# `make.new_water`

[`make.new_water`](#digger.make.new_water) will modify an initial topobathymetric surface to add new water areas. This may be of use in areas that have experienced recent deglaciation or lakes with incomplete bathymetric observations. The following is typical usage for [`make.new_water`](#digger.make.new_water).

1. Prepare a topography file as a geotif.
2. Prepare or obtain a shapefile containing one or more polygons indicating the areas for which new water is desired.
3. Estimate the maximum water depth for new water and the side-slope angle to use near the shoreline between sea level and the maximum new water depth. Ensure that the geotif and shapefile have the same coordinate system.
3. Run [`make.new_water`](#digger.make.new_water) to modify the topobathymetry file. Inspect the output and adjust any input parameters as needed.
4. Depending on the use case, this function may be run before or after other ``digger.make`` functions to set up the initial conditions for a D-Claw simulation.

A code snippet that uses [`make.new_water`](#digger.make.new_water) may be found in the file `digger/examples/pre-run/harriman_fiord/make_new_water.py`. In this example, deglaciation has exposed additional water.

```{literalinclude} ../../../../../examples/pre-run/harriman_fiord/make_new_water.py
:language: python
```
:::{attention}
This code snippet is not fully self-sufficient. To reproduce the example, execute the code such that the relative path is correct. This may be done by executing the example script from within the directory in which it is located.
:::

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 to assist the user in refining the failure surface generated through [`make.new_water`](#digger.make.new_water).

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

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