Implementation of technical snow production and grooming. Slopes are tagged in a provided 2D grid (same geolocalization as the DEM) where each pixel either has its slope number or nodata. Then different snow production priorities (1, 2, 3 etc) are available and can be attributed to the individual ski slopes. The number of priorities is unlimited, their relative order has no special meaning but it is not possible to have gaps in the numbering when defining the properties of the priorities (see below for the configuration keys).Please also keep in mind that during the ski season, snow is only produced when the slopes are closed to the public.

This module works hand in hand with the Snowpack TechSnow module, so it also uses the configuration keys defined in Snowpack::TechSnow to control the grooming.

Then, it relies on the following configuration keys, all in the [TechSnow] section:

SNOW_PRODUCTION: if set to true, enables this module (default: false);
SKIRUNS_FILE: the grid where all the pixels are tagged either with their slope number or nodata;
SLOPE_CONDITIONS: CSV file that gives the properties of each slope
SEASON_OPENING: Ski resort opening dates of the skiing season
SEASON_CLOSING: Ski resort ending dates of the skiing season
SLOPE_OPEN: at what local time do the slopes open to the public?
SLOPE_CLOSED: at what local time do the slopes close to the public?
MAX_SNOWGUN_WATER: max l/s that a snogun can provide

For each snow production priority, the following keys are defined (unlimited number of priorities but please, no gaps in the numbering!):

PRIO#::start_prod: snow production starting date
PRIO#::end_prod: date of the end of snow production
PRIO#::start_aim: Snow production aim in snow height [m] until ski resort opening (factor x snow_prod_min)
PRIO#::end_aim: Snow production aim in snow height [m] until ski resort ending (factor x snow_prod_min)
PRIO#::gun_operation: Percentage of snow gun operation [%]

The slope conditions file is a CSV file (the '#' or ';' characters are used to comment a line or part of it) that contains the following: the slope number, the slope area, the number of snow guns, its priority, the minimum snow height and wetbulb threshold temperature that should be present on the slope. For example:

#slope_number  nr_snowguns     priority        minimum_hs      wetbulb_threshold
#[-]           [-]             [-]             [m]             [°C]
1              10              1               0.6             -2.0

Author: Mathias Bavay, Pirmin Ebner and others