source: Innovyze Support Portal

GIS has many formats and from time to time you might have a GIS data format that your modeling software doesn’t support.

We will show a few common conversion tasks,

  • projection conversion
  • complex to simple geometry
  • format conversion

We will use ArcMap as an example for the conversion.

Projection Conversion

Projection might be the most confusing part of GIS data, the earth is a 3D sphere, and when drawing a map on a 2D surface, we’ll need complicated math models to define the earth shape, and then the rules how to project the 3D surface to a 2D…

source: Innovyze Support Portal

Ponding options for nodes can be confusing. You can find more about it from the online help.

Here is a quick summary,

  • None: any overflow will disappear
  • allowed: a quick and dirty way to get water stored above the node, and later the flow back to the system. Usually a more conservative way of sizing your system during very early stage of planning or design. In more detailed modeling, this option will be replaced with more realistic storage curves
  • sealed: if it is a sealed manhole or a structure that doesn’t allow overflow

So what about…

source: Innovyze Support Portal

If you are having trouble importing GIS files into your XPSWMM model, one possibility is that it has a geometry XPSWMM doesn’t support.

To test it,

  • create an empty model
  • then load the gis layer into XPSWMM

If nothing shows up in the map window, XPSWMM doesn’t support the shapefile.

The resolve the issue, we need to convert the shapefile into simple geometries.

Here is an example using ArcMap to fix the problem.

  1. load the shapefile into ArcMap
  2. Open the attribute table and check the geometry

source: Innovyze support portal

A common task for modeling is preparing rainfall data, and it could be complicated. In this example, we will learn a few tips of managing rainfall data.

Most common rainfall data are recorded from rain gauges, which is reported as totals for each time interval. For tipping bucket rain gauges, a very clever mechanical device, it counts the number of bucket tipping, since each time it tips, it is a fixed volume, the total rainfall can be calculated.

If the rain gauge reports the rainfall every 15 minutes, the data will look something like this.

source: Innovyze Support Portal

Evaporation in XPSWMM applies to the SWMM runoff. As shown below, SWMM uses the non-linear reservoir to model runoff for subcatchment.

ds is the depression depth, d is the water depth on the subcatchment. When it rains, water will start to pond on the subcatchment surface, and at each time step, and standing water will lose depth based on the evaporation rate. If the evaporation is given as 0.1 in/day, then it will translate into a depth based on the time step for the water to be removed from the subcatchment. At the same time, infiltration…

source: Innovyze Support Portal

When the underground system is overwhelmed, significant amount of flow can overflow to the surface through manholes, but the manhole might not be designed as an inlet to collect surface water.

Under such situation how should we model the node?

It turned out to be quite simple,

  1. Link the Spill Crest to 2D: this will allow flow to be exchanged between the node and the surface
  2. check Inlet Capacity
  3. Set the maximum Capacity to 0: this will limit the flow from surface to node to 0

To illustrate the impact, here is an example.

The 2D…

source: Innovyze Support Portal

When running a real-time live model, there is a need to collate the rainfall from multiple rainfall sources to get the best rainfall data.

A typical situation in the United States is using the rain gauges installed in the study area when data are available, and then using the radar rainfall (NEXRAD) when needed, and for forecasting use HRRR from NOAA.

Since we don’t have the time to review the rainfall data manually every time a real-time model is running, ICM has built-in functions to help identify data gaps, and then apply rules on how to…

source: Innovyze Support Portal

When using the XPTables, you can hide a column by right click the header of the column. But there is no unhide button.

To unhide the column,

  1. click “Set table variables”
  2. select the column that is hidden
  3. Click on the “Ab” format button
  4. Check “Visible”

source: Innovyze Support Portal

In part 1, we setup two models, one uses NEXRAD, and the other uses a single rain gauge from a time series stored in a TSDB.

What if we want to use both the rain gauge data and the NEXRAD rainfall in the same model, for areas close to the rain gauges, we would like to use rain gauges, and for areas too far away we would like to use the NEXRAD.

Turn rain gauges into Spatial rainfall Polygons

In part 1, we created two TVD connectors for the two rain gauges as points and used the rainfall profile in the subcatchment properties…

Mel Meng

Empowering Water Experts

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