.. _module4:

Module 4: Overview
-------------------

This module’s directory (“./module_data/**m4_requestoutput**”) contains a sample of model input files that you will need to edit in order to change what outputs are produced in Hello SCHISM.

Adding Flow Observation Transects
``````````````````````````````````

As seen in "FIGURE" there are 2 transects already specified in the model with the **flowlines.yaml** file, which creates the **fluxflag.prop** file. You will add a 3rd transect to capture flow through A LOCATION as shown below:

.. _obs_xs_req:

.. figure:: /img/schism_obs_transects.png
   :alt: Hello SCHISM Input Transects
   :align: center

   *Hello SCHISM observation transects as specified by the fluxflag.prop file*

The coordinates for the transect you will add will be one line straight down the center of the grid.

.. code-block:: text

   - [15587.5, -10294.] 
   - [15885.9, 10294.] 

1.	Open 'flowlines.yaml’ in an editor, and note the contents. 

2.	Add one line or remove one for the location to calculate flows if you want.

3.	Run the preprocessor to create a new fluxflag.prop.

.. code-block:: console

   prepare_schism input.yaml

This creates all the neceesarry files for SCHISM to run, and your edit to the **flowlines.yaml** file is what modifies the **fluxflag.prop** file.

.. note::

   More prepreprocessing documentation may be found here:
   http://baydeltaoffice.water.ca.gov/modeling/deltamodeling/models/tools/ 

Adding Observation Point Locations
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The station input file “**station.in**” used to launch *SCHISM* is how the x-,y-, and z- coordinates are associated with the station name. The z-coordinate in this example uses -1.0 m as the “default” observation depth, other depths are classified as “upper” or “lower” depending on where they are in the water column.

In the Hello SCHISM example model, there are 6 stations that have been designated prior to running the model in the “station.in” file which are distributed in the model domain:

.. _obs_sta_req:

.. figure:: /img/schism_obs_stations.png
   :alt: Hello SCHISM Input Stations
   :align: center

   *Hello SCHISM observation stations as specified by the station.in file*