# `make.breach`

[`make.breach`](#digger.make.breach) will modify an initial topobathymetric surface by adding a breach based on user-provided polylines. The following is typical usage for [`make.breach`](#digger.make.breach).

1. Prepare a topography file as a geotif.
2. Prepare a polyline shapefile that contains information about the start and end points of each breach. Ensure that the geotif and shapefile have the same coordinate system.
3. Run [`make.breach`](#digger.make.breach) to generate input files for D-Claw. Inspect the output and adjust any input parameters as needed.
4. Using these files, set up a D-Claw simulation to run and analyze. `digger` will not do this for you.

A code snippet that uses [`make.breach`](#digger.make.breach) may be found in the file `digger/examples/pre-run/black_lake/make_breach_black_lake_example.py`. In this example, a synthetic breach is placed across a road.

```{literalinclude} ../../../../../examples/pre-run/black_lake/make_breach_black_lake_example.py
:language: python
```

After this code runs, it will produce geotif and [topotype3](https://www.clawpack.org/topo.html) files that specify the modified topobathymetry.

It will also create diagnostic figures.

The standard diagnostic figure from [`make.breach`](#digger.make.breach)

```{figure} ../../../../_static/from_examples/breach.png
:alt: Example digger.make.breach summary figure.

An example of the diagnostic output provided by digger.make.breach.
```