Browsing by Author "Suoknuuti, Rudi-Matti Ilmari"

Arctic and sub-Arctic areas have significant amounts of carbon dioxide and methane stored in the sediments which can affect the climate change. The role of groundwater in the carbon cycle in the northern regions is not well known. The processes related to the groundwater cycle depend on the structure and composition of the sediment, which in turn are determined by the way the sediment is formed.  In this study, the sedimentary structures and the hydrogeological properties of the Haaralamminkangas groundwater system was investigated. The aim was also to obtain more thorough knowledge on the geological processes that have formed the sedimentary structures of the area. Geophysical survey, drilling data, grain size analysis, and water sample analyzes were used as research methods. A sedimentary structure interpretation and 3D model were created from the data. In addition, a conceptual hydrogeological model was produced, which means information about the presence of groundwater in the area, the hydraulic connections of different parts of the groundwatersystem, and how groundwater interacts with surface waters. The 3D model will later serve in the study of the connection between the role of groundwater and the carbon cycle.  The sediments of the area was found to consist of Late Weichelian glacial sediments, fine-grained basin sediments, valley delta sand deposits, sandy gravels of the braded river system, and fine-grained flood sediments. The deposits have been formed in the following main events: Late-Weichelian glacial sedimentary processes, rapid accumulation of a sediment load on the bottom of the river valley and fluvial processes.  In the study, previously unknown information about the thickness of the sedimentary structures in the study area was clarified. Local gravel layers and a possible buried esker system wich was observed in the study may have an effect on groundwater flow. The ground water system was found to extend beyond its present boundaries and a buried bedrock in the middle of the area divides the aquifer into separate parts, where the surface waters from Puukkosuo end up in. Oulankajoki was found to be seeping into the aquifer. The modeling of the change in the height of the Oulankajoki water level showed that the effect of the spring floods is directed towards the areas of Haaralamminranta and Kouruniitty.