Hur hänger det ihop? : En hydrologisk detaljstudie av ytvattenkonnektivitet mellan sjöar och vattendrag i Västerbottens län

Sammanfattning: Surface water hydrology is a deeply studied subject, yet there are barely any studies concerning surface water connectivity, neither micro- nor macro scale. With the explosive development of GIS over the past decade, tools for measuring and analysing rivers and lakes are inumerable. Light detection and ranging (LiDAR) has also seen tremendous improvements over the years. This study uses high resolution digital elevation models and georeferenced aereal photographs to carry out a detailed GIS-analysis of river-lake connectivity in three catchments in Västerbotten, Sweden: Bjurbäcken, Hjuksån and Gargån. Hjuksån is located beneath the highest coast line (HCL) wheras the other catchments are located above this line. A second pupose of the study is also to test if lake size varies above and below HCL. Lakes were digitized at 1:2000 scale and the rivers were digitized and categorized in Strahler stream order using tools in ArcGIS Pro. The data from the study was compared to data from the Swedish Meteorological and Hydrological Institute (SMHI), as well as data from international studies. The results show a surface water connection of 71,4% for Bjurbäcken, 62% for Hjuksån and 73,1% for Gargån. Comparing this data to data from SMHI results in a lowering of the surface water connection by 20 percentage points för Bjurbäcken, 30,3 for Hjuksån and 8,2 for Gargån. Lake size was tested between the catchments using an ANOVA, yielding a significant difference between Hjuksån and Bjurbäcken as well as Hjuksån and Gargån, backing up the hypothesis that HCL affects lake size.