| Title | The Groundwater in the Mývatn Area: Influence of Geothermal Utilization at Námfjall and Origin of the Warm Groundwater Component |
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| Authors | Magnús ÓLAFSSON, Þráinn FRIÐRIKSSON, Þórófur H. HAFSTAÐ, Sigríður Sif GYLFADÓTTIR, Finnbogi ÓSKARSSON, Halldór ÁRMANNSSON |
| Year | 2015 |
| Conference | World Geothermal Congress |
| Keywords | Námafjall, Bjarnarflag, Krafla, Iceland, groundwater, geothermal system, monitoring, geochemistry |
| Abstract | The Námafjall high temperature field in North Iceland has one of longest histories of utilizing geothermal fluid in Iceland. The first wells were drilled in the early fifties for mining sulphur from the geothermal steam. In 1963 drilling started to provide steam for a diatomite plant and a 3 MW backpressure turbine in Bjarnarflag. Later a central heating system for the Reykjahlíð village and nearby farms was constructed and in 2004 the Mývatn Nature Baths opened using hot geothermal water. The geothermal area is situated only few km east of Lake Mývatn, which is a protected area by law. Lake Mývatn is known worldwide for its rich fauna of water birds, especially ducks. Landsvirkjun, the National Power Company of Iceland, owns and operates the power station in Bjarnarflag and the high temperature wells. In order to study the possible influence of the geothermal water from separation stations and wells (effluent water), Landsvirkjun has undertaken an extensive programme to study the possible influence, and also to study the origin of the thermal part of the groundwater flowing to Lake Mývatn. At present, the effluent water is disposed of on the surface and mixes with local groundwater. The nearby Krafla power station also disposes a part of its effluent water on the surface into the same groundwater stream. Water samples for chemical analyses are collected from a number of locations twice a year. For the last ten years arsenic (As) and aluminium (Al) have been used as the main natural tracers to monitor the possible influence. The results for arsenic show that its concentration in the groundwater east of Lake Mývatn is below the Environmental limit I ( less than 0,004 mg/L) and most often below the detection limit ( less than 0,00005 mg/L). The results of the monitoring are annually reported to Landsvirkjun and the Environment Agency of Iceland. |