# mesh-zmin v3.2.3

**Mercurial revision 5786:5c8b45563631 | 2026-08-04**

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## Description

`mesh-zmin` applies a **minimal depth** to the topographic file of a mesh. This tool ensures that shallow depths in the mesh are adjusted according to a specified minimum threshold, optionally using a bathymetry file or a polygon file to limit the working area.

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## Usage

```bash
mesh-zmin [OPTIONS] -m mesh_file topo_file
```

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## Options


| Option          | Description                                                                                                                                                                        |
| --------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `-h`, `--help`  | Show this help and exit.                                                                                                                                                           |
| `-m <file>`     | **Required.** Path to the mesh file (e.g., `mesh.nei`).                                                                                                                            |
| `-o <rootname>` | Output rootname. Default: `topo`.                                                                                                                                                  |
| `-b <file>`     | Path to the bathymetry file. If provided, mesh depths shallower than `zmin` are replaced by this bathymetry if it is deeper than `zmin`. Outputs a `<output>-zmin_bathy.s2r` file. |
| `-p <file>`     | Path to the polygon file to limit the working area. Outputs a `<output>-zmin_polygon.s2r` file.                                                                                    |
| `-hmin <value>` | Minimal depth in meters. **Default:** `2`. Used only if `-b` or `-p` is specified.                                                                                                 |


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## Examples

### Apply Minimal Depth Using Bathymetry

Apply a minimal depth of **0.5 meters** using a bathymetry file:

```bash
mesh-zmin -m mesh.nei -b bathymetry.grd -hmin 0.5 topo-00.s2r
```

### Apply Minimal Depth Using Polygon

Apply a minimal depth of **0.5 meters** within a polygon-defined area:

```bash
mesh-zmin -m mesh.nei -p polygon.plg -hmin 0.5 topo-00.s2r
```

### Default Minimal Depth

Apply the default minimal depth (`2 meters`) using a bathymetry file:

```bash
mesh-zmin -m mesh.nei -b bathymetry.grd topo-00.s2r
```

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## Environment Variables

This tool does not use any specific environment variables.

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## Notes

1. **Input Files:**
  - The `-m` option is **required** to specify the mesh file.
  - The `topo_file` argument is **mandatory** and represents the input topographic file to process.
2. **Output Files:**
  - If `-b` is used, the tool generates a `<output>-zmin_bathy.s2r` file.
  - If `-p` is used, the tool generates a `<output>-zmin_polygon.s2r` file.
  - If no `-o` is specified, the default output rootname is `topo`.
3. **Minimal Depth (`-hmin`):**
  - Only applies if `-b` or `-p` is specified.
  - Default value: `2 meters`.
4. **Error Handling:**
  - If the mesh file is not specified, the tool will abort with an error.
  - If the bathymetry file cannot be loaded, the tool will exit with an error.

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## See Also

- [Mesh File Formats](https://www.comodo-ocean.fr/) (for compatible mesh file formats)
- [Bathymetry Data Standards](https://www.ngdc.noaa.gov/mgg/bathymetry/) (for bathymetry file requirements)