Impacts of Future Climate Change and Baltic Sea Level Rise on Groundwater Recharge, Groundwater Levels, and Surface Leakage in the Hanko Aquifer in Southern Finland

Abstract

Abstract:The impact of climate change and Baltic Sea level rise on groundwater resources in a shallow, unconfined, low-lying coastal aquifer in Hanko, southern Finland, was assessed using the UZF1 model package coupled with the three-dimensional groundwater flow model MODFLOW to simulate flow from the unsaturated zone through the aquifer. The snow and PET models were used to calculate the surface water availability for infiltration from the precipitation data used in UZF1. Infiltration rate, flow in the unsaturated zone and groundwater recharge were then simulated using UZF1. The simulation data from climate and sea level rise scenarios were compared with present data. The results indicated changes in recharge pattern during 2071-2100, with recharge occurring earlier in winter and early spring. The seasonal impacts of climate change on groundwater recharge were more significant, with surface overflow resulting in flooding during winter and early spring and drought during summer. Rising sea level would cause some parts of the aquifer to be under sea level, compromising groundwater quality due to intrusion of sea water. This, together with increased groundwater recharge, would raise groundwater levels and consequently contribute more surface leakage and potential flooding in the low-lying aquifer. OPEN ACCESSWater 2014, 6 3672

Comparison of the AVI, modified SINTACS and GALDIT vulnerability methods under future climate-change scenarios for a shallow low-lying coastal aquifer in southern Finland

“…The simulated groundwater levels under mean and dry (summer) climate conditions at present are shown in Fig. 3 (Luoma and Okkonen 2014). The water table varies between 2 and 10 m below the ground surface in the inland area, and is less than 2 m below the ground surface in the coastal area, where groundwater discharges into the Baltic Sea.…”

“…This study applied the outcomes of Luoma and Okkonen (2014) to demonstrate the impacts of climate variability and climate change on aquifer vulnerability. In addition, hydrogeochemical data, as well as field investigation and monitoring data, including the temperature, water level and electrical conductivity (EC) of groundwater, were used to confirm the degree of seawater intrusion and validate the vulnerable areas of the coastal Hanko aquifer.…”

“…Luoma and Okkonen 2014;Luoma et al 2013;Oude Essink 1999Barlow 2003;Pulido-Leboeuf 2004;Oude Essink et al 2010;Rasmussen et al 2013;Ferguson and Gleeson 2012;Ataie-Ashtiani et al 2013). These events will presumably be accelerated by the changing climate, including changes in precipitation, temperature and groundwater recharge, as well as sea-level rise and an increasing frequency of storm surges (IPCC 2000(IPCC , 2007Nicholls et al 2007).…”

“…Referring to Luoma and Okkonen (2014), a rise in the sea level due to global climate change would cause some parts of the Hanko aquifer to be below the sea level, compromising groundwater quality. This, together with the predicted increase in precipitation, would increase groundwater recharge and raise the water table, consequently contributing to the potential deterioration of groundwater quality or potential flooding in the low-lying aquifer area.…”

“…The results of a previous assessment of climate change impacts on the Hanko aquifer by Luoma and Okkonen (2014) were used to provide the inputs for three index models, the AVI, the modified version of SINTACS and GALDIT, and the results from the models were compared. The numerical approaches could be useful tools to predict contaminant transport in both space and time in the coastal aquifers.…”