Sanna (Inn)
The Sanna at Pians - Pianner surge
Course
The Sanna arises from the confluence of Rosanna and Trisanna at Castle Wiesberg (municipality Tobadill ). The Rosanna flows from Verwall coming through the Stanzertal that Trisanna rises in the Silvretta and flows through the Paznaun. The Sanna flows first in a northerly to northeasterly, then in an easterly direction through the lower Stanzertal and flows near Landeck, in the Inn. At the Sanna are the three places Pians, Grins and Landeck. She takes in its course three major tributaries to: The Lattenbach at Pians and Mühlbach near Grins from the left and the Flath Bach at Pians from the right.
Catchment area
The natural catchment area of 727.7 km ² Sanna is. Through the derivation of many tributaries of Rosanna and Trisanna in the Silvretta reservoir and the Kops the hydrologically effective catchment area is reduced by 163.8 km ². Since this water is passed over the main European watershed of time, the effective catchment area of the Danube and Rhine can be reduced by this amount or enlarged.
The mean altitude of the catchment area is 2200 m above sea level. A., the highest point is the Southern Escape Horn with 3399 m above sea level. A. In the catchment area of Sanna there are 67 glaciers with a total area of 15.48 km ², which corresponds to a Vergletscherungsgrad of 2.1 % (as of 2002). The majority of glacier runoff is derived but in the reservoirs, only 19 glaciers remain with the flow regime of Sanna.
Water management
The average discharge at the level Landeck- Bruggen is 20.0 m³ / s, which corresponds to a runoff of 35.5 l / s · km ². The Sanna has a nivales flow regime that is dominated by the melting snow in the higher elevations of the watershed. The glaciers have only a minor impact due to the discharges. The monthly mean outflow richest month of June is 50.8 m³ / s approximately ten times the outflow poorest month of February with 5.31 m³ / s
Heavy rainfall in the catchment area and a snow line high-lying led in August 2005 to the largest ever recorded flood event with a maximum discharge of 491 m³ / s, more than twice the measured up to that maximum value. While the damage in the area of Sanna were comparatively low, it came both by Rosanna and Trisanna, as well innabwärts to massive flooding (Alpine Flood 2005 ).
Environment
The Sanna has a very good to good, in the city of Landeck a moderate ecological status. The sole is only selectively, the banks are built on long drives. The river is classified in water quality class I- II ( 2005).
White water sports
The Sanna is a gefällstarker, heavily interlocked river. Therefore for rafting and kayaking athletes of difficulty, despite the significantly lower water levels, much higher than that of the Inn. Be short hard shafts Change to a distance of six kilometers nonstop with heavy breakers and rollers, while at the same time the free flow of water is inhibited by irregularly located right in the current draw boulders and cross bar.
In 1996, the World Championships Canoe whitewater racing took place on the Sanna.