> For the complete documentation index, see [llms.txt](https://swatplus.gitbook.io/io-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://swatplus.gitbook.io/io-docs/introduction-1/reservoirs/hydrology.res.md).

# hydrology.res

This file contains the reservoir hydrology parameters.

| Field                                                                   | Description                                                           |   Type  |  Unit | Default |    Range    |
| ----------------------------------------------------------------------- | --------------------------------------------------------------------- | :-----: | :---: | :-----: | :---------: |
| [name](/io-docs/introduction-1/reservoirs/hydrology.res/name.md)        | Name of the reservoir hydrology record                                |  string |  n/a  |   n/a   |     n/a     |
| [yr\_op](/io-docs/introduction-1/reservoirs/hydrology.res/yr_op.md)     | The year of the simulation that the reservoir becomes operational     | integer |  n/a  |    1    |    1-9999   |
| [mon\_op](/io-docs/introduction-1/reservoirs/hydrology.res/mon_op.md)   | The month of the simulation that the reservoir becomes operational    | integer |  n/a  |    1    |     1-12    |
| [area\_ps](/io-docs/introduction-1/reservoirs/hydrology.res/area_ps.md) | Reservoir surface area when reservoir is filled to principal spillway |   real  |   ha  |  1500.0 |   1-3000.0  |
| [vol\_ps](/io-docs/introduction-1/reservoirs/hydrology.res/vol_ps.md)   | Volume of water needed to fill the reservoir to principal spillway    |   real  |  ha-m |  1500.0 | 15.0-3000.0 |
| [area\_es](/io-docs/introduction-1/reservoirs/hydrology.res/area_es.md) | Reservoir surface area when reservoir is filled to emergency spillway |   real  |   ha  |  500.0  |  1.0-1000.0 |
| [vol\_es](/io-docs/introduction-1/reservoirs/hydrology.res/vol_es-1.md) | Volume of water needed to fill the reservoir to emergency spillway    |   real  |  ha-m |   55.0  |  10.0-100.0 |
| [k](/io-docs/introduction-1/reservoirs/hydrology.res/k.md)              | Hydraulic conductivity of the reservoir bottom                        |   real  | mm/hr |   0.0   |   0.0-1.0   |
| [evap\_co](/io-docs/introduction-1/reservoirs/hydrology.res/evap_co.md) | Reservoir evaporation coefficient                                     |   real  |  n/a  |   0.60  |   0.0-1.0   |
| [shp\_co1](/io-docs/introduction-1/reservoirs/hydrology.res/shp_co1.md) | Shape coefficient 1 for reservoirs                                    |   real  |  n/a  |   0.0   |             |
| [shp\_co2](/io-docs/introduction-1/reservoirs/hydrology.res/sho_co2.md) | Shape coefficient 2 for reservoirs                                    |   real  |  n/a  |   0.0   |             |