A sequential modelling approach to assess groundwater-surface water resources in a snow dominated region of Finland

摘要

Methodology was developed to estimate surface water-groundwater interactions in a changing climate in cold, snow-dominated regions and tested on an unconfined esker aquifer in northern Finland. The Watershed Simulation and Forecasting System (WSFS) model was used to simulate surface water levels. A coupled heat and mass transfer model for soil-plant-atmosphere systems (CoupModel) was used to simulate recharge. The CoupModel is able to simulate water flow through frozen soil. The simulated surface water level and recharge data were linked to the Groundwater Modelling System (GMS) version 6.5, and the three-dimensional groundwater flow model MODFLOW was used to study the impact of climate variability on groundwater levels and groundwater-surface water interactions. In addition, under A1B climate change scenario changes in aquifer storage and groundwater-surface water interactions were studied through the end of the 21st century. Recharge was shown to be sensitive to changes in soil frost and hence modelling approaches should include a soil frost component to account for the impact of frost on hydraulic conductivity. Under A1B climate change scenario study, groundwater recharge is projected to increase in winter months due to increase in snowmelt and decrease in soil frost depth. The spring snowmelt peak in late spring will decrease. This will reduce aquifer storage in early spring, increasing the vulnerability to summer droughts.