# Adding a source representing groundwater

In this section an [Input ](https://water-strategy.gitbook.io/water-strategy/modelling-fundamentals/node-types/input-node)node representing a groundwater source will be added to the reservoir system. The demand node will receive water from both groundwater and the reservoir. Groundwater is modelled as a yield.

1. Clone the **'Demand with treatment losses'** scenario and call the new one **'Demand with GW'**
2. Add an **Input** node below the demand node as shown below. Rename the node to 'Groundwater well'
3. Please note that to maintain the same behaivior in each of the previous scenarios, the Max Fow of the input node must be set to 0 in each scenario. \
   \
   This can be done by clicking on the edit button on the Max Flow attribute of the Input node.

<figure><img src="https://530325344-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FOe4DHiaeqejzGopyV9BO%2Fuploads%2FwQAafk8kY1zVjWeHi6d2%2Fimage.png?alt=media&#x26;token=cc0bf1f3-5a4a-4a1e-a068-3183d4505908" alt=""><figcaption></figcaption></figure>

and then by setting a Max Flow of 0 Mm3/day in the text box:

<figure><img src="https://530325344-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FOe4DHiaeqejzGopyV9BO%2Fuploads%2FKTFEZpwKS62HYI1CLJ2k%2Fimage.png?alt=media&#x26;token=bd6b6f05-13b7-4fd9-803d-23008c20a33d" alt=""><figcaption></figcaption></figure>

and before saving the changes, select all scenarios so the 0 flow applies to all scenarios:

<figure><img src="https://530325344-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FOe4DHiaeqejzGopyV9BO%2Fuploads%2F88VhbW6fblI2Vpi5IGyQ%2Fimage.png?alt=media&#x26;token=7d8d65eb-2ad9-4fe3-bde2-131ed8f70ad1" alt=""><figcaption></figcaption></figure>

and then click on **save**.

<figure><img src="https://530325344-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FOe4DHiaeqejzGopyV9BO%2Fuploads%2F0B6DFf8t9oPfZ5PZ1ZxH%2Fimage.png?alt=media&#x26;token=7ab5b69e-26fb-4cda-9a31-31c591d1ed42" alt=""><figcaption></figcaption></figure>

<figure><img src="https://530325344-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FOe4DHiaeqejzGopyV9BO%2Fuploads%2Fiw1XJaW5hP2gDvqs3xn8%2Fimage.png?alt=media&#x26;token=1823486f-0a16-41d6-97e9-e6c319377b48" alt=""><figcaption></figcaption></figure>

3. Next, we need to set the yield of the groundwater in this scenario. Set the **Max Flow** of the node to be **0.02 Mm3/day** instead of &#x30;**.** This will represent the maximum possible supply of the input node at each time step.

<figure><img src="https://530325344-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FOe4DHiaeqejzGopyV9BO%2Fuploads%2FH9WHchSCJFwkZZNxg0Go%2Fimage.png?alt=media&#x26;token=3a6930e5-84ed-4787-ba4d-b73d731005f8" alt=""><figcaption></figcaption></figure>

4. Run this scenario.

<figure><img src="https://530325344-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FOe4DHiaeqejzGopyV9BO%2Fuploads%2FMiW7bSQ6fcTAXCPzLKbo%2Fimage.png?alt=media&#x26;token=8bcf094a-36d0-4f1c-a790-77541b58902b" alt=""><figcaption></figcaption></figure>

5. Compare the **simulated\_volume** of the reservoir to that of the **'Demand with treatment losses'** scenario.

<figure><img src="https://530325344-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FOe4DHiaeqejzGopyV9BO%2Fuploads%2FdjkcMuBTxncwkeAc8Xga%2Fimage.png?alt=media&#x26;token=3fb72f91-88be-4f95-9c00-9f18749d21bc" alt=""><figcaption></figcaption></figure>



<figure><img src="https://530325344-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FOe4DHiaeqejzGopyV9BO%2Fuploads%2F1eBaXctzhA2sxmmQdIfm%2Fimage.png?alt=media&#x26;token=d33a3084-695a-4038-ad05-a3646242169b" alt=""><figcaption></figcaption></figure>



## Exercises and questions

