Gridding the Horizontal Mesh

The format of the SCHISM horizontal mesh is described in the SCHISM manual.

Users will find that SCHISM projects require refinement or extension. There are a few reasons:

  • SCHISM modeling is often used for

    • focused analysis, requiring refinement

    • sea level rise, requiring upstream extension or gridding of exposed areas.

    • restoration areas.

  • The spatial parameterization is varied or parameterized, so there is no extensive “calibration” of a new mesh

Here we will cover:

  • Best practices for horizontal gridding

  • Attaching boundaries

  • Checklist for after changing the grid or boundaries.

  • Vertical grid.

Meshing

Meshing considerations for SCHISM

Video (Joseph Zhang, SCHISM summit)

Video (Joseph Zhang #2)

Recap/checklist

Getting to know SMS

Please see Aquaveo SMS learning center for videos, tutorials, wiki, courses, and blog. The CA-DWR Delta Modeling Section has posted a series of videos to be used for learning how to use SMS for SCHISM mesh generation. You can see the complete playlist here: DMS SCHISM Gridding Playlist

Here’s the introductory SMS video by Eli Ateljevich:

Sample Data

Recap checklist

Presentation: clip_dems and efficient use of DEMS

Building the Bay-Delta mesh the standard way

Here’s the SMS 2dm generation overview video by Eli Ateljevich:

Presentation: Meshing consideration for marshes and restoration

Merging/Stitching SMS mesh/maps (new work, flooded islands, etc)

Video

Recap/checklist

Vertical mesh setup

Checklist for after you change the mesh

Changing the mesh tends to have consequences in places people forget to think about, though most are straightforward or obvious. This is a checklist of gotchas that arise outside the gridding environment.

☐ Are boundaries still in the proper place?

☐ If boundaries moved, is depth enforcement preventing dry boundaries still in right place?

☐ Are flow cross sections in changed area still aligned?

☐ Are the node pairs that define hydraulic structure locations still correct?

☐ Are polygons used to define spatial inputs appopriate for new area?

☐ If grid was extended, do yaml polygons cover extended domain?

☐ Are sources excluded?

☐ Do you have submerged aquatic vegetation? Assumptions? Consider changing those file

☐ Old hotstarts not valid on new mesh, utilities will interpolate on new grid

☐ Old nudging files not valid on new mesh. Re-do.

☐ If refining/coarsening extensively on main channel, consider the effect on momentum and the algorithm.

☐ Mesh quality:

☐ Skew and area warnings in preprocessor.