XPSWMM has powerful mapping functionalities for rendering the 2D results, and that can meet most common reporting and analysis needs.

For projects that will require customized mapping, it is common to export the results as GIS files and then using GIS software to create the maps.

One of the less known data format of 2D modeling is the mesh data format, a format that stores large spatial temporal dataset.

With native support of mesh data, 2D results can be rendered in QGIS with just a few clicks.

What is a mesh?

For XPSWMM, the most common mesh is the fixed 2D grid. And for…


Once you are good at something, everything feels so easy. Just like riding bikes and driving a car, you know what to do without even thinking about it. The feel of ease when working with a model is what I call intuitive.

When I first started my career, it is fascinating to watch my boss take a glance of a model and tell me what is wrong. Sometimes he would open one of his text books and show me an equation to explain the theory behind it.

He had a PhD in hydraulics and had been in the field for…


When I started live modeling about a year ago, I thought live modeling is nothing but automated modeling, once I get myself familiar with the IT aspect of things, I should be good to go.

It turned to be a lot more exciting than I expected, the more I know about live modeling the more I realized how different live modeling is from traditional modeling.

I’ll share my experiences and thoughts in a few blog posts, and I would like to hear what you think.

I’ll start with calibration, the task I am working right now.

Calibration Goals

When working on planning…


When it comes to customizing your modeling environment, sooner or later a modeler will need to write programs using computer languages. Many modelers have the impression that such tasks are only for the technology inclined types. In this article, I hope I can change your mind, I’ll show you can start to build power tools with just a few lines of SQL, and it reads just like plain English.

Switch upstream and downstream node IDs

The reverse all selected links tool works fine most of the time. However, some times, you only want to switch the IDs and not the inverts, how can you achieve that?


Many thanks to the opportunity of sharing my experiences of building collection model at the Water Talks today (9/14/2021) with Ryan Brown. Here is a summary of the talk.

Life Cycle of a Model

The life cycle of a model always starts with a problem. The owner of the utility or the customers of the utility are experiencing some “pains”, and need to improve the collection system to solve the problem.

So they reach out to a consultant who will assign a junior engineer to build a model and generate some results.

Then a senior engineer will review the results and propose a few recommendations…


Source: Innovyze support portal

The velocity vector shows how the water flows through the surface, it can be a great tool to help understand the causes and impacts of surface flooding when reviewing 2D simulation results.

Although XPSWMM has powerful rendering engine to show the 2D results, from time to time, engineers and communities might need to create maps in GIS software packages to combine other sources information and create customized maps. In this article, we will use QGIS to render the max. flow velocity vectors.

Rendering the velocity in QGIS takes just a few steps,

  1. Export the max. velocity…


Source: Innovyze Support Portal

If your XPSWMM model won’t open, here are a few things you might be able to do to recovery the model.

XPSWMM Model Files

Refer to the help for more information about the structure of the model database, and how model edits are saved to the files.

Here are a few important facts related to recovering a corrupted model,

  • XPSWMM stores the model data in a few files. When an XPSWMM model is open, everything is loaded into the memory, until the model is saved the model will not be updated on the hard drive.
  • XPSWMM also creates a…

Source: Innovyze Support Portal

XPSWMM/XPSTORM database can get corrupted from time to time, for example after a system crash. Corrupted database can lead to strange model errors that are hard to diagnose. If your model meet the following descriptions, you might want to rebuild your model.

  • For a 1D model with less than 100 nodes, the *.xp file should be less than 10M for most models. If your *.xp file is larger than 50M, usually it has a lot of historical information saved, which can make data corruption more likely.
  • Strange errors
  • Model might complain about missing values which are…

source: Innovyze Support Portal

Evaluating a collection system’s capacity is a critical task for planning and design projects. XPSWMM provides a wide range of tools for modeler to evaluate the system capacity.

Common tasks include checking the HGL of system to,

  • identify capacity issues of manholes without enough freeboard and pipes that are surcharged
  • understand the causes of the capacity issues, pipe too small or downstream restriction, etc.

Profile View

The most useful tool is the “dynamic long section” tool

To use this tool, first select a flow path. XPSWMM provides several ways to select a flow path in a network,

  1. right…

Mel Meng

Empowering Water Experts

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