.. _examples-single-reservoir-setqexample:

``set_q`` Scheme Example
========================

This example shows how to use the :py:meth:`.ReservoirModel.set_q` scheme when modelling a single reservoir model.

.. note::

      For details about the full model file structure please see :ref:`examples-single-reservoir-basic`.

We consider a reservoir with a single inflow, ``Q_in``, and a single outflow ``Q_out``.
The reservoir outflow is determined based upon the reservoir elevation, ``H``, at each timestep.

.. math::

   Q_{out} =
    \begin{cases}
      0.4 & \text{if $H > 1598.54$}\\
      0.2 & \text{otherwise}\\
    \end{cases}

The :py:meth:`.ReservoirModel.set_q` scheme can be applied to model these operations. 

.. note::

      There are many options which can be chosen when applying the :py:meth:`.ReservoirModel.set_q` scheme. 
      For other example implementations please see also :ref:`examples-single-reservoir-rainevapexample` and 
      :ref:`examples-single-reservoir-passflowexample`.

Main Model (python) File
------------------------

An example of the main model file `set_q_example.py` is given below.

.. literalinclude:: ../../../../examples/set_q_example/set_q_example.py
  :language: python
  :lineno-match:

The template file mentioned in the :ref:`examples-single-reservoir-basic` will look very similar to this file,
except that the :py:meth:`apply_schemes` method still needs to be filled out.

The line

.. literalinclude:: ../../../../examples/set_q_example/set_q_example.py
  :language: python
  :start-at: CONFIG
  :end-at: CONFIG

sets the model configuration.
This model configuration is defined by the base directory ``base_dir``.
In most cases, the base directory is ``Path(__file__).parent``,
which is the directory of the current file.

The line

.. literalinclude:: ../../../../examples/set_q_example/set_q_example.py
  :language: python
  :start-at: class
  :end-at: class

defines a class :py:class:`.SingleReservoir`
that inherits all properties and functionalities
of the predefined class :py:class:`.ReservoirModel`.
An overview of this class can be found in :ref:`reservoir-api`
and details of the underlying model it uses can be found in :ref:`single-reservoir-model`.

The method :py:meth:`.ReservoirModel.apply_schemes` is called every timestep and contains the logic
for which schemes are applied.
The first argument ``self`` is the :py:class:`.SingleReservoir` object itself.
Since :py:class:`.SingleReservoir` inherits from :py:class:`.ReservoirModel`,
``self`` can call any of the :py:class:`.ReservoirModel` methods, such as
:py:meth:`.ReservoirModel.get_var` and
:py:meth:`.ReservoirModel.set_q`.
An overview of all available :py:class:`.ReservoirModel` methods
can be found in :ref:`reservoir-api`.

In this example, the :py:meth:`.ReservoirModel.apply_schemes` method starts
by collecting the current reservoir elevation as this is used to determine operations. 
The method then checks if the elevation H is higher than threshold value 1598.54.
The :py:meth:`.set_q` scheme is then applied to set the reservoir outflow equal to a value of 0.2 or 0.4 based
on whether the defined elevation threshold is exceeded.

Lookup tables
-------------

This model uses only the standard lookup table ``h_from_v``,
for other lookup tables, defaults from the generated template files can be used. 

.. note::

      For details about the lookup tables please see :ref:`examples-single-reservoir-basic`.

Input Data Files
----------------

.. note::

      For details about input file structure please see :ref:`examples-single-reservoir-basic`.

Output Data
-----------

The results of the simulation will appear in the `output` folder
in a file called `timeseries_export.xml`.
The data is linked to model variables via the `rtcDataConfig.xml`
in the same way as with `timeseries_import.xml`.

Automatic Plotting
------------------

You can optionally include a `plot_table.csv` in the input folder.
This is used by the rtc-tools-interfaces module (automatically installed with this package)
to plot the model output.
For more details on how to use this file and visualize results,
see `RTC-Tools-Interface <https://gitlab.com/rtc-tools-project/rtc-tools-interface>`_.

The results of the simulation run can be seen in the plot below.

.. raw:: html
    :file: figures/final_results_setq.html