Mitigation measures at the Hálslón Reservoir
Hálslón is the intake reservoir for the Kárahnjúkar Hydropower Station. Extensive monitoring is carried out in the area every year, including the collection of data on erosion and sand encroachment. The Soil Conservation Service of Iceland (SCSI) has overseen assessments of the area since 2013.
Measuring stations were set up at Kringilsá area to monitor and measure aeolian deposition. Erosion is measured annually and is regularly detected on the Kringilsá coastline. High water levels and difficult weather conditions, during the autumn of 2018, exacerbated the situation and erosion reached the protected area in Kringilsá. Mitigation measures were introduced in 2019 when Landsvirkjun installed a 180 metre erosion and encroachment defence at the north end of Kringilsá. The measures were designed to prevent further erosion during high water level periods in the reservoir. The defences will be extended by 200 metres to the west (alongside the river channel) in the summer of 2020.
The 180 erosion and encroachment defence installed by Landsvirkjun at the north end of the Kringilsá, by Hálslón, last summer.
The Soil Conservation Service of Iceland (SCSI) also monitors aeolian deposition, vegetation protection and land reclamation at Hálslón Reservoir. The results show that aeolian deposition is still active and land reclamation projects will therefore continue. Aeolian deposition distribution varies between years, due to various factors and achieving a correct balance between mitigation and distribution can therefore be challenging. Consequently, monitoring will continue in accordance with the conditions of the utilisation licence. A clean-up of deposits was carried out alongside land reclamation projects in the area.
Existing vegetation was reinforced on the east bank of the Hálslón reservoir to better capture windborne sand. 68.7 tonnes of fertiliser was applied to 484 hectares of land.
Monitoring during the operational phase
Landsvirkjun has constructed three new power stations over the past six years: Búðarháls Hydropower Station in 2014, Þeistareykir Geothermal Power Station in 2017 and the Búrfell II Hydropower Station in 2018. The areas potentially impacted by these stations are closely monitored to assess if and how they are affected.
Reservoir Biota in Sporðöldulón
Sporðöldulón is the intake reservoir for the Búðarháls Hydropower Station which began operations in 2014.
Limnology research, carried out between 2014 and 2018, has provided comprehensive data on the development of the ecosystem in the newly formed reservoir.
The results are comparable to those previously obtained in other new reservoirs. However, the mineral composition of the reservoir is comparable to older reservoirs and local habitats. Minerals are frequently released from underlying soil in reservoirs, stimulating the growth of organisms and fish fertility. However, this has not occurred in Sporðöldulón, which suggests that the underlying soil is nutrient poor.
Research indicates that the Arctic char rapidly became the dominant fish species in the reservoir which indicates that juveniles have access to a sufficient food supply.
Water table fluctuations in the lagoon are relatively small and littoral zones are therefore likely to thrive, providing more food sources for fish. This could contribute to positive growth conditions in the reservoir, especially for the brown trout.
Limnology research was conducted in collaboration with the Marine and Freshwater Research Institute (MFRI). Ongoing research is being considered.