# Hydrographs

SWAT+ prints two hydrograph output files per time step, one for incoming and one for outgoing hydrographs. The printing of hydrographs is controlled by entering "y" or "n" in the *hyd* line in [print.prt](https://swatplus.gitbook.io/io-docs/introduction-1/simulation-settings/print.prt). Hydrographs can be printed at daily, monthly, yearly, and average annual time steps. The names of the hydrograph output files are as follows: 

* hydin\_day.txt
* hydout\_day.txt
* hydin\_mon.txt
* hydout\_mon.txt
* hydin\_yr.txt
* hydout\_yr.txt
* hydin\_aa.txt
* hydout\_aa.txt

The number of lines in the hydrograph output files depends on the number of connections between spatial objects defined in the SWAT+ setup. In the incoming hydrograph files, for each receiving object there will be one line  per source object it receives a hydrograph from. The number of lines per source object in the outgoing hydrograph files equals the number of receiving objects it sends hydrographs to. 

{% tabs %}
{% tab title="In" %}

| **Field**    | **Description**                                 | **Unit** |
| ------------ | ----------------------------------------------- | -------- |
| jday         | Julian Day                                      | n/a      |
| mon          | Month                                           | n/a      |
| day          | Day of the month                                | n/a      |
| yr           | Year                                            | n/a      |
| name         | Name of the receiving object                    | n/a      |
| type         | Type of the receiving object                    |          |
| objtyp       | Type of the source object                       |          |
| typ\_no      | ID of the source object                         |          |
| hyd\_typ     | Type of the incoming hydrograph                 |          |
| fraction     | Fraction of the incoming hydrograph             |          |
| flo          | Incoming flow                                   | m3/s     |
| sed          | Incoming sediment                               | tons     |
| orgn         | Incoming organic nitrogen                       | kg       |
| sedp         | Incoming sediment phosphorus                    | kg       |
| no3          | Incoming nitrate nitrogen                       | kg       |
| solp         | Incoming soluble phosphorus                     | kg       |
| chla         | Incoming Chlorophyll-a                          | kg       |
| nh3          | Incoming ammonia nitrogen                       | kg       |
| no2          | Incoming nitrite nitrogen                       | kg       |
| cbod         | Incoming carbonaceous biochemical oxygen demand | kg       |
| dox          | Incoming dissolved oxygen                       | kg       |
| san          | Incoming sand                                   | tons     |
| sil          | Incoming silt                                   | tons     |
| cla          | Incoming clay                                   | tons     |
| sag          | Incoming small aggregates                       | tons     |
| lag          | Incoming large aggregates                       | tons     |
| grv          | Incoming gravel                                 | tons     |
| null         |                                                 |          |
| {% endtab %} |                                                 |          |

{% tab title="Out" %}

| **Field**     | **Description**                                 | **Unit** |
| ------------- | ----------------------------------------------- | -------- |
| jday          | Julian Day                                      | n/a      |
| mon           | Month                                           | n/a      |
| day           | Day of the month                                | n/a      |
| yr            | Year                                            | n/a      |
| name          | Name of the source object                       | n/a      |
| type          | Type of the source object                       |          |
| objtyp        | Type of the receiving object                    |          |
| typ\_no       | ID of the receiving object                      |          |
| hyd\_typ      | Type of the outgoing hydrograph                 |          |
| fraction      | Fraction of the outgoing hydrograph             |          |
| flo           | Outgoing flow                                   | m3/s     |
| sed           | Outgoing sediment                               | tons     |
| orgn          | Outgoing organic nitrogen                       | kg       |
| sedp          | Outgoing sediment phosphorus                    | kg       |
| no3           | Outgoing nitrate nitrogen                       | kg       |
| solp          | Outgoing soluble phosphorus                     | kg       |
| chla          | Outgoing Chlorophyll-a                          | kg       |
| nh3           | Outgoing ammonia nitrogen                       | kg       |
| no2           | Outgoing nitrite nitrogen                       | kg       |
| cbod          | Outgoing carbonaceous biochemical oxygen demand | kg       |
| dox           | Outgoing dissolved oxygen                       | kg       |
| san           | Outgoing sand                                   | tons     |
| sil           | Outgoing silt                                   | tons     |
| cla           | Outgoing clay                                   | tons     |
| sag           | Outgoing small aggregates                       | tons     |
| lag           | Outgoing large aggregates                       | tons     |
| grv           | Outgoing gravel                                 | tons     |
| null          |                                                 |          |
| {% endtab %}  |                                                 |          |
| {% endtabs %} |                                                 |          |