Thursday, August 31, 2023

Unpacking the Two-Pass Solution in InfoSewer


Unpacking the Two-Pass Solution in InfoSewer

InfoSewer's dual-pass methodology is a cornerstone for achieving a meticulous and comprehensive analysis of sewer system performance. The two distinct passes each offer a layer of insight into various facets of the system, particularly focusing on the depth-to-diameter ratio (d/D) and the Hydraulic Grade Line (HGL).

Phase 1: Laying the Groundwork with Manhole Loads and Link Flows

The first pass serves as the initial survey, setting the stage for the entire simulation. During this phase, InfoSewer calculates the loads for each manhole and estimates the flow dynamics in the links connecting them.

  • Key Output: The primary yield from this stage is the initial d/D values, which are often used for preliminary mapping.
  • Primary Focus: At this juncture, the main attention is given to calculating manhole loads and estimating link flows.
  • Use-case: This is especially useful for generating an initial hydraulic snapshot of the sewer network, which can be invaluable for early-stage planning and decision-making.

Phase 2: Advancing the Analysis with Backwater, Surcharge, and Pressure

The second pass builds upon the foundational data gathered in the first. This phase engages in a more nuanced analysis by incorporating calculations for backwater effects, surcharge conditions, and intra-system pressure.

  • Key Output: The adjusted d/D values and the HGL emerge as the critical outputs from this phase.
  • Primary Focus: The emphasis here is on advanced hydraulic modeling, including backwater estimation, surcharge analysis, and pressure calculations.
  • Use-case: The second pass is vital for risk assessments, emergency response planning, and other high-stakes decision-making processes.

Interplay Between the Two Phases

The two passes are not isolated events but rather interdependent processes that feed into each other. The second pass takes the first-pass data as a baseline but refines it to account for the more intricate hydraulic phenomena, often resulting in higher adjusted d/D values.

Why Adjusted d/D Matters

The adjusted d/D, born out of the second pass, usually exceeds the initial d/D computed during the first pass. This variation is not arbitrary but indicative of the complex hydraulic factors like backwater effects and surcharging that were considered in the second pass. As such, the adjusted d/D serves as a more reliable and nuanced metric for assessing system performance and associated risks.

This expanded perspective offers a multi-dimensional view of the Two-Pass Solution in InfoSewer, shedding light on its nuances, capabilities, and the significance of each stage in contributing to a robust and reliable sewer system model.

Tuesday, July 4, 2023

SWMM 5.2.3 Inlet Workflow from the Help File

SWMM 5.2.3 Inlet Workflow from the Help File

The process of conducting an inlet analysis using the Storm Water Management Model (SWMM) is quite thorough and systematic. Here, we provide a detailed expansion of the general workflow you've presented, demonstrating how to apply it to a simple street and sewer drainage system:

  1. Layout both the street and sewer networks: Begin by designing and sketching your street and sewer networks. This involves determining the locations of your roads, open channels, and sewer lines, as well as their interconnections. This layout forms the fundamental skeleton for your model. You can use GIS (Geographical Information System) data or manual drafting to aid in creating the layout.

  2. Assign subcatchment runoff and user-defined inflows to individual street nodes: Next, designate the runoff from surrounding land areas (subcatchments) and any user-defined inflows to the nodes within your street network. Runoff is the water flow that occurs when soil is infiltrated to full capacity and excess water from rain, meltwater, or other sources flows over the land. User-defined inflows could be point sources of water other than the subcatchment runoff. This assignment takes into account how rainfall will be distributed in the area and which roads it will likely flow down.

  3. Create a collection of Street cross-sections: Design a collection of street cross-sections. These cross-sections represent a vertical slice through the street, showing elements such as the roadway, sidewalks, and gutters. The cross-sections provide a detailed view of the street’s shape and slope, which are key factors influencing how stormwater flows.

  4. Assign specific Street cross-sections to individual street conduits: Each conduit in your street network should be assigned a specific cross-section from your collection created in the previous step. The assignment should accurately represent the actual structure of the street at the conduit's location.

  5. Create a collection of Inlet designs: After dealing with the streets, focus on creating a variety of inlet designs. These inlets are structures that allow stormwater to enter the drainage system from the street surface. They can have different designs depending on their size, shape, and the specific conditions they will be handling.

  6. Assign specific Inlet designs to selected streets: Once you have a collection of inlet designs, assign them to the specific streets within your network. Inlet placement depends on factors such as street slope, expected water flow, and city planning guidelines.

  7. Set appropriate analysis options and run a simulation: Configure the parameters for the SWMM analysis according to the objectives of your study, including the simulation duration, time steps, and any specific routing or runoff methods. Then, execute the simulation, which will use the SWMM algorithms to model how stormwater will flow through your designed network.

  8. Review the simulation results to see if flow spread and depth values are acceptable: After the simulation has run, assess the results. Examine key outputs like flow spread (the width of water flow on a street) and depth values at each inlet and node. Ensure that these values are within acceptable ranges as defined by your design standards. If the results are not satisfactory, you may need to revisit and revise your design, which may include altering the street layout, changing the assigned cross-sections, or modifying the inlet designs.

This detailed procedure offers a step-by-step guide to designing and analyzing a basic street and sewer drainage system using SWMM. It's essential to remember that real-world scenarios may require additional steps or considerations, depending on the specificities of the site, climate conditions, and regulatory requirements.

Inlets from the SWMM 5.2.3 help file

 Inlets from the SWMM 5.2.3 help file 

The Storm Water Management Model (SWMM) is a powerful hydrological simulation program, used for planning, analysis, and design related to stormwater runoff, combined sewers, sanitary sewers, and other drainage systems. This software models various components of these systems, including pipes, channels, and inlets. When modeling inlets with SWMM, you should consider the following key concepts:

  1. Inlet Assignment: Inlets are assigned to conduit links that represent either streets or open channels. In this context, conduits are used to represent the physical structures that carry flow in the drainage system, such as pipes, channels, and tunnels. Therefore, each inlet, representing a point of entry for stormwater into the system, needs to be linked to a specific conduit.

  2. Inlet Type and Conduit Cross-section: The type of inlet you choose is determined by the cross-section of the conduit it is assigned to. For instance, curb and gutter-type inlets are designated to conduits with a street cross-section. Meanwhile, drop inlets are used with conduits that have either a rectangular or trapezoidal cross-section. Alternatively, custom inlets can be placed in any type of conduit, providing greater flexibility in modeling.

  3. Node Assignment: Each inlet is assigned to a node, typically part of a sewer line, that will receive the flow captured by the inlet. A node represents a junction point in the system where the flow may divide or combine.

  4. Multiple Inlets: Multiple inlets of the same design and receptor node can be assigned to a single conduit. This is particularly useful when modeling two-sided streets. For on-grade placement, the flow captured by each inlet is determined sequentially, which means the flow approaching the next inlet in line is the bypass flow from the inlet before it.

  5. Inlet Operation: Users can determine whether an inlet operates on-grade, on-sag, or let SWMM decide based on the street layout and topography. An on-grade inlet is situated on a continuous grade, while an on-sag inlet is located at a sag or sump point. The latter is an area where all adjacent conduits slope towards the inlet, leaving no place for water to flow except into the inlet.

  6. Flow Capture: Flow capture for on-grade inlets is determined by the approach flow seen by the inlet. However, for on-sag inlets, it is a function of the depth of water at the sag point node. This distinction is crucial for correctly modeling the flow behavior.

  7. Clogging and Flow Capture Restriction: Inlets can be assigned a degree of clogging and a flow capture restriction. These factors account for potential real-world conditions that may impede the flow into the inlet, providing a more accurate representation of the system’s functionality.

Thursday, June 15, 2023

Good Science Writing Tips from HBR

 Source -


“Keep it simple.” This classic piece of writing advice stands on the most basic neuroscience research. Simplicity increases what scientists call the brain’s “processing fluency.” Short sentences, familiar words, and clean syntax ensure that the reader doesn’t have to exert too much brainpower to understand your meaning.


Specifics awaken a swath of brain circuits. Think of “pelican” versus “bird.” Or “wipe” versus “clean.” In one study, the more-specific words in those pairs activated more neurons in the visual and motor-strip parts of the brain than did the general ones, which means they caused the brain to process meaning more robustly.


Our brains are wired to make nonstop predictions, including guessing the next word in every line of text. If your writing confirms the readers’ guess, that’s OK, though possibly a yawner. Surprise can make your message stick, helping readers learn and retain information.

Stirring Language

You may think you’re more likely to persuade with logic, but no. Our brains process the emotional connotations of a word within 200 milliseconds of reading it—much faster than we understand its meaning. So when we read emotionally charged material, we reflexively react with feelings—fear, joy, awe, disgust, and so forth—because our brains have been trained since hunter-gatherer times to respond that way. Reason follows. We then combine the immediate feeling and subsequent thought to create meaning.


As humans, we’re wired to savor an­tic­ipation. One famous study showed that people are often happier planning a vacation than they are after taking one. Scientists call the reward “anticipatory utility.” You can build up the same sort of excitement when you structure your writing. In experiments using poetry, researchers found that readers’ reward circuitry reached peak firing several seconds before the high points of emphatic lines and stanzas. Brain images show preemptive spikes of pleasure even in readers with no previous interest in poetry.

Smart Thinking

Making people feel smart—giving them an “aha” moment—is another way to please readers. To show how these sudden “pops” of insight activate the brain, researchers have asked people to read three words (for example, “house,” “bark,” and “apple”) and then identify a fourth word that relates to all three, while MRI machines and EEGs record their brain activity. When the study participants arrive at a solution (“tree”), brain regions near the right temple light up, and so do parts of the reward circuit in the prefrontal cortex and midbrain. The readers’ delight is visible. Psychological research also reveals how people feel after such moments: at ease, certain, and—most of all—happy.

Social Content

Our brains are wired to crave human connection—even in what we read. Consider a study of readers’ responses to different kinds of literary excerpts: some with vivid descriptions of people or their thoughts, and others without such a focus. The passages that included people activated the areas of participants’ brains that interpret social signals, which in turn triggered their reward circuits.


Few things beat a good anecdote. Stories, even fragments of them, captivate extensive portions of readers’ brains in part because they combine many of the elements I’ve described already

Sunday, May 28, 2023

Blog strategy to explain complex modeling concepts to non-modelers, while highlighting the beauty and majesty of domain knowledge:

Blog strategy to explain complex modeling concepts to non-modelers, while highlighting the beauty and majesty of domain knowledge:

  1. Title: "Simplifying Complexity: Unveiling the Beauty and Mastery of Hydrological Modeling"

  2. Introduction: Start by providing a brief overview of what hydrological modeling is and why it's important. Use relatable language and analogies to draw in your audience.

  3. Identify Your Audience's Needs: You're writing for non-modelers, so identity what they need to understand about modeling. What concepts are crucial for them to grasp? What misconceptions might they have?

  4. Break Down Complexity: Break down the complex modeling concepts into simpler, understandable parts. Use analogies or real-world examples to explain these concepts. For instance, you could compare the movement of water in a watershed to traffic flow in a city to explain runoff.

  5. Visualize It: Use visuals to make complex concepts easier to understand. Diagrams, charts, or animations can all be great tools for this. Even a well-placed infographic can do wonders to simplify complex ideas.

  6. Highlight the Beauty: Talk about the elegance of the mathematical models, the way they mimic real-world processes, and the surprising insights they can provide. This is where you can really showcase the "beauty and majesty" of your domain knowledge.

  7. Interactive Elements: Incorporate interactive elements if possible, such as simulations that readers can manipulate. This can help your audience intuitively understand how different factors influence the model.

  8. Case Studies: Use real-world examples or case studies to show the practical applications of these models. Stories can be a powerful tool for making abstract concepts concrete.

  9. Glossary: Include a glossary of key terms that you've simplified for your readers. This can serve as a quick reference guide for readers who may be unfamiliar with certain terms.

  10. Conclusion: Summarize the main points and emphasize the importance of understanding these models, even for non-modelers. End on a note that invites discussion or further inquiry.

  11. Invitation to Engage: Encourage your readers to ask questions or share their thoughts in the comments. This can be a great way to engage your readers and help them learn more.

Remember, the goal is not to turn your readers into modelers but to help them appreciate the beauty and complexity of the models and understand their significance.

Unpacking the Two-Pass Solution in InfoSewer

  Unpacking the Two-Pass Solution in InfoSewer InfoSewer's dual-pass methodology is a cornerstone for achieving a meticulous and compreh...