| Summary: | Many valuable ecosystems such as springs, wetlands, lakes and rivers depend on the presence of groundwater. These ecosystems, known as groundwater dependent ecosystems (GDEs), are biodiversity hotpots and provide important habitats for many endangered species. In recent decades, groundwater over-abstraction, contamination and climate change have put serious pressure on groundwater resources and groundwater-dependent ecosystems. This has shifted water management towards fully-integrated approach in which groundwater, surface water bodies and dependent ecosystems are treated as one management unit. The current EU legislation and the corresponding Finnish laws require assessment of the impacts of various land uses and groundwater abstraction to GDEs. The role of groundwater in GDEs is not, however, in many cases thoroughly understood. For this reason, groundwater-surface water (GW-SW) interactions and their dynamics need further investigation. Integrated groundwater-surface water modelling is a unique method to study connections between surface water and groundwater, and thus it is a potential tool for evaluation of various anthropogenic or climatic effects on GDEs. The aim of this thesis was to examine the performance of fully-integrated physically-based GW-SW modelling to simulate groundwater dependent ecosystems in a case study of the Kälväsvaara esker aquifer located in Northern Finland. The target was to create a model of the geologically complex esker and its adjacent areas that captures all type of GDEs present in the area i.e. fens, kettle hole lakes, streams and springs without their prior definition to the model. The study investigated how the model should be scaled and what information is needed to replicate the studied GDEs. For this purpose, a simple model was built using the fully-integrated physically-based GW-SW code HydroGeoSphere. The model was run in steady-state and it was calibrated manually by the try-and-error method. The model did not include the forestry ditch systems and it assumed ...
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