> For the complete documentation index, see [llms.txt](https://water-strategy.gitbook.io/waterstrategy/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://water-strategy.gitbook.io/waterstrategy/modeling-basics/parameters/interpolation-parameters/interpolated-volume.md). # Interpolated Volume {% embed url="" %} Video using the Interpolated Volume Parameter {% endembed %} ## General Description Generic interpolation parameter that returns a value based on a Reservoir or Storage nodes current (time step) volume. The parameter uses an **array** (table) of **Reservoir Volumes** and corresponding values. In this case the associated values are the corresponding **Reservoir Area** for a given **Volume**. Interpolation is used to calculate values betwen points given in the interpolation array. [ API Reference](https://pywr.github.io/pywr-docs/master/api/generated/pywr.parameters.InterpolatedVolumeParameter.html#pywr.parameters.InterpolatedVolumeParameter) ## Attributes

Name	Description	Required
type	interpolatedvolume	Yes
node	Storage node to provide input volume values to interpolation calculation	Yes
volumes	x coordinates of the data points for interpolation	Yes
values	y coordinates of the data points for interpolation	Yes
interp_kwargs	Dictionary of keyword arguments to pass to scipy.interpolate.interp1d class and used for interpolation	Optional

## Example The following Json shows an example Area vs Volume rating cure for a reservoir. This could be used to define the Area attribute of a Storage or Reservoir node. ```json { "type": "InterpolatedVolumeParameter", "node": "Reservoir or Storage node name", "volumes": [ 0, 7, 10, 15, 25 ], "values": [ 1, 2, 4, 6, 14 ], "interp_kwargs": { "kind": "linear" }, "comment": "volumes: Mm3, values: Km2" } ``` The Json represents the table below:

Volume (Mm3)	Area (Km2)
0	1
7	2
10	4
15	6
25	14

When plotted it looks like this: Below is an example Area rating table

Volume (Mm3)	Area (Km2)
0	1
7	2
10	4
15	6
25	14

When plotted it looks like this

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