The Helgeå Watershed

The Helgeå Watershed is a demo area in Sweden.

The watershed is characterized by a mosaic landscape where forests, farmlands, villages and towns alternate. The main river is the Helgeå river that gives the name to the watershed. It is about 200 kilometres long and flows into the Baltic Sea. The course of the Helgeå river runs from the north sparsely populated to the south densely populated region through different kinds of nature types.

About 55 percent of the watershed is covered by forest and 5 percent by water and totally more than 5 500 kilometres of watercourses run through the Helgeå watershed landscape. Forests are unevenly distributed, concentrated mainly in the northern two-thirds of the watershed. The total standing volume is about 44 Mm3 mainly represented by coniferous species like Norway spruce and Scots pine.

Broadleaved forests are dominated by birch species with beech and oak species playing an important role regarding biodiversity. Swamp forest and wetlands characterize the whole watershed.

Helgeå watershed houses generally high natural values with respect to both the aquatic environment and species. Parts of the bottom of the main river Helgeå are characterized by unique geological formations in form of undulating structure. Seven freshwater mussel species were found in the Helgeå water system, included the thick shelled river mussel (Unio crassus) and the freshwater pearl mussel (Margaritifera margaritifera) both classified as Natura-2000 species.

The Swedish Environmental Protection Agency has designated several rivers and lakes within the watershed as of regional and national interest thanks to the presence of species like the river water crowfoot (Ranunculus fluitans), the sheatfish (Silurus glanis) and the European crayfish (Astacus astacus), some of them are unique for Sweden.

Climate data

Statistics from the near weather station in Osby showing the normal average of precipitation (millimetres) and temperature (°C), 1961-1991.

Precipitation (millimetres)

Station: Osby
Period: 1961-1991

Jan – 60,8
Feb – 38,1
Mar – 48,1
Apr – 43,6
May – 44,1
Jun – 36,6
Jul – 76,6
Aug – 67,4
Sep – 71,0
Oct – 64,5
Nov – 68,7
Dec – 64,9
Year – 711,5

Temperature (degrees celsius)

Station: Osby
Period: 1961–1991

Jan – -2,2
Feb – -2,1
Mar – 0,6
Apr – 5,0
May – 10,5
Jun – 14,4
Jul – 15,5
Aug – 14,9
Sep – 11,3
Oct – 7,4
Nov – 2,8
Dec – -0,7
Year – 6,5

  • Last Updated: 4/2/2024