Hobølelva River: erosion, landslide & eutrophication

National Id
Site name
Hobølelva River
The Kråkstadelva catchment, as case study area, is located within the Hobølelva watershed, located ca. 30km S-SE of Oslo, Norway. The area of the Kråkstadelva catchment is approximately 51 km2. Agricultural land covers ca. 43% of the catchment (22km2) and it is dominated by cereal production. Forest covers ca. 45% of the catchment. Heavy clay soils dominate in the area (up to 80% of clay content). Mean annual temperature is 5.3°C and average annual precipitation is c.a. 864 mm. Floods of varied magnitude occur frequently in the catchment, typically during spring snow melt and autumn rainstorms. The main challenge in the area is water quality (incl. high phosphorus pollution) and soil erosion (incl. riverbank erosion and quick-clay landslides). There is already high focus on environmental mitigation measures, for example reduced tillage (no tillage in autumn), buffer zones, grass-covered water ways, constructed wetlands and the use of catch-crops.

OPTAIN project will support the case study team in identifying new land management strategies, including the best combination and allocation of measures in the catchment as well as implementing new (combinations of) measures, in order to improve water retention in the soil and the landscape and as a result reduce the risk of flooding, and improve water quality downstream.
The in-depth description of the case study
RBD code
Data provider
Climate zone
cool temperate moist
Mean annual rainfall
600 - 900 mm
Mean rainfall
Annual precip. (1993-2004): 651-1305 mm.yr-1(avg. 864 mm.yr -1)
Mean rainfall unit
Average temperature
Mean temp.: 5.3°C (annual), -4.8°C (Jan/Feb), 16.1°C (July).
Mean runoff
4.7 m3.s
Remarks runoff imperviousness
Avg. water discharge: ca. 4.7 m3.s (max: 102 m 3.s).
Case Study Info
Light or indepth?
Average slope range
Elevation range: 25 - 346 m a.s.l.
Vegetation class
In the North: mainly forested with Pre-Cambrian bedrock. The land use is 79% forest, 16% agriculture and 5% water areas.
Monitoring impacts effects
Public consultation
Contractural arrangements
Design contractual arrangement
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Design consultation activity
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Design land use change
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Financing mechanism
Success factor(s)
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Policy description
Local involvement has been extensive since around 1990 as catchment has been used as a study site in many projects, e.g., EU FP7 Refresh, EuroHarp, H2020 Recare). NIBIO has arranged many workshops with stakeholders of this catchment:
- Farmers and land owners;
- Water boards: local (for the catchment) and regional (for the river basin of Glomma);
- Municipalities;
- Boaters, canoes (mainly in the lake), local communities;
- Drinking water supply company (MOVAR);
- Environmentalists (f.ex., SABIMA);
- Hunting and fishing associations;
- Tourist association (Turistforeningen);etc.
Part of wider plan
Policy target
Target purpose
Erosion Control
Peak-flow reduction
Pollutants Removal
Policy pressure
Pressure directive Relevant pressure
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Policy wider plan
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