What would be the perfect format for a Water Related Engineering Blog?

What would be the perfect format for a Water Related Engineering Blog?

A note for my readers.  I am having an internal public discussion with myself.  If you have other ideas or suggestions please email me.  I get a lot of emails and very little non spam comments on my blogs. It is probably a characteristic of engineers who work for a living. 

What would be the best or perfect format for a  Water Blog?

1. A general introduction to why the blog matters to the reader and what will either be explained or demonstrated in the blog.
2. An introduction to the feature discussed in the blog.
3. An equation or psuedo code to illustrate the fundamentals of the item discussed in the blog,
4. A few images showing how the feature discussed is used in the Water related Software.
5. Sensitivity Analysis for the feature or a least a mention of how sensitive the parameter of feature is in the model
6. Drawbacks of the feature, or known workarounds.
7. Related Blogs and URL's
8. Summary of what was discussed.

Here are other blog making ideas

http://www.successfulblogging.com/16-rules-of-blog-writing-which-ones-are-you-breaking/
Here is a long snippet from the above mentioned post

16 Rules of Blog Writing and Layout

1. Format every blog post Careful formatting will make your blog posts easier for people to scan. Write your posts with the page layout in mind or edit them to make sure they’re well formatted for scan reading.

2. Constrain column width Keep the blog post column width about 80 characters or less (including spaces) and your readers will thank you for it. Check out these before and after screen shots of Under the Mango Tree. I advised Stacyann to update her blog to make it easier to read and changing the column width for the main body of text was one of the first things we sorted out. Wide columns of text are an instant turn off and very hard to read. The difference is incredible and it’s such a simple change.

3. Use Headers and Sub-headers Headers and sub-headers will break up long blog posts, help people scan read your blog and convince them to read the post. Read How to Write Hypnotic Headlines to read more about the importance of headlines and headers for blog writing.

4. Use lists Numbered lists or bullet pointed lists help people scan blog posts fast and find the information they’re looking for quickly.

5. Use punctuation Use full stops, commas, dashes and colons to break up each paragraph into smaller pieces of information that make sense quickly. No one wants to read the same sentence several times to try to make sense of it. If you’re not confident about punctuation keep sentences short. As you practice writing and start to improve you can experiment and lengthen your sentences, chucking in a long one here and there to keep things interesting for readers, and make sure they’re really paying attention. Long sentences are fine but check that every sentence makes sense and the meaning is clear.

6. Short paragraphs Because reading is harder online it’s best to break text into manageable chunks. Paragraphs should be much shorter online than on paper with two to six sentences per paragraph a good guideline for blog posts.

7. Font type Sans-serif fonts (without the squiggly bits) are generally supposed to be easier to read on-screen, in particular Verdana. Successful Blogging uses the sans-serif font Roboto (without the squiggly bits) which is also designed for easy reading on-screen.

8. Font size Big is better. Teeny tiny writing is hard to read online, even for people with 20/20 vision like me. Make it bigger. Check out some of your favorite blogs, compare the font size they use and decide what works best for your readers. If they’re older they might prefer even bigger text than the average blog reader.

9. Be bold Don’t overuse bold text or it loses its effectiveness but do use bold text to make a splash and highlight important sentences that will catch people’s attention and draw them into, or on with, the blog post. 

10. Drop the italics Italics are hard to read in print. Couple that with on-screen reading already being challenging and banish italics from your blog writing. I hate them. If you can avoid italics please do.

11. Capital letters Use capitals for proper nouns and at the beginning of sentences but avoid writing all in capitals because it’s harder to read. PLUS USING CAPITAL LETTERS CONSTANT IS THE ONLINE EQUIVALENT OF BEING SHOUTED AT. Sorry, just wanted to get the point across.

12. White space

Readers need somewhere to rest the eye and a good blog layout leaves plenty of blank space.

CLICK TO TWEET

Make sure your blog isn’t too busy or distracting and gives readers somewhere to rest their eye from time to time.

13. Background color Most blogs and websites get the contrast between text color and background color right, but make sure your blog background doesn’t make the text hard to read. It makes me sad that a white background with black text has become the default for most blogs. Bright yellow text on a black background is easiest to read but that’s a confrontational look. Dark text on a light background has a wider appeal but consider using another light color for the background as white gives off a harsh glare. There are plenty of choices which look good and are still easy to read but without the glare of white: try light grey, minty green or pale yellow.

14. Use images

Good use of images will draw readers in to your blog posts. Sometimes I read a post purely because I like the image. Ideally your images will add to your blog or emphasize your message. Even if they can’t do that use them to break up text, draw your reader’s eye down the page and reward them for reading and spending time on your blog. Some blogs likeViperchill turn their headers and sub-headers into images which makes the text look more attractive and helps people scan read.

15. Be consistent  You don’t know how readers found your blog. You can’t be sure if they arrived straight at your latest post, on your about page or via an archived post. You can’t know which order people will read your blog in so every post you write needs to tell the same story about you, your message, your blog and your values.

16. Tell a story Speaking of stories, every blog post needs to have a beginning, a middle and an end. Think of it as an introduction, the main information and conclusion if you prefer. Even if you don’t give use those sub-headings because, hopefully, you’ve come up with hotter ones, do follow the convention to avoid confusing your readers.

RDII Components at a node for a 100 year simulation in SWMM 5

Introduction:  This set of blogs uses the 1000 year rainfall/runoff/hydraulics model that you can download at http://swmm2000.com/forum/topics/1000-year-simulation-with-rainfall-in-swmm-5 to show the inner workings of SWMM 5 and by extension InfoSWMM and H2oMap SWMM using a QA/QC version of SWMM 5 with extended graphics.   I always hope that seeing the inner workings of a SWMM 5 feature helps to understand the code, sensitivity and importance of a parameter.   It also helps show sometimes when a parameter is not important.   In this example, we show some of the internal working of the RDII estimation for SWMM5. 

Discussion:  There are nine main parameters for estimating RDII in SWMM 5:

1.       Slow response or R1, T1 and K1
2.      Medium response  R2, T2 and K2
3.      Fast Response or R3, T3 and K3
4.      The RDII flow is associated with a Node in SWMM 5 (Figure 1)
5.      The RDII flow is composed of three separate time series generated from the slow, medium and fast R,  T and K values (Figure 2)
6.      If you look at the total number of RDII events for the 100 years, the number of events goes down based on the value of the Time Base of the UH or T*K (also Figure 2) 

Figure 1.   RDII at a node for a 100 year simulation in SWMM 5

  

Figure 2.   RDII Component Events over the 100 year period using the SWMM 5 statistics block

The total losses include both evaporation and infiltration for a 100 Year SWMM 5 Simulation

Introduction:  This set of blogs uses the 1000 year rainfall/runoff/hydraulics model that you can download at http://swmm2000.com/forum/topics/1000-year-simulation-with-rainfall-in-swmm-5 to show the inner workings of SWMM 5 and by extension InfoSWMM and H2oMap SWMM using a QA/QC version of SWMM 5 with extended graphics.   I always hope that seeing the inner workings of a SWMM 5 feature helps to understand the code, sensitivity and importance of a parameter.   It also helps show sometimes when a parameter is not important.   In this example, the components of the total losses in SWMM 5 which are the infiltration from the pervious area and the evaporation from the impervious and pervious area are shown (Figure 1)

Discussion:  The total losses (Figure 1) are:

1.       The infiltration only losses from the pervious area,
2.      Evaporation losses from the pervious and impervious area weighted by areal coverage
3.      The total losses which are the sum of the evaporation plus infiltration losses

a.      In a continuous simulation the times of infiltration only loss is less than the total losses due to the times when evaporation only is occurring from the depression storage of the Subcatchment

b.       The Statistics assume an inter-event time of 0 hours to capture all of the one hour saved time increments

Figure 1.   The total losses include both evaporation and infiltration for a 100 Year SWMM 5 Simulation

Green Ampt Infiltration for the Storage Nodes of SWMM 5

Introduction:  This set of blogs uses the 1000 year rainfall/runoff/hydraulics model that you can download at http://swmm2000.com/forum/topics/1000-year-simulation-with-rainfall-in-swmm-5 to show the inner workings of SWMM 5 and by extension InfoSWMM and H2oMap SWMM using a QA/QC version of SWMM 5 with extended graphics.   I always hope that seeing the inner workings of a SWMM 5 feature helps to understand the code, sensitivity and importance of a parameter.   It also helps show sometimes when a parameter is not important.   Continuing with the recent blogs on Green Ampt Infiltration, you can also simulate the infiltration and evaporation from a Storage node in SWMM 5

Discussion:  The infiltration and evaporation can be simulated in SWMM 5 using Green Ampt Infiltration:

1.       The three Green Ampt parameters are entered in the Storage Node Dialog
2.      The statistics for the whole run are shown in the Storage Node Summary Table for Volume, Percent Full and Percent Loss
3.      The Node Storage Graph for Infiltration varies with the time and the depth of the storage nodes along with the side area (based on the average depth over a time step) and the bottom area of the node.   In figure 2, Area0 is the bottom area and Area1 is the side area.

Figure 1.   Green Ampt Infiltration for the Storage Nodes of SWMM 5 for a 100 year Simulation

Figure 2.  The bottom and side area of a storage pond (Functional)

The Internal Green Ampt Parameters, Soil Moisture and IMD for a 100 Year SWMM 5 Simulation for Green Ampt Infiltration

Introduction:  This set of blogs uses the 1000 year rainfall/runoff/hydraulics model that you can download at http://swmm2000.com/forum/topics/1000-year-simulation-with-rainfall-in-swmm-5 to show the inner workings of SWMM 5 and by extension InfoSWMM and H2oMap SWMM using a QA/QC version of SWMM 5 with extended graphics.   I always hope that seeing the inner workings of a SWMM 5 feature helps to understand the code, sensitivity and importance of a parameter.   It also helps show sometimes when a parameter is not important.   In this example, we show some of the internal working of the Green Ampt Infiltration Parameters over the 100 year period. 

Discussion:  Key internal parameters for Green Ampt infiltration are

FUMax is the Saturated Moisture Content of the Upper Zone (internal units of feet)

F or FTOT in the graph is the Cumulative event infiltration at start of time interval (internal units of feet)

FU is the current moisture content of upper zone (internal units of feet)

As shown in Figure 1,  IMD and Soil Moisture are related.  When the soil moisture is zero then the IMD is equal to the maximum values of IMD or IMDMax.

These three parameters are used to calculate the IMD during the simulation among other important uses

IMD =  [ Maximum Allowable Infiltration – Current Moisture Content of the Upper Zone ] / Depth of the Upper Soil Layer

Or  IMD = [ FUMax – FU ] / Depth of the Upper Soil Layer

Soil Moisture = IMDMax - IMD 

Figure 1.   The Internal Green Ampt Parameters, Soil Moisture and IMD for a 100 Year SWMM 5 Simulation for Green Ampt Infiltration

The Internal Green Ampt Parameters, FUMax, FU and FTOT or F for a 100 Year SWMM 5 Simulation for Green Ampt Infiltration

Introduction:  This set of blogs uses the 1000 year rainfall/runoff/hydraulics model that you can download at http://swmm2000.com/forum/topics/1000-year-simulation-with-rainfall-in-swmm-5 to show the inner workings of SWMM 5 and by extension InfoSWMM and H2oMap SWMM using a QA/QC version of SWMM 5 with extended graphics.   I always hope that seeing the inner workings of a SWMM 5 feature helps to understand the code, sensitivity and importance of a parameter.   It also helps show sometimes when a parameter is not important.   In this example, we show some of the internal working of the Green Ampt Infiltration Parameters over the 100 year period. 

Discussion:  Key internal parameters for Green Ampt infiltration are

FUMax is the Saturated Moisture Content of the Upper Zone (internal units of feet)

F or FTOT in the graph is the Cumulative event infiltration at start of time interval (internal units of feet)

FU is the current moisture content of upper zone (internal units of feet)

As shown in Figure 1, FUMax is constant during the simulation, whereas F and FU vary during the Simulation.  These three parameters are used to calculate the IMD during the simulation among other important uses

IMD =  [ Maximum Allowable Infiltration – Current Moisture Content of the Upper Zone ] / Depth of the Upper Soil Layer

Or    IMD = [ FUMax – FU ] / Depth of the Upper Soil Layer

FUMax =  Depth of the Upper Soil Layer * IMDMax

Figure 1. The Internal Green Ampt Parameters, FUMax, FU and FTOT or

F for a 100 Year SWMM 5 Simulation for Green Ampt Infiltration

Initial Moisture Deficit or IMD for a 100 Year SWMM 5 Simulation for Green Ampt Infiltration

Introduction:  This set of blogs uses the 1000 year rainfall/runoff/hydraulics model that you can download at http://swmm2000.com/forum/topics/1000-year-simulation-with-rainfall-in-swmm-5 to show the inner workings of SWMM 5 and by extension InfoSWMM and H2oMap SWMM using a QA/QC version of SWMM 5 with extended graphics.   I always hope that seeing the inner workings of a SWMM 5 feature helps to understand the code, sensitivity and importance of a parameter.   It also helps show sometimes when a parameter is not important.   In this example, we show some of the internal working of the Green Ampt Infiltration Parameters over the 100 year period.  The IMD is normally near the initial user defined value but it can go to zero during the course of the simulation (Figure 1)

Discussion:  A key internal and user defined parameter is the Green Ampt Infiltration parameter Initial Moisture Deficit.  It starts out at the user Initial Deficit and then is computed at each hydrology time step using the equation

IMD =  [ Maximum Allowable Infiltration – Current Moisture Content of the Upper Zone ] / Depth of the Upper Soil Layer

Figure 1.   Initial Moisture Deficit or IMD for a 100 Year SWMM 5 Simulation for Green Ampt Infiltration

Rainfall and Losses One Watershed for a 100 Year Simulation with SWMM 5 Statistics at a saved time step of one hour.

Introduction:  This set of blogs uses the 1000 year rainfall/runoff/hydraulics model that you can download at http://swmm2000.com/forum/topics/1000-year-simulation-with-rainfall-in-swmm-5 to show the inner workings of SWMM 5 and by extension InfoSWMM and H2oMap SWMM using a QA/QC version of SWMM 5 with extended graphics.   I always hope that seeing the inner workings of a SWMM 5 feature helps to understand the code, sensitivity and importance of a parameter.   It also helps show sometimes when a parameter is not important.   In this example, we show how the statistics change when you change the reporting time step.  You can only see what you report, if you only save every hour or 15 minutes then you may miss some important model results.

Discussion:  In this blog we look at the Rainfall and Pervious Losses for the 100 year period:

Generally, it is better to have finer time steps for rainfall and for reporting.    As you can see in Figure 1 we only get pervious runoff when the rainfall is greater than the infiltration rate which explains the findings of this blog http://www.swmm5.net/2013/12/runoff-from-one-watershed-for-100-year.html  in which the pervious flow is small an infrequent.  The pervious area runoff is a function not only of the pervious infiltration parameters but the rainfall time interval. 

Embark on a hydrological odyssey spanning a millennium with this series of blogs, anchored by the extensive 1000-year rainfall/runoff/hydraulics model available at SWMM2000. Utilizing a specialized QA/QC version of SWMM 5 that boasts enhanced graphics, these insights aim to illuminate the intricate mechanics of SWMM 5, as well as its counterparts InfoSWMM and H2oMap SWMM. 🌧️🔄🛠️

The quest for understanding isn't just academic; it's a practical exploration into how pivotal parameters influence the model's behavior, highlighting their significance or, occasionally, their redundancy. 📊🧐

Key Insight: The essence of this narrative lies in the influence of reporting time steps on statistical output. The granularity of data — whether recorded every hour or every quarter of an hour — can dramatically shape the story your model tells. Miss a beat, and you could miss a flood. ⏱️💧

Focal Point: This particular chapter delves into the interplay between rainfall and pervious surface losses over a century-long saga. The model suggests a critical truth: the finer the temporal resolution of rainfall and reporting, the sharper the picture of runoff. As demonstrated in Figure 1 and supported by SWMM5.net, pervious runoff is a rare and minimal occurrence, emerging only when rainfall intensity surpasses the rate of infiltration. This revelation underscores the delicate dance between rainfall intervals and pervious surface parameters. 🌳💦📈

Stay tuned to this blog series for more revelations from the vast timescales of hydrological phenomena, where every parameter tells a tale, and every setting shapes the flow of urban water wisdom. 🚀🌍💡

Figure 1.   Rainfall and Losses One Watershed for a 100 Year Simulation with SWMM 5 Statistics at a saved time step of one hour.

Guidelines for Help Files and Examples

Guidelines for Help Files and Examples

I have written a lot of software and have used a lot of software in my
career. I thought it would be good for me to list some guidelines I
try to follow when using and making software. I emphasis the word
guidelines as I often do not follow these guidelines. Think Wish list
when you read guideline. I have actually learned a lot from using
software without access to the source code though knowing the source
code is always very helpful.

1. Some mention in the help file of the feature – at least some place to start the process of understanding.
2. Help file information to explain the background of the feature and common values for the parameters of the feature,
3. An example of how the feature is used – How do you even get it to work?
4. Rules and sensitivity of the feature – how is this feature linked to other features, what are the rules for using the feature and how sensitive is the feature?
5. An example of the feature along with 
6. A bullet list of how to use the feature 
7. How do I see if the feature is actually working?  Some options or features are not always used 
8. More to come in the future  

Runoff from One Watershed for a 100 Year Simulation with SWMM 5 Statistics for the Subcatchment Impervious and Pervious Depth

Introduction:  This set of blogs uses the 1000 year rainfall/runoff/hydraulics model that you can download at http://swmm2000.com/forum/topics/1000-year-simulation-with-rainfall-in-swmm-5 to show the inner workings of SWMM 5 and by extension InfoSWMM and H2oMap SWMM using a QA/QC version of SWMM 5 with extended graphics.   I always hope that seeing the inner workings of a SWMM 5 feature helps to understand the code, sensitivity and importance of a parameter.   It also helps show sometimes when a parameter is not important.  

Discussion:  In this blog we look at the Subcatchment Runoff Depth for the three types of Subcatchment Surfaces in SWMM 5:

1.       Impervious with depression storage
2.      Impervious without depression storage
3.      Pervious area with depression storage

As you can see in the graphs of depth (Figure 1) the pervious depth is often zero as the infiltration is greater than the continuous rainfall.  Of course this depends on the rainfall intensity, infiltration type and infiltration parameters.  If you perform a Statistical Analysis on the pervious depth at a saved time step of 1 hour you will find 2721 events over a threshold of 0.01 feet. 

Figure 1.   Runoff from One Watershed for a 100 Year Simulation with SWMM 5 Statistics for the Subcatchment Impervious and Pervious Depth

The Link Time Step in SWMM 5, InfoSWMM and H2OMap SWMM

Introduction:  This set of blogs uses the 1000 year rainfall/runoff/hydraulics model that you can download at http://swmm2000.com/forum/topics/1000-year-simulation-with-rainfall-in-swmm-5 to show the inner workings of SWMM 5 and by extension InfoSWMM and H2oMap SWMM using a QA/QC version of SWMM 5 with extended graphics.   I always hope that seeing the inner workings of a SWMM 5 feature helps to understand the code, sensitivity and importance of a parameter.   It also helps show sometimes when a parameter is not important.  

Discussion:  Here we look at the link time step for a 100 year simulation.   If you use the Variable Time Step in SWMM5 with the CFL Adjustment factor the program will compute the needed link time step at each simulation time step based on the last time steps depth, velocity and width.  The link time step is

Link Time Step = Adjustment Factor * CFL Explicit Time Step for the Controlling Link

The time step is larger for low flows and decreases as the flow in the link increases (Figure 1).     The time step ranges between the maximum step allowed by the user during the simulation and the time step lengthening value in the Dynamic Wave Tab of the Simulation options.  The program will use the minimum of the time steps for ALL links.  The minimum time step at each simulation step is multiplied by the Adjustment Factor.  The time steps used during the simulation are listed in the Routing Time Step Summary table where you can find the average, minimum and maximum time steps.  The smaller the Adjustment Factor the smaller the link time steps during higher flow.

Figure 1.  The Link Time Step over a 100 Year Period for Link Venant

InfoSewer Flow Attenuation Sensitivity

InfoSewer Flow Attenuation Sensitivity 

The three Run manager parameters, Maximum Number of Segments, Minimum Travel Distance and the Minimum Travel Distance in InfoSewer and H2OMAP Sewer affect the shape and flow attenuation of the flow in a link.  The effect of using the flow attenuation is to reduce the peak flow and spread out the flow compared to the No Flag option (Figure 1). 

Figure 1.  Effect of the Flow Attenuation Option in infoSewer and H2OMAP Sewer

How is Capillary Suction Head Used in SWMM 5 Green-Ampt?

Subject:   How is Capillary Suction Head Used in SWMM 5 Green-Ampt?

How sensitive is the infiltration loss and rate to the capillary suction head parameter in the SWMM 5 Green-Ampt  infiltration method.   Figure         1 shows how the total infiltration loss and total loss rate vary as you change the suction head from 12 to 6 to 3 inches.    Internally the suction head is used in infil.c of SWMM 5 by adding the suction head to the ponded water on the pervious area in the parameter c1 of the implicit Green-Ampt SWMM5 solution.

C1 =  (Suction Head + Depth of Ponded Water) * IMD or Initial Moisture Deficit

Figure 1.  The sensitivity of the total infiltration loss to the capillary suction head in a continuous simulation

How is the Soil Saturated Conductivity Used in SWMM 5 Green-Ampt?

Subject:   How is the Soil Saturated Conductivity Used in SWMM 5 Green-Ampt?

How sensitive is the infiltration loss and rate to the Soil Saturated Conductivity parameter in the SWMM 5 Green-Ampt  infiltration method.   Figure 2 shows how the total infiltration loss and total loss rate vary as you change the soil saturated conductivity from 1 to 0.1 to 0.01 inches/hour.  Internally, Ks is used to check saturation and in the computation of the soil infiltration rate. Two of the checks are:

·         In low rainfall everything infiltrates as irate less than Infil>Ks and
·         In the check to see if the soil is already saturated. 

 

Figure 1.  The three parameters for Green-Ampt Infiltration in SWMM 5

Figure 2.  The sensitivity of the total infiltration loss to the soil saturated conductivity in a continuous simulation

InfoSewer Minimum Travel Time Sensitivity

InfoSewer Minimum Travel Time Sensitivity

The three Run manager parameters, Maximum Number of Segments, Minimum Travel Distance and the Minimum Travel Time in InfoSewer and H2OMAP Sewer affect the shape and flow attenuation of the flow in a link.  The effect of decreasing the Minimum Travel Time is to reduce the peak flow and spread out the flow as the number of segments increases(Figure 1).  The larger the Minimum Travel Time, which has the effect of decreasing the number of segments in a link up the limit of the parameter Maximum Number of segments, the smaller the peak and the more attenuation of the flow in InfoSewer.

There is three ways to control attenuation in InfoSewer: (1) use the flow attenuation option, (2) increase the Maximum Number of Segments per link and (3) decrease the Minimum travel distance.    You can also use all three parameters to make more segments per link for long links and only a few segments for short links.

Figure 1.  Effect of the Minimum Travel Time in InfoSewer and H2OMAP Sewer

InfoSewer Maximum Number of Segments Sensitivity

InfoSewer Maximum Number of Segments Sensitivity

The three Run manager parameters, Maximum Number of Segments, Minimum Travel Distance and the Minimum Travel Distance in InfoSewer and H2OMAP Sewer affect the shape and flow attenuation of the flow in a link.  The effect of decreasing the Minimum Travel Distance is to reduce the peak flow and spread out the flow as the number of segments increases(Figure 1).  The smaller the minimum travel distance, which has the effect of increasing the number ofsegments in a link up the limit of the parameter Maximum Number of segments, the smaller the peak and the more attenuation of the flow in InfoSewer.

There is three ways to control attenuation in InfoSewer: (1) use the flow attenuation option, (2) increase the Maximum Number of Segments per link and (3) decrease the Minimum travel distance.    You can also use all three parameters to make more segments per link for long links and only a few segments for short links.

Figure 1.  Effect of the Minimum Travel Distance in InfoSewer and H2OMAP Sewer

Sensitivity Analysis in InfoSWMM and H2OMAP SWMM

Subject:  Sensitivity Analysis in InfoSWMM and H2OMAP SWMM   

  

It is easy to perform sensitivity analysis in InfoSWMM and H2oMAP SWMM using the Scenario Manager, Dataset manager, Block Edit in the Database Editor, Batch Simulation and theReport Manager.  For example, we will do a sensitivity analysis for the Subcatchment Width (one the physical parameters in the Subcatchment analysis of SWMM 5 – see Figure 1).  The width is normally the area divided by the overland path length but there are many common means of calculating the width.  

Figure 1.  Physical Data used in the Calculation of Surface Runoff using the Non Linear Reservoir Routing method in SWMM 5.

Figure 2.  The base scenario for our sensitivity analysis.

There are seven main steps in the sensitivity analysis of the width:

Step 1.   Use the Scenario Explorer to make Child Scenarios from the Base Scenario.  For ease of understanding we will name each of the Child Scenario's the percent change in the width parameter.  Thus, W-50, will be the Base Width Plus 50 percent.

Step 2.   Use the Dataset Manager to create different Subcatchment Sets that will be used for each of the Scenario's.  Again for ease of understanding we will use the name S_W+50 etc for the Sets to match the change in the Width Parameter.

Step 3.   Use the Scenario Manger to choose the right Subcatchment Set for Each Scenario.

Step 4.   Use the Database Editor to Edit and modify the Width of Each Subcatchment Set.

Step 5.   Use the Block Edit tool to multiply the Base Width Value by the needed value, 1.25, 1.50, 0.75, 0.50

Step 6.   Use the Batch Simulation Command to run all of the Scenario's.

                                               

Step 7.   Use Report Manager and the tool Compare Graphs to graph the results of Each Scenario together.

Step 8.   In Report Manager you can produce a table that shows the runoff for each of the different scenarios.