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description: Theoretical Maximum Habitat Scenario Habitat Methodology and Overview
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# Theoretical Maximum Habitat Methodology

**Theoretical Maximum Habitat Flow Area Curves**&#x20;

Habitat inputs for Reorienting to Recovery theoretical maximum habitat model run are scaled versions of existing habitat to area curves from the CVPIA SIT DSMhabitat data package.&#x20;

* `DSMhabitat::fr_spawn$biop_itp_2018_2019`
* `DSMhabitat::fr_juv$biop_itp_2018_2019`
* `DSMhabitat::fr_fry$biop_itp_2018_2019`
* `DSMhabitat::fr_fp$biop_itp_2018_2019`
* `DSMhabitat::fr_delta$biop_itp_2018_2019`

For each river in the SIT DSM, we calculated the theoretical maximum habitat for above and below dams or for unregulated rivers. See the [methodology]() document for an in-depth overview of theoretical maximum habitat modeling methods.

**Methods for Scaling the Curve**&#x20;

**1) Calculate the flow point of reference**

**Inchannel Habitat:** For in-channel habitat we use the flow associated with peak habitat on a given stream's flow to area curve.&#x20;

**Floodplain Habitat:** For floodplain habitat, we use a 2-year flow value, which represents a flow that is exceeded in 50% of the years between 1980 and 2000. We calculated the 2-year, 50% exceedence value by taking the yearly rolling maximum of monthly CalSim flows and applying a cumulative distribution function on the ranked values to find the proportion of all values less than or equal to the ranked order. An interpolation function is then developed to to find the 2 year flow value.

<figure><img src="https://2925377756-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FmkMyhLKiJA3OUPAQSMfW%2Fuploads%2FfK5mZOsDs9TWGUpAwc1j%2Fimage.png?alt=media&#x26;token=4cf65e95-4d49-43f2-b0aa-6f9e5d464ec6" alt=""><figcaption><p>Figure 1 - example comparison of calculated 2 year flow with the CalSim modeled monthly flow between 1980 and 2000 </p></figcaption></figure>

**2) Calculate the proportion increase of habitat at flow point of reference**

The proportion increase between baseline and theoretical maximum habitat was calculated using the following equation. The `existing_acres` were calculated using the median (for in-channel) and 2-year flows (for floodplain).

`proportion_increase = (max_hab_acres - existing_acres) / existing_acres + 1`

**3) Scale existing habitat by proportion increase**

The existing acres are then scaled for each watershed (`ws`) by the calculated `proportion_increase`.

`new_hab_acres <- DSMhabitat::fr_fp$biop_itp_2018_2019[ws , , ] * proportion_increase`

**4) Save new data objects for Theoretical Maximum Habitat**

The new data objects are saved in the package as:

* `DSMhabitat::fr_spawn$r_to_r_tmh`
* `DSMhabitat::fr_juv$r_to_r_tmh`
* `DSMhabitat::fr_fry$r_to_r_tmh`
* `DSMhabitat::fr_fp$r_to_r_tmh`
* `DSMhabitat::fr_delta$r_to_r_tmh` _see_ [_Delta methodology_](calculating-theoretical-maximum-habitat) _for theoretical maximum habitat_

**Comparison plots between Baseline and Theoretical Maximum Habitat**

**Spawning Habitat:**

<figure><img src="https://2925377756-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FmkMyhLKiJA3OUPAQSMfW%2Fuploads%2FZRzUheHdMdmLwSrTwAIb%2Fimage.png?alt=media&#x26;token=df75c19d-b9a5-4f9c-abab-5a59457ffb22" alt=""><figcaption></figcaption></figure>

**In-channel Juvenile Rearing Habitat:**

<figure><img src="https://2925377756-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FmkMyhLKiJA3OUPAQSMfW%2Fuploads%2Fa0IQI2O9kYpkNkVezI2j%2Fimage.png?alt=media&#x26;token=929a95aa-1c1d-482c-bb59-1105fef09d21" alt=""><figcaption></figcaption></figure>

**Floodplain Rearing Habitat:**

<figure><img src="https://2925377756-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FmkMyhLKiJA3OUPAQSMfW%2Fuploads%2FaO7fFnO02W4Z4WaP34YB%2Fimage.png?alt=media&#x26;token=8dd77ccb-bb54-4992-96ed-ea00f25041a3" alt=""><figcaption></figcaption></figure>

**Delta Habitat**

<figure><img src="https://2925377756-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FmkMyhLKiJA3OUPAQSMfW%2Fuploads%2FOyejSTJ0ACaOVIu4wR30%2Fimage.png?alt=media&#x26;token=480644d1-2c06-4d86-83cb-9b76441e1f14" alt=""><figcaption></figcaption></figure>
