line - at bottom of window 1-160 1-170 Viewing the Routing Diagram Adjust the view to suit your needs PSeveral ways to scroll the display: < Drag the scroll bars < Click the scroll bar arrows < Drag the mouse wheel < Use the Diagram menu PZooming the display: < Mouse wheel < Zoom buttons on tool bar < Use the diagram menu Working with the Routing Diagram The diagram controls all the calculations PPointing to a node < Status line & tool-tip show more info PMoving a node < Just drag the node PChanging the routing < Drag the outflow arrow-head or handle < Arrow will move as you point to valid nodes 1-180 1-190
Creating & Deleting Nodes The diagram controls all the calculations PCreating a node < Drag from the palette onto the diagram -or- < Use Ctrl-drag to clone an existing node PDeleting a node < Right-click and select delete < -or- select node and use the tool bar button Special Diagram Operations The diagram controls all the calculations PCopy, Cut, and Paste nodes < Use standard windows shortcuts: Ctrl-C to Copy Ctrl-X to Cut Ctrl-V to Paste < See tutorial and help system for details PSelecting multiple nodes < Drag a selection rectangle around the nodes < All selected nodes can be moved, cut, etc. 1-200 1-210 Opening Multiple Projects You can have several projects open at the same time! POpen a second project: < Select Project Open from the menu < Select the TR-20 Sample Job Can also open any project from Windows PThe Project Selector shows all open projects < Select another project from the selector < Diagram and reports change automatically! Working with Multiple Projects You can have several projects open at the same time! PCan drag nodes between projects < To move, drag node to project selector < Use Ctrl-drag to drag a copy of any node < Projects can be Read-Only for automatic cloning... PUsing templates from a node library < Select Project Open < Select the Node Library #1" < Drag a node to another project Note automatic cloning! 1-220 1-230
Special Diagram Capabilities Node Numbers, Names & Notes Powerful capabilities you may not need every day Using them effectively to create clear reports PBackground image < Note logo on Mountain View Housing Complex < Can also use terrain image or site plan < EMF or BMP formats (JPEG coming soon) POther diagram settings < Open Diagram Settings screen < Select Show Grid and Snap to Grid < X-Y grid is now visible < Nodes snap to grid as moved 1-240 PNode Number < Appears inside each node < May include text, but keep it short! PNode Name < Appears below each node < Medium length (a few words) PNode Notes < Appear only in reports < Can be any length - use freely! 1-250 *** End of Section *** A few notes before we continue PThis completes the basic introduction to HydroCAD PAre there any other questions? PIf you performed the exercises, please close HydroCAD at this time. < Close HydroCAD (Use the upper X ) < Do NOT save your changes PContinue with next section: Hydrology 1-260
Section 2 Hydrology
Section 2: Hydrology Generating a runoff hydrograph 85 Minutes Press Space, PageDown, or Click to advance. Press PageUp to reverse. Esc to exit. Right-Click for other options. Copyright 2004 HydroCAD Software Solutions LLC All Rights Reserved - Duplication Prohibited 2-010 Introduction What are we going to discuss? PWe will start with a review of some fundamental hydrologic techniques. PA basic understanding of these calculations will improve your ability to understand and interpret the results from any hydrology software. PPlease see other texts for full details, such as the HydroCAD Owner s Manual. 2-020 What is the Return Period? A common point of confusion! P Roughly speaking, the return period is the average time between occurrences of a given event, such as the 25-year storm. P To be more precise, a 25-year storm has a 4% probability of occurring in any given year. P Therefore, a 25-year storm can occur in two consecutive years! 2-030 Intensity-Duration-Frequency Data A basic way to quantify rainfall observations. Typically compiled for each county in the US. 20 18 16 14 12 10 8 6 4 2 Frequency (years) 0 10 20 30 40 50 60 Rainfall Duration (minutes) P An IDF curve indicates the rainfall intensity that will occur for a given duration and return period. P The rainfall intensity remains constant for the entire duration. 100 50 25 10 5 2 Typical IDF Curves 2-040
The Rational Method A basic equation for predicting peak runoff Q ' CIA PQ=Peak Runoff [CFS] PC=Runoff Coefficient Pi=Rainfall intensity PA=Catchment Area < The intensity is determined from the IDF curve, but what duration do we use? Setting the Rainfall Duration for the Rational Method A simple equation gets more complicated! P We must use the critical duration, which produces the highest runoff. P For a single, homogeneous subcatchment, the duration is typically equal to the time-ofconcentration, Tc. P But when several subcatchments are combined, the critical duration can be any value between the shortest and longest Tc. 2-050 2-060 Other Limitations of the Rational Method The SCS Rainfall Distributions Allowing the rainfall intensity to vary over time PThe Rational Method predicts peak runoff, but not total runoff volume. PThe Rational Method predicts a constant flow, rather than generating a complete hydrograph. PRational Method is poorly suited for volumesensitive calculations, such as detention ponds. < How do we overcome these limitations??? P A mass curve indicates the cumulative rainfall depth at any time during the storm. 2-070 2-080
Features of Rainfall Distributions More Rainfall Distribution Features P Allows the intensity to vary over time. < Similar to an actual rainfall event P Includes rainfall volume of entire (24-hour) event. < Can be used for volume-sensitive calculations. P Each curve includes all events up to 24-hours. < Eliminates need to identify the critical duration! P Represents most of the US with just a few curves. < Curve is scaled for your local 24-hour rainfall depth. P Synthetic rainfalls provide design standards < Type II peak defined at 12 hours P Can also create an actual rainfall distribution < Allows modeling of observed events 2-090 2-100 The SCS Runoff Equation How much of the precipitation appears as runoff? 2 (P&.2 S) Q ' (Q=0 if P<.2S ) P %.8S where S ' 1000 & 10 CN PQ=Precipitation excess (runoff) [inches or mm] PP=Cumulative precipitation [inches or mm] PS=Potential maximum retention [inches] PCN=SCS Curve Number 2-110 Time-of-Concentration: What does it mean? Determining when the runoff occurs P The Tc is the time required for a particle of water to travel from the most hydrologically remote point in the watershed to the point of collection. P There are many procedures for calculating Tc < TR-55 Sheet Flow < TR-55 Shallow Concentrated Flow < Channel Flow (based on Manning s velocity) < Upland Method < CN Method (a.k.a. Lag Method) We ll examine the individual procedures in the next section 2-120
The SCS Dimensionless Unit Hydrograph Defines the runoff hydrograph for a single burst Unit Hydrograph Time Axis How long does the runoff last from a single burst? T p ' 5D and T p ' 2 3 T c ˆ D ' T c 7.5 < Tp=Time to peak < D=Burst duration < Tc=Time of concentration P Everything is based on the Tc 2-130 2-140 UH Time Axis Example Just substitute the Tc! 0 If Tc = 30 minutes D = Tc/7.5 = 4 minutes Tp = 5D = 20 minutes Tb = 5Tp = 100 minutes 20 40 60 80 100 Time (minutes) 2-150 Unit Hydrograph Flow Axis What is the peak runoff from a single burst? q p ' C K A Q ' 484 A Q ' 484 A Q T p T 2 p T 3 c Pq p =Peak discharge [CFS] PC=Units conversion factor (653.33) PK=UH Shape Factor (0.75 for SCS UH) P484=SCS UH Peak Factor PA=Area [sq-miles] PQ=Precipitation Excess (runoff) [inches] 2-160
UH Flow Axis Example A Fully Dimensioned UH! Determine the flow for a single burst, with precipitation excess Q If Q= 0.2 inch and A = 0.1 sq-mile and Tc = 0.5 hours q p = 484 A Q / 2/3Tc = 29 cfs The actual runoff hydrograph from a single burst of rainfall PNow we have a complete hydrograph for one burst. PBut how do we get the hydrograph for an entire 24-hour storm? 0 20 40 60 80 100 Time (minutes) 2-170 0 20 40 60 80 100 Time (minutes) 2-180 Convolution: The Heart of TR-20 Constructing the entire runoff hydrograph P The unit hydrograph (when dimensioned) tells us the runoff for a single burst of rainfall. P To determine the runoff for the entire storm, we must perform a convolution of the unit hydrograph with the precipitation excess. < We must break the storm into a sequence of individual bursts, and add up the hydrographs from all the bursts. Convolution: Step #1 Adding up the hydrographs for each burst 1) Divide storm into bursts D 2-190 Time (hours) 2-200
Convolution: Step #2 Adding up the hydrographs for each burst Convolution: Step #3 Adding up the hydrographs for each burst Total Hydrograph 3) Add all UH 1) Divide storm into bursts D 2) Generate UH for each burst 1) Divide storm into bursts D 2) Generate UH for each burst Time (hours) 2-210 Time (hours) 2-220 Complete Runoff Hydrograph Why does the hydrograph look like this? Performing the Convolution A computation-intensive process 2) Runoff peaks after rainfall peak 1) Zero runoff for several hours 3) Runoff continues after end of storm P If Tc = 7.5 minutes < Then burst duration D = 1 minute < And 24-hour storm contains 1440 bursts P If UH consists of 100 coordinates < 1440 x 100 = 144,000 coordinates must be calculated and summed to generate the runoff hydrograph!! P Calculation is not feasible by hand! Time (hours) 2-230 2-240
TR-55 and the Tabular Method TR-55 Warnings Doing runoff calculations by hand Quoting from the TR-55 manual P The TR-55 Tabular method allows manual calculation of a runoff hydrograph that approximates the TR-20 UH procedure. P TR-55 tables were produced by TR-20 with: < Curve Number = 75 < Runoff = 3 inches < Fixed Tc values from 0.1 hours to 2.0 hours P Other values require approximation and results will differ from actual TR-20 results. 2-250 P This method (TR-55) approximates TR-20, a more detailed hydrograph procedure... Use TR-20 if the watershed is very complex or a higher degree of accuracy is required. P The procedure (TR-55) should not be used to perform final design if an error in storage of 25 percent cannot be tolerated... More detailed hydrograph development and routing will often pay for itself through reduced construction costs. 2-260 HydroCAD: An Easier TRS20 Solution Plus lots of other calculations and capabilities P In 1986, HydroCAD was the first PC-based program to use the full UH runoff procedure. P Eliminates approximations in the tabular method. P Also provides: < TR-55 Tc procedures < Hydraulics calculations < True hydrograph routing < Lots more! (As we ll see throughout the day) P But first, let s examine some basic concepts in more detail... 2-270 What is a hydrograph? The flow of water over time (Flow vs. Time) T i m e A hydrograph is ideally a smooth curve... 2-280
But how do we represent the hydrograph curve numerically? Use a series of points spaced equally in time What is the peak flow? HydroCAD uses an interpolated peak, just like TR-20 P True peak may fall between points... P So interpolate using three highest points T i m e The time increment is called dt 2-290 T i m e Allows for variations in point timing 2-300 What time increment should I use? The time increment (dt) specifies the point spacing P For best results, use dt # Tc / 2 < This ensures good peak definition P If Tc $ 0.1 hours (6 minutes), use dt = 0.05 hours < This is the default value for new projects P A warning will occur if dt is too large < This will occur if Tc < 0.1 hours P Dt can be as small at 0.01 hours < For fastest operation, don t go smaller than required 2-310 What time span should I use? Long enough to cover all flow of interest! Default time span 5-20 hours Use longer span if entire volume is required! 0 3 6 9 12 15 18 21 24 T i m e (hours) 2-320
Rational Method hydrographs Time for a quick stretch! A shorter time span and time increment are required Default dt = 0.01 hours P Please have a quick stretch at your desk P We ll have a full break after this section 0 Tc D D+Tc D+2Tc Default time span = 0-3 hours 2-330 2-340 Rainfall Curves #1 Different ways to define the rainfall distribution Rainfall Curves #2 Different ways to define the rainfall distribution True Rainfall Mass Curve P The actual rainfall distribution is a curve P How do we represent this in HydroCAD? Fitted Mass Curve P Uses a polynomial fit to each segment for a true curve P Used for standard SCS rainfalls P For details see Start Programs HydroCAD Rainfall Info Time (hours) 2-350 Time (hours) 2-360
Rainfall Curves #3 Different ways to define the rainfall distribution Rainfall Curves #4 Different ways to define the rainfall distribution Mass curve points P Easy to define P Line segments may cause runoff steps Intensity curve points P Easy to define P Gives smooth runoff curve P Smoothing option gives better curve Time (hours) 2-370 Time (hours) 2-380 Sample Mass Curve File Sample Intensity Curve File This is all you need to create a custom mass curve This is all you need to create a custom curve timeunits=hours duration=1 1-hour duration timeunits=hours duration=1 1-hour duration depthunits=inches stormdepth=2.5 2.5 inch depth depthunits=inches stormdepth=2.5 2.5 inch depth depth= 0.020.080.200.410.625 depth=.805.915.985.995 1.000 Mass-curve points For full details see HydroCAD Sample B file 2-390 inten= 0.20.60 1.2 2.1 2.15 Inten= 1.8 1.1.7.1.05 Intensity-curve points For full details see HydroCAD Sample A file 2-400
Changing the Storm Duration HydroCAD can rescale a storm to any duration Tc Effects #1 How does the Tc effect the runoff hydrograph? Rescaled 12-hour storm Original 24-hour storm P Storm duration can be changed < But beware of change in peak P Different rainfall distribution may be required! P If Tc=0, runoff is immediate! < HydroCAD will accept Tc=0 P Hydrograph has same timing as rainfall distribution < Peak runoff occurs at same time as peak rainfall Time (hours) 2-410 0 6 12 18 24 30 36 42 48 Time (hours) 2-420 Tc Effects #2 How does the Tc effect the runoff hydrograph? PAs the Tc increases: < Unit Hydrograph is extended < Runoff occurs later Curve Number Effects How does the CN effect the runoff? PLow CN values decrease the runoff volume < Runoff timing is not directly effected by CN PHigh CN values increase the runoff volume < If CN=100 all precipitation will appear as runoff: Maximum Potential Retention = S ' 1000 & 10 ' 0 CN No Retention! 0 6 12 18 24 30 36 42 48 Time (hours) 2-430 SCS Runoff Volume = Q' (P&.2 S)2 P P %.8S ' All precip is runoff! 2-440
Rainfall on the surface of a pond How do we include this precipitation in the model? P Include pond surface area in an adjacent subcatchment. < OK for small pond areas P Or, model as separate subcat with: < Tc=0 < CN=100 < Produces Runoff equal to rainfall Adding Hydrographs What happens when multiple hydrographs are combined? 7 Combined Flow 7 Inflow #2 7 Inflow #1 P Peak flows add directly only if they occur at the same time! P Volumes must always add-up 2-450 T i m e 2-460 Software Exercises Exploring these topics in HydroCAD P Before we begin the software demonstration, are there any other questions about runoff calculations? P If you wish, you may perform the following exercises yourself, or just watch the demo. Are You Ready? Before we begin the exercises... P Is your computer logged-in? < The windows desktop should be visible P Can you locate the HydroCAD shortcut? < HydroCAD icon should be on the desktop < Otherwise look in Start Programs HydroCAD P Does anyone need help? 2-470 2-480
Subcatchment Setup #1 Prepare a subcatchment to receive our sample data P Getting ready < Start HydroCAD < Open the TR-20 Sample Project P Create a subcatchment: < Drag a subcat from the palette P Edit the subcatchment < Double-click the node -or- < Right-click and select Edit from the menu 2-490 Subcatchment Setup #2 Enter some sample data P Enter a couple of sub-areas & curve numbers: < Click the Area tab < Enter an area and a CN value directly For example: Area=10 acres, CN=75 < Enter a second area and lookup the CN value To open the lookup table, double-click the line Select the desired CN value from the table P A few notes about data entry tables < Right-click any table for options < Drag first column to change order of rows 2-500 Subcatchment Setup #3 Enter some sample data PEnter some Tc values: < Click the Tc tab < Do a direct Tc entry Double-click a blank line Select Direct Entry Enter a TC value of 20 minutes Click OK to save the TC data PWe ll examine the other Tc options later Subcatchment Setup #4 View the results! P Click OK to save the subcat data P Open a report window: < Double-click any described node -or- < Right-click and select report 2-510 2-520
Subcatchment Setup #5 View the results! P Explore the report tabs: < Hydrograph Tabular view Note maximum values in bold Click Shrink to see more points < Summary Use summary to review results and input data Click any line for help (new 7.1 feature) Rainfall Settings #1 Global settings for the current project P Review the calculation settings < Click the Calculator icon Note: You can leave any report windows open! P Runoff methods < TR-20 / SCS UH < SBUH < Rational P (We ll return to the routing options later) 2-530 2-540 Rainfall Settings #2 Global settings for the current project P Rainfall data < Rainfall distribution & depth < Antecedent moisture condition < Rainfall duration < Back-to-back storms P Rainfall events < Define events as desired < -or- import events from another project P For Rational Method: < Can define Custom IDF curves Rainfall Settings #3 Global settings for the current project P Time Span & Time Increment < Adjustable in response to any warning messages < Fast Hydrograph Plots generally recommended Improves plot speed and appearance Does not affect accuracy of calculations P Unit Hydrograph selection < Changing the Peak Factor 2-550 2-560
Rainfall Settings #4 Global settings for the current project Rainfall Settings #5 Global settings for the current project P Advanced Parameters < Initial Abstraction ratio < Used with new modeling techniques < (New feature added in version 7.1) P Automatic pipe & culvert sizing < Lots of options to explore on your own < Remember: Click HELP for more information P Click OK to close the calculation settings < Repots are updated for new settings! 2-570 2-580 *** End of Section *** P Before we move on, are there any other questions about subcatchments? P If you performed the exercises, you may close HydroCAD at this time. < You do NOT need to save your changes. P We will continue after a SHORT BREAK 2-590
Section 3 Time-of-Concentration
Section 3: Time of Concentration Different techniques for different applications 35 Minutes Press Space, PageDown, or Click to advance. Press PageUp to reverse. Esc to exit. Right-Click for other options. Introduction What are we going to discuss? PThere are many different techniques for calculating the time-of-concentration PHydroCAD incorporates a number of options PThe specific techniques you use will depend on project conditions and local requirements PLet s take a brief look at the HydroCAD procedures... Copyright 2004 HydroCAD Software Solutions LLC All Rights Reserved - Duplication Prohibited 3-010 3-020 TR-55 Sheet Flow For the head of a watershed TR-55 Shallow Concentrated Flow Generally used in combination with Sheet Flow PFor flow over plane surfaces at the head of a watershed POften limited to 100 feet, but never over 300 < Distance should be determined by visual inspection < Length is often critical to overall subcat Tc PShallow concentrated flow < For the transition between sheet flow and channel flow < Employs a velocity factor Kv Paved Surfaces: Kv = 20.33 fps Unpaved Surfaces: Kv = 16.13 fps PUpland Method < Same equation as Shallow Concentrated flow < But uses a wider range of Kv values As low as Kv = 2.5 fps for Forest with heavy litter 3-030 3-040
Channel Flow Often combined with Sheet Flow and Shallow Concentrated flow Curve-Number Method For calculating Tc on a larger scale PFor Manning s flow in defined channels PSeveral entry modes: < From TR-55 worksheet: Hydraulic Radius Cross-sectional flow area < HydroCAD will also calculate specific geometry: Rectangular/Vee/trapezoidal channel Circular channel (pipe) Parabolic channel 3-050 PDesigned to calculate Tc when specific flow conditions are not known PSimplified data requirements: < Curve Number < Hydraulic Length of watershed < Average watershed slope (not hydraulic length slope!) PRequires care in calculating average slope < Apply grid to watershed -or- < Use contour line procedure (in HydroCAD) 3-060 Direct Tc Entry If you already know the Tc PIf you already know the Tc, you can enter it directly PGenerally used when the Tc has already been calculated in another program PFor more complete reports you may enter: < Flow length < Flow velocity Software Exercises Exploring these topics in HydroCAD P Before we begin the software demonstration, are there any other questions about Tc calculations? P If you wish, you may perform the following exercises yourself, or just watch the demo. 3-070 3-080
Software Tc Exercises #1 Setting up a subcatchment for the Tc data P Getting ready < Start HydroCAD < Open TR-20 Sample Project P Prepare a new subcatchment: < Drag a subcat from the palette < Edit the subcatchment < Enter a single area Select the Area tab Enter Area = 10 acres Enter CN = 75 Software Tc Exercises #2 Exploring the Tc options P Create a flow segment for each Tc procedure < Select the Tc tab < Double-click any blank Tc line < Select a Tc procedure < Lets look at each Tc option... 3-090 3-100 Software Tc Exercises #3 Exploring the Tc options P Create a Sheet Flow segment: < Double-click a blank Tc line < Select Sheet Flow & click OK < Set the following values: Surface description = Grass: Short N value is supplied automatically Flow Length = 100' P 2 = 2.5" Land Slope =.01 ft/ft < Click OK to see the resulting Tc Software Tc Exercises #4 P Now try Shallow Concentrated Flow: < Double-click a blank Tc line < Select Shallow Concentrated Flow < Set the following values: Surface description = Unpaved K V is supplied automatically Flow Length = 100' Watercourse Slope =.01 ft/ft < Click OK to see the resulting Tc 3-110 3-120
Software Tc Exercises #5 Exploring the Tc options P Create a Channel Flow segment: < Double-click a blank Tc line < Select Trap/Vee/Rect Channel < Set the following values: Bottom Width = 4' Flow Depth = 2' (guesstimate) Left & Right Side Slope (Z) = 2 Channel Slope =.01 ft/ft N =.02 Length = 100' < Click OK to see resulting Tc Software Tc Exercises #6 Exploring the Tc options P Now try Lag/CN Method: < Double-click a blank Tc line < Select Lag/CN Method & click OK < Set the following values: Flow Length = 100' Land Slope =.01 ft/ft < Click OK to save data Lag/CN segments are not calculated yet Since they also require the area and CN 3-130 3-140 Software Tc Exercises #7 Exploring the Tc options P Click OK to save entire subcat P View the results: < Open a report Double-click the node < Review the Summary report < Note the Tc calculation table Note the relative Tc of each flow segment Note velocity of each section Channel capacity is also shown < To make any changes: Just click Edit button 3-150 *** End of Section *** P Before we move on, are there any other questions about Tc calculations? P If you performed the exercises, you may close HydroCAD at this time. < You do NOT need to save your changes. 3-160
Section 4 Pond Storage Calculations
Section 4: Pond Storage Defining and calculating pond storage 55 Minutes Press Space, PageDown, or Click to advance. Press PageUp to reverse. Esc to exit. Right-Click for other options. Pond Storage Introduction Defining a volume that can fill with water P Most ponds require a description of their storage capability P HydroCAD provides many options for defining pond storage... Copyright 2004 HydroCAD Software Solutions LLC All Rights Reserved - Duplication Prohibited 4-010 4-015 Pond Storage Calculations HydroCAD provides many techniques Prismatoid Storage A volume with a rectangular base & four equally sloped sides Prismatoid Cone/Cylinder Horizontal Cylinder Parabolic Arch Prefab Chamber Custom Storage P Defined by: < Base width & length < Height < Side Z (Run/Rise) Set Z=0 for vertical sides PUsed for: < Rectangular vaults < Some excavations 1 Z Let s review each of these options... 4-020 4-030
Vertical Conic Storage A volume with a circular base & any side slope P Defined by: < Bottom diameter < Height < Side Z (Run/Rise) Set Z=0 for vertical sides P Used for: < Circular dry-wells < Catch basins < Circular excavations 4-040 Horizontal Cylinder Storage For a circular tank or pipe storage P Defined by: < Diameter < Length < Slope (0 if level) Slope feature added in upcoming HydroCAD 7.1 P Used for: < Pipe storage < Pipe embedded in stone Details coming up later! 4-050 Parabolic Arch Storage For an (underground) parabolic arch P Defined by: < Bottom width < Height < Length P Used for: < Generic chamber storage < Can be embedded in stone Details coming up later! 4-060 Prefab Chamber Storage For specific prefabricated storage chambers P Defined by: < Specific chamber data CULTEC data pre-defined Other chambers can be added < Length Preset for specified chamber P Used for: < Precise chamber storage < Can be embedded in stone Details coming up later! 4-070
Custom Pond Storage Multiple options for any other type of storage! P 1) Enter cumulative storage directly < Useful if you already have the data < But does not allow area calculations P 2) Enter incremental storage < HydroCAD adds all the slices to determine the cumulative storage P 3) Enter surface area at each stage < Storage is calculated automatically < Several options for volume calculation... Storage by Surface Area #1 Several methods for converting surface area to storage P Prismatic Sections < Horizontal sections of a prism May have 0, 1 or 2 sloped sides < Uses average area method P Pyramidal Sections < Square base < Sloped or vertical sides A 2 A 1 A 2 A 1 4-080 4-090 Storage by Surface Area #2 Several methods for converting surface area to storage P Conic Sections < Circular base < Sloped or vertical sides P Irregular Sections < Same volume as conic sections < Accurate wetted area for elongated shapes A 2 A 1 A 2 A 1 Compound Storage Each pond can use multiple storage definitions PAll defined volumes are added together < Water surface elevation must be same in all PCan use any combination of storage < For example, one pond could include: Parabolic arch (underground storage) Vertical cylinder (connection to surface) Custom storage (above-grade storage) + + 4-100 4-110
Pond Storage Multiplier Prevents duplication of storage definitions PThe Storage Multiplier makes it easy to model several identical volumes < All volumes must be at same elevation < & have same water surface elevation Setting the Voids Allowing for reduced storage PVoids allows for reduced storage < Adjusts for sand, gravel, or stone fill PMaintains overall wetted-area for exfiltration X 2 = + X 70% voids = 4-120 4-130 Embedded Storage Example #1 A simple combination of basic features PPerforated pipes in a stone bed < First define the outer stone bed Use any standard storage definition (prismatoid, etc.) Set the correct void ratio for the backfill < Then define the inner storage volumes(s) Set each chamber to Embed in the outer storage Embedded Storage Example #2 Complex storage setups are quick and easy PCombine different shapes < You can even include the connectors... < And any above-grade storage! 4-140 4-150
Embedded Storage Example #3 Complex storage setups are quick and easy PUse any desired configuration < Different pipes at different elevations < Varying backfill with different void ratios Level Pool Storage All volumes within a single pond must maintain the same water surface elevation! P Can equalize through perforations P -or- by direct connections 4-160 4-170 Overfilled Storage All storage definitions are closed P What happens when a storage volume fills up? < HydroCAD-7 no longer extrapolates storage < YOU must define any overflow storage < Otherwise the storage volume is capped and head (pressure) will be developed This allows modeling of closed storage volumes Overflow Storage If you wish to avoid a pressurized situation, you must define any active overflow storage 4-180 Any road culvert may cause ponding Consider each culvert as a possible pond P Any point in your model that may detain water is considered to be a pond P For a road culvert, the pond storage is the area that would be inundated at the inlet P This storage must be known in order to accurately determine the culvert headwater, and hence the flow 4-185
Zero-Storage Ponds Why have a pond with no storage? PFor modeling ponds with insignificant storage < Such as catch basins PSince there is no storage: Qout = Qin < No storage = no detention! PSo what good is a zero-storage pond? < Makes it easy to model catch basins Just enter the culvert outlet, plus any other devices < Indicates the headwater (HGL) on outlet devices Can be used as the tailwater for upstream nodes! 4-190 Software Exercises Exploring these topics in HydroCAD PBefore we begin the software demonstration, are there any other questions about pond storage calculations? PIf you wish, you may perform the following exercises yourself, or just watch the demo. 4-200 Getting Started Prepare a new project file Prepare a New Pond Each pond contains storage information P Get ready: < Start HydroCAD < Create a new project called Seminar1 If the project already exists, delete the old file first P Prepare a pond to receive the storage data: < Drag a pond from the palette < Edit the pond < Select the Detention Pond option < Select the Storage tab < Remove check from Large Units This allows us to use Cubic-Feet instead of Acre-Feet 4-210 4-220
Pond Storage Options #1 Pond Storage Options #2 Exploring the pond storage options Exploring the pond storage options P Explore the storage options: < (You should already be on the Storage tab) < Double-click a blank storage line < Enter a new storage definition: Select Prismatoid and click OK Invert elevation = 100' Width = 10' Length = 20' Height = 10' < Click OK to save the prismatoid definition 4-230 P Lets add some more storage: < Vertical cone or cylinder Description = Drywell Invert Elevation = 100' Diameter = 10' Height = 8' < Horizontal cylinder Description = Pipe Storage Invert Elevation = 102' Diameter = 48" Length = 100' 4-240 Pond Storage Options #3 Pond Storage Options #4 Exploring the pond storage options Exploring the pond storage options P Lets add some more storage: < Parabolic arch Invert = 100' Width = 48" Height = 24" Length = 100' P Lets add a prefabricated chamber: Skip to Chamber Model field Select Chamber Model = Acme 100A This sets size and layup length Storage Multiplier = 10 This sets the number of chambers! Set Invert = 100' 4-250 4-255
Pond Storage Options #5 Exploring the pond storage options Viewing Storage Results Examining the final pond storage P Lets add some more storage: < Custom stage-storage Select Surface Area method Enter desired stage-area data: 100' elevation -> 250 SF 101' elevation -> 350 SF Select any desired shape P Click OK to save all pond data P Open the pond report: < Double-click the pond < Explore the Summary report Note the detailed storage breakdown < Explore the Storage report Shows the overall pond storage P Close the report window 4-260 4-270 Embedded Storage Example #1a Defining complex storage arrangements Embedded Storage Example #1b Defining complex storage arrangements P Prepare another pond: < Create a new pond < Double-click to edit < Select Detention Pond < Select the Storage tab < Uncheck Large Units P Define the outer storage volume Create prismatoid storage volume Set invert at 100' Set size to 10'x20'x5' high Leave Side-Z=0 (for vertical sides) Set 50% voids for gravel fill Click OK to save outer storage definition 4-280 4-290
Embedded Storage Example #1c Defining complex storage arrangements PDefine the embedded perforated pipe Create a horizontal cylinder Set invert=100.5' Set Diameter=48" Set Length=40' Or set Length=20' & Storage Multiplier=2 Set Embed inside Volume 1 (the prismatoid) Leave Voids=100% (the pipe is empty!) Click OK to save pipe storage definition Embedded Storage Example #1d Examining the storage results P Click OK to save the pond data P Examine the pond report: < Double-click the pond < Explore the Summary report Note the embedded storage calculation < Explore the Storage report Note the inflection at the top/bottom of the pipe P Close the report window 4-300 4-310 Using Perforated Pipe *** End of Section *** Level Pool and exfiltration issues P Pond routing assumes that the water surface elevation is constant in all storage volumes. P Exfiltration is calculated at the outer storage surface, not at the perforations. < Exfiltration details in the next section! PAre there any other questions about pond storage? PFor detailed pond storage equations, please see the HydroCAD Owner s manual. PIf you performed the exercises, you may close HydroCAD at this time. < SAVE YOUR CHANGES when asked 4-320 4-330
Section 5 Pond Outlet Hydraulics
Section 5: Pond Outlets Defining and calculating pond outlet devices 85 Minutes Press Space, PageDown, or Click to advance. Press PageUp to reverse. Esc to exit. Right-Click for other options. Outlets Introduction What role do outlets play? P Outlet devices define the stage-discharge relationship for any pond P HydroCAD provides a range of outlet calculations... Copyright 2004 HydroCAD Software Solutions LLC All Rights Reserved - Duplication Prohibited 5-010 5-015 Pond Outlet Calculations Weir Calculations A wide range of built-in hydraulics solutions HydroCAD handles most types of weir flow Weir Custom Rectangular Weir V-Notch Weir Trap Weir Orifice Culvert H 1 H 2 Compound Weir Custom Weir/Orifice Submerged Weirs Let s review each of these groups... 5-020 Let s review each of these options... 5-030
Sharp-Crested Rectangular Weir What is the Crest Height? For most rectangular weirs P By default, a weir has no height limit < M=Infinity P HydroCAD 7.1 will implement a Weir Rise parameter M P When H>M, orifice flow occurs < Earlier versions must avoid weir overlap H L M Fine-tuning the basic weir equation P Crest height P = height of crest above approach channel P P is used to make slight adjustments to the C value to allow for approach velocity < Click Help for details < Or see manual H P 5-040 5-050 Broad-Crested Rectangular Weir V-Notch Weir Adjusting for the thickness of the spillway P Same equation as SCRW, but allows C to vary with head P Automatic C-value lookup for squareedged weirs < Values may also be entered manually < Special profiles listed in Owner s Manual Appendix D2 H L 5-060 Commonly used for low flows and flow measurements PTheta is total included angle, not from vertical PHydroCAD 7.1 will implement the weir rise parameter M < Uses orifice flow if H>M < Otherwise, M=Infinity 1 H M 5-070
Trapezoidal Weir Compound Weirs A combination of Vee and Rectangular weir flow Using the Weir Rise to avoid overlap P Theta is total included angle, just like v-notch P HydroCAD 7.1 will implement rise M < Otherwise weir has no height limit! 1 H L M P By default, all outlets are independent, and are added together P A compound weir (shown) will doublecount the overlap area P Setting the weir rise M 1 will switch to orifice flow and prevent overlap! M 2 M 1 5-080 5-090 Custom Weir/Orifice Used to model arbitrary weir and orifice shapes! Submerged Weirs What happens when tailwater is present? P Opening is defined by a stage-width table < Each segment is evaluated using trapezoidal weir or orifice flow P A single device table may define multiple openings, as shown here: P Normal weir equations assume free discharge P If tailwater exceeds weir crest, discharge is automatically reduced < See Owner s Manual for specific discharge equations H 1 H 2 5-100 5-110
Orifice & Culvert Flow Complete orifice & culvert calculations Rectangular Orifice - Vertical Plane For openings in the sides of a vertical riser or dam wall P Orifice flow when fully submerged H>M Rectangular Orifice Circular Orifice Horizontal or Vertical P Weir flow when partially submerged H<M Custom Weir/Orifice Low-Head Flow Culvert Flow Let s review each of these options... 5-120 P If tailwater is present < Weir flow occurs for area above TW < Constant-head orifice flow occurs for area below TW L H M 5-130 Rectangular Orifice - Horiz. Plane For the top of a riser or openings in the bottom of a vessel Circular Orifice - Vertical Plane For openings in the sides of a vertical riser or dam wall P Orifice flow is evaluated at all heads P Regular orifice flow occurs when h>r P Head is reduced for any tailwater P May also consider weir flow at low-heads < Details to follow H P Head is adjusted when partially submerged or for tailwater H h r 5-140 5-150
Circular Orifice - Horizontal Plane For the top of a riser or openings in the bottom of a vessel Orifices under Low-Head Automatically adjust for weir flow at low head POrifice flow is evaluated at all heads PHead is reduced for any tailwater PMay also consider weir flow at low-heads < Details to follow H P Vertical orifice equations always reduce to weir flow when partially submerged P Horizontal orifice (shown here) requires separate evaluation of weir flow < Done automatically when Weir Flow option is selected < Commonly used for an orifice at the top of a riser L 5-160 5-170 Modeling a Horizontal Grate A typical use for the discharge multiplier PTo model several identical devices: < Describe one device < Set the discharge multiplier for the number of devices! PRemember, all must be identical: < The openings in a vertical grate are at different elevations! x 4 = 5-180 Modeling Pipe & Culvert Flow What controls the flow through a pipe? Inlet P Depending on the inlet geometry, Manning s equation may not be the controlling factor. P A square-edged inlet (show above) has an entrance energy loss Ke = 0.5 which often causes inlet control. Outlet 5-190
Culvert Outlet Modeling Exfiltration Automatic evaluation of all flow controls Allowing for water lost into the ground P Complete culvert evaluation for each headwater/tailwater combination < Details in Owner s Manual P Automatic inlet/outlet control < More complete than a pipe reach, which considers only Manning s flow in barrel 5-200 P Exfiltration (infiltration) is usually modeled as a pond outlet device P The pond may be a drywell or other exfiltration area P Exfiltration flows are discarded to prevent further routing 5-210 Constant-Flow Exfiltration Constant-Velocity Exfiltration #1 When you have a pre-determined flow Exfiltration varies based on surface area PConstant exfiltration flow (CFS) occurs at all elevations < Flow is entered directly PCan set invert to prevent exfiltration through lower impervious area < No exfiltration occurs until water exceeds this level Invert Elevation 5-220 P Exfiltration velocity (FPM) applied to surface area P Assumes all flow is vertical (downward) If sides are vertical, flow occurs only through bottom P Can use invert to stop bottom exfiltration < For impervious bottom 5-230
Constant-Velocity Exfiltration #2 Exfiltration varies based on wetted area PExfiltration velocity (FPM) applied to wetted area PFlow occurs through all surfaces < Allows flow through vertical sides PUse invert to prevent bottom exfiltration 5-240 Constant-Velocity Exfiltration #3 Why not enter the perc rate? PHydroCAD exfiltration velocity is specified in feet-per-minute or inches-per-hour PCan convert perc-rate to velocity < But, can a large pond sustain the same exfiltration rate as a small test pit? 1 V Feet/Minute = (HydroCAD 6.0-7.0) 12 Perc Minutes/Inch V Inches/Hour = 60 Perc Minutes/Inch (HydroCAD 7.1 and up) 5-250 Exfiltration Comments Always use exfiltration with care! Modeling Compound Outlets Modeling these compound outlet devices is easy! P There are few standards for calculating exfiltration. P Exfiltration capability is likely to degrade over time. P Even the best exfiltration rates may not be a significant factor in peak-flow management. < Exfiltration must generally be used in conjunction with suitable detention storage. 5-255 P HydroCAD can model most any combination of outlet devices. P The key is in the device routing 5-260
Using the Outlet Device Routing P By default, each outlet device is routed directly to the primary discharge P This causes all flows to be added together Total Primary = 3 Device Outflow #1: Weir º Primary Device #2: Culvert º Primary Device #3: Orifice º Primary P There is no interaction between devices! P They are Independent Parallel Outlets 5-270 What about a Compound Outlet? A compound outlet involves device interaction P Simple rules for creating compound outlets: < Always start with the final device < Work upwards into the pond < Route each device as required < Check the stage-discharge curve 5-280 Riser Example #1a Riser Example #1b Modeling a riser outlet with side openings Adding a weir notch to the top of the riser P Follow these steps: < 1 Create the final culvert outlet Leave the routing to Primary < 2 Create the side opening(s) Set the routing to device #1 This routes flow to the culvert < 3 Create the top orifice Set the routing to device #1 Flow also goes to the culvert! 1 Primary 3 2 5-290 P Continuing from previous page: < 4 Create a weir Route flow to the culvert (device #1) < Beware of overlap with top opening Set weir rise (requires HydroCAD 7.1) Or model top opening #3 as a weir with reduced circumference Or model weir #4 as an orifice Primary 1 3 4 2 5-300
Riser Example #1c What about an emergency spillway? P Continuing from previous page: < 5 Create a separate weir Route the weir to the primary discharge Do NOT route to the culvert! (The flow doesn t go there) Could also route to secondary If the weir flow is being diverted 5 Primary 1 3 4 2 5-310 Automatic Flow Diversions Routing outlfow in two different directions P To divert an overflow weir: < Create a weir outlet < Set the weir routing to secondary A secondary outflow appears on the diagram! < Route the secondary outflow as required Just drag the outflow handle to the destination 4S 1P 3R 4R 5-320 Outlet Calculations #1a How is the discharge calculated? Outlet Calculations #1b Typical stage-discharge curve for weir flow 8 P First we ll examine some basic outlets < Weir flow < Orifice flow P What happens when we combine them? < Weir + Orifice flow (independent devices) < Weir routed to Orifice (series devices) 7 6 5 4 3 2 1 Flow starts at crest elevation 5-330 0 0 5 10 15 20 25 30 35 40 45 50 Discharge (cfs) 55 60 65 70 75 5-340
Outlet Calculations #1c Typical discharge curve for orifice flow 8 7 6 Outlet Calculations #1d Now combine (add) the weir and orifice flows 8 7 6 5 4 3 2 1 0 0 5 10 15 20 Also note inflection as orifice is fully submerged Flow starts at orifice invert 25 30 35 40 45 50 55 60 65 70 75 Discharge (cfs) 5-350 5 4 3 2 1 0 0 5 10 15 20 PWeir & orifice are both primary PTotal flow is sum of two devices 25 30 35 40 45 50 55 60 65 70 75 Discharge (cfs) 5-360 Outlet Calculations #1e Series devices: Route the weir into the orifice 8 7 6 5 4 3 2 1 0 0 5 PWeir flow is routed to orifice PFinal discharge is lesser of two devices < Discharge follows left-most curve 10 15 20 25 30 35 40 45 50 55 60 65 70 75 Discharge (cfs) 5-370 Software Exercises Exploring pond outlets in HydroCAD P Before we begin the software demonstration, are there any other questions about pond outlet calculations? P If you wish, you may perform the following exercises yourself, or just watch the demo. 5-380
Getting Started Prepare a pond to receive the outlet definitions P Get ready: < Start HydroCAD < Open the project Seminar1 Or create a new project if it doesn t exist P Prepare a pond to receive the outlet data: < Drag a pond from the palette < Edit the pond < Set the Catch Basin option < Select the Outlets tab Culvert Outlet #1 Let s create a basic culvert outlet P Define the culvert outlet: < On the outlet table, double-click the first blank line < Select Culvert and click OK < Set the culvert parameters: Invert=100', length=20', S=0.01 n=0.013, diameter=24" Select CMP, square edge headwall (Ke=0.5) Leave Routing at Primary Click OK to save the culvert data P Continue to next page... 5-390 5-400 Culvert Outlet #2 Examining the outlet calculations P To extend the discharge graph: < Select the Advanced tab < Set Flood Elevation = 108' P Click OK to save pond data P Open the pond report: < Double-click the pond < Explore the Summary report < Explore the Discharge plot P (Leave the report open...) 5-410 Riser Example Let s add a riser to the culvert barrel P Modify the same pond: < Click the Edit button on the report window < Select the Outlets tab < Create a circular orifice for the top of the riser: Create an orifice (double-click the next blank line) Set Invert=105', Diameter=48", Horizontal Set Routing = Device 1 (Route to the culvert!) < Click OK (twice) to save the description P Report is automatically updated! < Examine the Stage-Discharge plot Note orifice flow starts at 105' Culvert flow resumes at 106' 5-420
Low-Flow Orifice Add a multiple orifice in the side of the riser P Modify the same pond: < Click Edit button on the report window < Select the Outlets tab Double-click a blank line Define a 3" vertical orifice with Invert=102' For a multiple opening, set Discharge Multiplier=4 Set Routing = Device 1 (the culvert) < Click OK (twice) to save the description P Report is automatically updated! < Examine the Stage-Discharge plot Note side orifice flow at 102' Emergency Spillway Create a weir to be routed separately PModify the existing pond: < Click Edit button on the report window < Select the Outlets tab < Create a Broad-Crested Rectangular Weir Invert=107', Length=10', Breadth=2' Set Routing = Secondary < Click OK twice to save the pond 5-430 5-440 Spillway Results Let s examine the reports PWhen we clicked OK, reports are automatically updated PExamine the Stage-Discharge plot Note secondary discharge curve (red) Total discharge also shown (grey) Right-click to select curves Setting a Fixed Tailwater HydroCAD provides several options for tailwater handling P Modify the existing pond: < Click Edit button on the report window < Select the Tailwater tab < Select Fixed Elevation for the Primary Tailwater < Enter an elevation of 103' < Click OK to save the description P Report is automatically updated < Examine the Stage-Discharge plot Note no discharge below 103' 5-445 5-450
Vee/Trapezoidal Weir Lets explore the other outlet devices P Vee/trapezoidal weir < Invert Elevation - used for all devices < Notch Angle (total included angle) < Weir Coefficient (set automatically) < Crest Length (zero for V-notch) < Weir Rise (added in HydroCAD 7.1) P Remember to use HELP button Rectangular Weir Lets explore the other outlet devices P Sharp-crested rectangular weir < Invert Elevation < Crest Length < End Contractions (0-2) < Crest Height (above approach channel) < Weir Rise (added in HydroCAD 7.1) P Can also use broad-crested weir < But SC is usually sufficient 5-460 5-470 Special Outlet Lets explore the other outlet devices P Special outlet < Accepts user-defined rating table < Discharge vs Elevation -or- Discharge vs Head < Can extrapolate when table is exceeded P Reminder: < Right-click any table for special options Exfiltration Outlet Lets explore the other outlet devices P Exfiltration < Can set exfiltration Flow -or- Velocity < Velocity can be applied to: Surface Area (flow horizontal surfaces only) Wetted Area (flow through all areas, vert & horiz) Horizontal Area < Invert can be used to exclude impervious areas < Can use Special outlet for custom curves 5-480 5-490
*** End of Section *** PAre there any other questions about pond outlet devices? P For detailed outlet equations, please see the HydroCAD Owner s manual. P If you performed these exercises, you may close HydroCAD at this time. < SAVE YOUR CHANGES when asked 5-500
Section 6 Pond Routing
Section 6: Pond Routing Transforming an inflow hydrograph into an outflow hydrograph 35 Minutes Routing Introduction What is a pond routing? PWhat role does a pond play in the model? PHow is the inflow hydrograph altered by the pond routing? Press Space, PageDown, or Click to advance. Press PageUp to reverse. Esc to exit. Right-Click for other options. Copyright 2004 HydroCAD Software Solutions LLC All Rights Reserved - Duplication Prohibited 6-010 6-015 Pond Routing Effects #1 How is the inflow hydrograph altered by the routing? Peak occurs later (time lag) Peak flow is reduced (attenuation) Pond Routing Effects #2 How much water is stored in the pond? PMaximum storage occurs at peak outflow < Volume is equal to area between curves PPond is at equilibrium < Q OUT = Q IN T i m e 6-020 T i m e 6-030
Estimated Pond Sizing How much storage do I need to attenuate the peak to the target level? PAfter you perform a pond routing, you know the actual peak outflow and storage used. < But how do you estimate the required storage in advance? PThe pond sizing report will tell you the approximate storage required to attenuate your actual inflow to any desired level < First, create a pond with the actual inflow Pond data is optional < Then open the sizing report... 6-040 Using the Pond Sizing Report How much storage do I need? P Find your target outflow on the left axis P Move right to the curve and down to the bottom axis P This is the approximate required storage! Required Storage (AF) 6-050 Pond Sizing Notes How much storage do I need? P The pond sizing report provides an initial estimate only < Use this to design a trial pond and then refine the design P The sizing report is based on the actual inflow and an assumed discharge curve < Your sizing may vary depending on your exact outlet configuration Other Detention Effects #1 What happens to the larger watershed? P Existing peaks may occur at different times P This avoids direct peak addition and minimizes downstream flooding 7 Existing Combined Flow 7 Adjacent Watershed 7 Existing Site 6-060 T i m e 6-070
Secondary Detention Effects #2 What happens to the larger watershed? PDeveloped discharge may have same peak PBut peak widening increases total flows and contributes to downstream flooding Developed Combined Flow 7 (peak has increased) Developed Site 7 (same peak) Trends in Stormwater Management Sometimes smaller is better P Manage stormwater near the source < Distribute mitigation measures throughout the site < Minimize use of large-scale ponds < Utilize all detention opportunites < Maximize inflitration P Integrate site design and stormwater management T i m e 6-080 6-085 Starting Elevation Allows for a pre-storm water level in a pond P By default, all ponds start empty P Starting Elevation sets pre-storm water level < If above outlet, will cause immediate outflow < Can be used without inflow hydrograph to observe draw-down of pre-charged pond Base Flow Calculations Base flow can be used to model constant pre-runoff flows P Base flow is added to inflow hydrograph < Base-flow is included in all downstream flows P Automatic base flow option calculates flow required to maintain starting elevation < Keeps the pond at equilibrium < Prevents draw-down from starting elevation < Useful for ponds with pre-storm flows 6-090 6-100
Detention Time How long is the water stored in the pond? P Detention time is the average length of time that a molecule of water stays in the pond < This is not a routing procedure - It is an analysis that is performed after the routing is complete P There are several ways to calculate T DET P HydroCAD provides two procedures: < Center-of-Mass method < Plug-Flow method P Lets see how these are calculated... 6-110 Center-of-Mass Detention Time #1 A basic procedure for calculating detention time P First, calculate the center-of-mass time for the inflow hydrograph T i m e 6-120 Center-of-Mass Detention Time #2 A basic procedure for calculating detention time PThen calculate the center-of-mass time for the outflow hydrograph Center-of-Mass Detention Time #3 A basic procedure for calculating detention time P The detention time is the difference between the inflow and outflow center-of-mass times T i m e 6-130 T i m e 6-140
Center-of-Mass Detention Time #4 P Advantages: < Simple, graphical solution < Fairly easy to verify results by hand P Limitations: < Reduces each hydrograph to a single time value Doesn t consider overall hydrograph shape < Can be fooled by certain hydrographs < Not a physical evaluation of the flow PA better alternative: < The Plug-Flow method... 6-150 Plug-Flow Detention Time #1 A better detention time procedure P First, divide the outflow into plugs of equal volume T i m e 6-160 Plug-Flow Detention Time #2 P Next, identify when the first plug enters the pond < Inflow and outflow plugs have equal volume, but different duration. Plug-Flow Detention Time #3 P Now calculate the time between the plugs < This is the detention time for a single plug T i m e 6-170 T i m e 6-180
Plug-Flow Detention Time #4 PRepeat the process for all the plugs, calculating the average of all the detention times < The average gives the overall detention time for the entire event T i m e 6-190 Plug-Flow Comments P Advantages: < Calculation is based by physical situation < Sensitive to exact hydrograph shape < Works with complex situations such as wet ponds PThings to understand: < Produces a best case (maximum detention time) based on a first-in first-out scenario. < Any pre-storm water is displaced before any of the new runoff leaves the pond. Wet ponds have a greater plug-flow detention time! Center-of-mass method ignores any pre-filled storage P HydroCAD provides BOTH techniques 6-200 Other Water Quality Requirements Using HydroCAD to meet your local regulations P Detain the first inch for 24-hours < Exactly what does this mean? < Read your regulations very carefully! PTo verify compliance you can use: < Tabular inflow-outflow hydrograph Shows the pond volume at each time step Software Exercises Exploring these topics in HydroCAD P Before we begin the software demonstration, are there any other questions about pond routing calculations? P If you wish, you may perform the following exercises yourself, or just watch the demo. 6-210 6-220
Lets examine a pond routing To save time, we ll work with an existing project P Getting ready < Start HydroCAD < Open the Mountain View Housing Complex P Examine the routing < Double-click pond 3P < Examine the summary report Note the detention time calculations In this case PF and CM results are very close Click any line for details (HydroCAD 7.1) < Examine the hydrograph Note the storage volume Using the pond sizing report Estimating the required storage PExamine the sizing report < Make sure the report is open for pond 3P < Click the Sizing tab Try the 2D view Select Table format To see more values, remove the Shrink option Click Help for detailed instructions 6-230 6-240 Modeling a wet pond How do we handle the initial water level in the pond? P Use the options on the Advanced tab: < Set the Starting Elevation: Set a Starting Elevation of 20.5' and click OK Note immediate outflow at start of hydrograph But the outflow (and elevation) are dropping! < Continue to next slide... Pre-Storm Flows What if the pond is discharging before the storm begins? PUse the options on the Advanced tab: < Add a base flow: Set a Base Flow of 1 CFS and click OK Note initial decline is reduced but not eliminated < Try Automatic Base Flow: Select Automatic Base Flow and click OK Pond is now at equilibrium! Exact base flow is shown on Summary 6-250 6-260
*** End of Section *** P Are there any other questions about pond routing calculations? P For specific routing equations, please see the HydroCAD Owner s manual. P If you performed the exercises, you may close HydroCAD at this time. < You do NOT need to save your changes. P ** Take a 10-minute break ** < Please complete your evaluations! 6-270
Section 7 Routing Methods
Section 7: Routing Methods Hydrograph Routing Alternatives 30 Minutes Press Space, PageDown, or Click to advance. Press PageUp to reverse. Esc to exit. Right-Click for other options. Copyright 2004 HydroCAD Software Solutions LLC All Rights Reserved - Duplication Prohibited 7-010 Pond Routing Methods PHydroCAD provides several routing methods for different situations: < Storage-Indication (SI) The default - Use it whenever possible < Dynamic Storage-Indication (DSI) When variable tailwater is a factor < Simultaneous Routing (Sim-Route) For loop flows and reversing flows (use sparingly) PLet s examine each method in more detail... 7-020 Storage-Indication Method The most widely-used pond routing procedure P Features < Very fast and stable < Widely used (by TR-20 and many others) P Limitations < Evaluates one node at a time < Cannot see downstream < Requires static rating curve (i.e. fixed tailwater) P Comments < HydroCAD will generate a (tailwater) warning if a different routing method is needed < Otherwise, stick with storage-indication! 7-030 Dynamic Storage- Indication Method An adaptation of the traditional SI method P Features < Same as storage-indication, but re-evaluates outlets devices at each time step < Allows ponds to respond to varying tailwater P Limitations < Takes longer to calculate (but still quite fast) < Not as stable as SI P Comments < Recommended procedure for variable tailwater < But stick with SI unless you get a tailwater warning 7-040
Routing Oscillations Understanding and correcting routing problems P Oscillations can occur during routing < Excess fluctuations in the outflow P Always check hydrographs by eye < Do they look reasonable? P Oscillation warning messages < Click on message for details < Adjust finer routing -or- < Use smaller time increment Simultaneous Routing Recommended only for specific applications! P Features < Re-evaluates outlets at each time step, like DSI Allows ponds to respond to varying tailwater < Doesn t require a fixed flow order Loop flows and reverse outlets are OK P Limitations < Takes longer to calculate < Less stable than SI or DSI P Comments < Recommended only for loop or reverse flows < Stick with SI or DSI if at all possible 7-050 7-060 Modeling an Open Channel It depends on the situation - and your design objectives P 1) Flow segment within a subcatchment < Recommended for channels with inflow along their length and without a separate inflow hydrograph P 2) Separate reach routing < When inflow hydrograph routing is required < Generally used only for long channels Short channels may not alter the overall model But when peak timing is critical, reach delays can have a significant effect on the model P Note: Many models will have no reaches! 7-070 How to model a Pipe It depends on the situation P 1) Flow segment within a subcatchment < If the pipe is within an area that is being modeled as a single subcatchment P 2) Separate reach routing < ONLY for open channel flow without inlet control < Sometimes used to simulate storm sewer outflow Produces a flat-topped hydrograph with correct volume P 3) Culvert outlet on a pond < Recommended for most situations < Can route one pond directly to the next 7-080
Estimating a Storm Sewer Outflow Estimating a Storm Sewer Outflow PAny pond analysis requires a complete inflow hydrograph - not just the peak flow PThis can sometimes be simulated with a subcatchment and a single pipe reach < Produces a flat-topped hydrograph with correct volume < Can be calibrated to specified peak flow Outflow PPeak is reduced to pipe capacity PCorrect inflow volume is retained 7-090 T i m e 7-095 Reach Options A reach performs a hydrograph routing through an open channel based on normal Manning s flow P Section options < Circular pipe, rect/vee/trap, parabolic < Custom stage-discharge or wetted perimeter P Reach profile P Tailwater options (always free discharge) P Advanced options Warning Messages Please - Read and understand all warning messages! P Click on any warning message for details P Some warnings may be OK < You must review & understand each message P Warnings normally appear on printed reports < But may be suppressed if desired 7-100 7-110
Reach Routing Effects *** End of Section *** How is the inflow transformed by the reach? Attenuation and lag due to storage routing (SI) Additional lag can be added for travel time (SI+Translation) P Are there any other questions about routing procedures? P For detailed routing equations, please see the HydroCAD Owner s manual. P Also see articles on the Support page at www.hydrocad.net T i m e 7-120 (There are no exercises in this section) 7-130
Section 8 Links
Section 8: Links For specialized hydrograph operations 20 Minutes Press Space, PageDown, or Click to advance. Press PageUp to reverse. Esc to exit. Right-Click for other options. Copyright 2004 HydroCAD Software Solutions LLC All Rights Reserved - Duplication Prohibited 8-010 General Link Capabilities A link can be used for a number of special purposes P Sum on-screen inflows < Can also be done with undescribed reach or pond P Manual hydrograph entry < If you have a known hydrograph P Automatic hydrograph import < Usually from another project < Now supports multiple storm events < Also imports other files (see next slide) 8-020 Sample Hydrograph File For hydrograph import and linking projects FileUnits=English [hydrograph] Name=Outflow 1 t0=5*3600 dt=.5*3600 Flow=0 0.2 0.6 1.2 2.5 4 Flow=6 9 10 10 9.5 8 6.5 [hydrograph]...more... English or Metric Start time & time step Unlimited flow values Multiple hydrographs or events per file 8-030 Advanced Link Options Options for additional hydrograph processing PFlow threshold < Subtracts all flow below the threshold PFlow limit < Removes any flow above the limit PDischarge multiplier < Adjusts all flows by a given factor PTime multiplier < Changes the hydrograph time scale 8-040
Link Elevation options A link can also be used to define a tailwater elevation P Defining a water surface elevation < Fixed elevation < Tidal elevation Set high/low tide elevations Set time of high tide P Used with tailwater-sensitive routing procedures Software Exercises Exploring links in HydroCAD P Before we begin the software demonstration, are there any other questions about link calculations? P If you wish, you may perform the following exercises yourself, or just watch the demo. P (Exercises are optional) < Skip if time is short 8-050 8-060 Explore an existing link For special hydrograph operations P Getting ready < Start HydroCAD < Open the Mountain View Housing Complex P Explore the link < Double-click link 1L < Examine the hydrograph Note split due to flow threshold < Examine the summary Note the manual hydrograph table Editing a link For special hydrograph operations P Edit the link and explore each tab: < Manual tab Used for direct hydrograph entry < Advanced tab For special hydrograph processing < Elevation tab For setting a fixed or tidal elevation 8-070 8-080
*** End of Section *** PAre there any other questions about link calculations? P For detailed routing, please see the HydroCAD Owner s manual. PIf you performed the exercises, you may close HydroCAD at this time. < Do NOT save your changes. 8-090
Section 9 Printing and Data Management
Section 9: Printing & Data Management Preparing reports and managing your data 25 Minutes Press Space, PageDown, or Click to advance. Press PageUp to reverse. Esc to exit. Right-Click for other options. Copyright 2004 HydroCAD Software Solutions LLC All Rights Reserved - Duplication Prohibited Printing & Exporting: One node at a time Reports can be printed individually during design work P Open the desired report and click Print < Prints immediately to default printer < Use Print Page Settings to change layout P Can also Export to these formats: < TXT - for editing < CSV - for spreadsheets of database < EMF, BMP, JPEG - for images 9-010 9-020 Multi-Page Reports Just pick the options and go! PSelect Print Report, or click the Printer icon PNow includes multiple rainfall events < Just select the event(s) to be printed PWide range of report options < Node summary < Hydrographs < Stage-discharge data < Routing diagram < Etc. Printing the Routing Diagram P Select Print Diagram < or use the button on the tool bar P To export to EMF, BMP or JPEG, select Print Diagram-to-file 9-030 9-040
Using other formats For sending complete reports P PDF format < Great for sending finished reports < Requires a PDF printer driver P MS Word format < Can be produced with special driver < But files are VERY large < Other formats are generally better Automatic Data Export Transfer project data to other programs P Data is automatically exported when project is saved and closed < Configured on Settings Export screen P Hydrograph export < Inflow, outflow, and/or unrouted hydrographs P CSV Spreadsheet data < Node tables and/or hydrograph tables P Automatic export for all rainfall events! 9-050 9-060 CAD Integration Linking HydroCAD to your site plan P HydroCAD provides an open standard for data exchange P Subcatchment boundaries, CN values, and other data can be defined as AutoCAD layers and exported to HydroCAD P For the latest news on data exchange capabilities please visit www.hydrocad.net Units of Measure Use English, metric, or custom units on any project P Each project can use English or Metric < Select units on Settings Units screen < Input/output can use different units! P Reports update automatically for new units < Open a report window and try it! P Can also create custom units definition < See English and Metric definition printouts 9-070 9-080
File Management Tips #1 Tips for managing your HydroCAD files P Where are your projects stored? < Search for all *.HCP files P Each project is stored in a single.hcp file < See sample HCP file in your hand-outs P Right-click a HCP file to edit manually < Keep a backup and edit with care! < See printed example File Management Tips #2 Tips for managing your HydroCAD files P Many ways to open a project file < Use Project Open in HydroCAD < Launch the file from Windows < From the Windows Documents menu < From a command line P Can use most Windows file operations directly on HCP files < Copy or move files < Backup and restore 9-090 9-100 Sending HydroCAD Projects by Email Tips for managing your HydroCAD files P Sending projects by email < Just attach the HCP file to any message < Make sure the file is closed! P Receiving a project by email < Can open the attachment directly < Or extract the file and store it first < Anyone can open a project with the free Sampler Default Projects Avoid re-entry of common settings for each new project P To set your own defaults: < Create a new project called Default < Adjust project settings as desired Rainfall and units are commonly customized Other settings can be changed as well < Save the Default project P New projects will automatically inherit your default settings! < Each folder can have its own default settings < Or put global defaults in HydroCAD folder 9-110 9-120
Combining Projects *** End of Section *** Using the full capacity of your program P Use Project Add to combine projects < After you upgrade to a larger program < Avoids need for a link < Set unique node numbers before adding P Are there any other questions about printing and data management? (There are no exercises in this section) 9-130 9-140