Värmdö municipality, in the archipelago of Stockholm, has one of Sweden’s fastest growing populations and is a popular location for tourism and summer houses. This puts a lot of pressure on groundwater reservoirs and will likely be even more strained in the future as the climate continues to heat up due to anthropogenic activities. The aim of this study is to investigate the use of groundwater resources on the island of Ingarö, today and in a changing climate. The goal was also to identify the behaviour of the groundwater reservoir under different extraction rates. A model was constructed using MODFLOW, a software developed and maintained by the U.S. Geological Survey. The results show that for the present-day scenario with the current extraction rate there is a surplus of recharge leaving the reservoir. Moreover, three groundwater divides could be identified in the reservoir which can prove useful when examining the movement of contaminants. The result also indicated that an extraction rate of 105% of current extractions could be possible without any artificial infiltration. At an extraction rate of 110%, one well struggled with keeping up with demand for water. As the extraction rate increased further the results were deemed as inconclusive. For these scenarios, model domain required to be extended further east due to a constant head boundary condition acting as an infinite source of water in these cases.
Keywords: GMS, MODFLOW, GIS, RCP, climate change, archipelago, esker, glaciofluvial soil
Dahlberg, M. (2020). Modelling of aquifer on Ingarö island : A Steady-State model. Master's thesis. KTH, School of Architecture and the Built Environment.