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In every edition of WSL's magazine DIAGONAL we present an instrument, a tool, a machine - in short an object. Apart from the presentation in the magazine, there is always a video clip of the object.


The NFI rucksack

WSL staff are currently recording data on the Swiss forest for the fifth National Forest Inventory (NFI). On the NFI sample plots, they measure the trees, describe the tree stand and assess the site conditions. They carry all the instruments and tools they need in a rucksack to the plots, which are sometimes difficult to get to. The material includes several GPS instruments, a tool for measuring tree height, and a so-called Finnish calliper. This is used to measure a tree’s diameter at a height of seven metres. Using this diameter, together with the diameter at a height of 1.3 m and the tree height, the volume of the tree can be calculated.


Bedload basket sampler

Floods in torrents frequently transport large quantities of stones and sand down with them. In the Alptal (Canton Schwyz), WSL has been measuring how much material the Erlenbach transports. When a flood event occurs, metal baskets move automatically into the stream and collect the solid material. Along with the data from the acoustic sensors, the researchers can then determine the bedload transport for different particle sizes.


Debris-flow slides

A debris flow is a fast-flowing and destructive mixture of water, fine sediments and pieces of rock. Researchers release model debris flows onto an eight-meter long slide in the mountain hydrology lab at WSL. This enables them to test the flow, impact and deposition behavior of different debris-flow mixtures.



The SnowMicroPen (Snow Micropenetrometer) was developed at SLF to measure snow-cover hardness without having to shovel snow. Such measurements allow conclusions to be drawn about the snow density and structure, and thus about the snow stratigraphy, which is an important factor in avalanche formation.


Seed kilning barrel

WSL harvests and kilns forest seed material, and operates the national seed agency, which offers seed material to forestry enterprises and tree nurseries. In a refrigerated storage room, WSL stores up to 60-year-old Norway spruce seeds from a variety of origins, as well as seed material from a further 50 tree species and shrubs.