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problem creating the 2d-grid in WMS 8.2!


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I’m a newbie with the GSSHA and trying to run GSSHA simulation, but get nowhere with creating a 2D-grid with the Create Grid command. I’m using WMS version 8.2

I’m following instructions in


I have a 25 m resolution DEM, and I have run the TOPAZ, created the basin and stream arcs, and made a polygon from the basin.

In Greate Grid window (after selecting the basin polygon), I have chosen a base cell size of 25m. Then I have chosen “interpolate from DEM” in the next prompt.

Instead of even grid, I get grid with cells that are 25 m wide but 1287 m “tall”. When I try to run GSSHA (after defining precipitation etc.), I get error: “The grid size specified in the project file 24,…m differs from the north-south dimension of the raster grid cells 1287,… m as calculated from the Watershed_Mask header. Check your data to make sure they agree.”

My DEM is of a very flat area, which has caused some problems before, but I don’t think the problem is with my DEM because I have the same problem when using DEMs from the tutorial file. Furthermore, I have managed to create the 2D-grid just fine from this DEM using WMS 8.1. Maybe there is something wrong with grid settings? I don’t remember touching any of the grid settings, but is there a way to return all settings to their original form?

I would be most grateful for any help anyone could give!

-Pirkko M.-

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Hi Pirkko,

There are a couple of ways to fix your problem. There is a problem with the current version of WMS 8.2 out there. When you try to create a grid using the "Create Grid" command from the menus, a grid is created that will not work for GSSHA. To create a grid using the current version, you should go to the create grid step in the hydrologic modeling wizard, which can be accessed from a button located at the bottom of the WMS screen. Selecting "Create Grid" from this step will build a grid that has the same dimensions in the X-Y directions.

The other thing I should say is that we are going to be posting an update to WMS 8.2 in the next couple of days that will fix the problem you are having with the "Create Grid" command. If you can wait a couple of days, you can download that update and create a grid just as you did in WMS 8.1 and it should work fine.

Hope this helps,


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