What is nokken?
Nokk are male water spirits who play enchanted songs on the violin, luring women and children to get into lakes or streams. Not all of these spirits were necessarily malevolent; in fact, many stories exist that indicate at the very least that nokker were entirely harmless to their audience and attracted not only women and children, but men as well with their sweet songs. Nokken sings about his loneliness and his longing for salvation, which he purportedly never shall receive, as he is not "a child of God". If you brought the nokk a treat of three drops of blood, a black animal, some vodka or snus (wet snuff) dropped into the water, he would teach you his enchanting form of music.
It is difficult to describe the actual appearance of the nokk, as one of his central attributes was thought to be shapeshifting. Perhaps he did not have any true shape. He could show himself as a man playing the violin in brooks and waterfalls but also could appear to be treasure or various floating objects. Nokk are said to grow despondent if they do not have free, regular contact with a water source. (Loosely paraphrased from Wikipedia.)
Where are water flows retrieved?
Water flows are consensually scraped from The Norwegian Water Resources and Energy Directorate, Glommens og Laagens Brukseierforening, and Friends of the Lysaker catchment. Weather observations and forecasts are provided by The Norwegian Meteorological Institute.
Where to get guides for rivers?
Data on river sections, optimal water levels, and similar information is primarily based on excellent guides. If you haven't checked out these guides yet, be sure to do so — they're free! The whitewater kayaking community is deeply indebted to their author for his efforts to maintain these guides.
The printed Riverguide for Oppdal and around is also a nice source of information, but only for the Oppdal (and around) area.
How are sections graded?
Sections are graded on a scale from I to VI. I is flat moving water. VI is not considered navigable. Sections are graded based on the predominant difficulty. Hence, a sections graded to III, might have one IV rapid. Moreover, the grading reflects the technical difficulty of successfully running a rapid. It does not take into account surrounding aspects, such as whether the river runs in a canyon or not.
How are the optimal flow levels determined?
Some sections with a gauge have set thresholds for whether we consider the flow be too low, low, good, high, or very high. These thresholds are set to accommodate the average kayaker conditional on the grading of the section.
Too low — Flows are soo low that navigating the river without getting stuck on bedrock is difficult.
Low — There is sufficient water to navigate the river. Some parts might be quite shallow. Typically set to indicate whether it is worth it to take the time to go there.
Good — Indicates what is considered to be optimal flow. This is the reference for the grading of the section.
High — Rapids become more powerful. The grading of the section might increase.
Very high — Flood state. High risk of debris. Pools flush. Grading should be disregarded.
Is there an API?
Yes. All the data for Nokken is stored in the Nessie database. An API for Nessie is available at api.nokken.net.