Regional Differences in Climate Change Impacts on Groundwater and Stream Discharge in Denmark

Abstract

Regional impact studies of the effects of future climate change are necessary because projected changes in meteorological variables vary regionally, and different hydrological systems can react in various ways to the same changes. In this study the effects of climate change on groundwater recharge, storage, and discharge to streams are compared in two geologically and climatologically different regions in Denmark. Outputs are used for the periods 1961 to 1990 and 2071 to 2100 from a regional climate model representing the Intergovernmental Panel on Climate Change (IPCC) scenarios A2 and B2. A physically based, distributed hydrological model simulates changes in groundwater head, recharge, and discharge. Precipitation, temperature, and reference evapotranspiration increased for both the A2 and B2 scenarios. This results in a significant increase in mean annual net precipitation, but with decreased values in the summer months. The magnitude of the hydrological response to the simulated climate change is highly dependent on the geological setting of the model area. In the Jylland area, characterized by sandy top soils and large interconnected aquifers, groundwater recharge increased significantly, resulting in higher groundwater levels and increasing groundwater–river interaction. On Sjaelland, where the topsoil is dominated by low‐permeability soils and the aquifers are protected by thick clay layers of regional extent, only minor changes in groundwater levels are predicted. The primary effect in this area is the change in stream discharge, caused by changes in drain flow and overland flow, with up to 50% increase in winter and 50% decrease in summer. This study shows the added value of studying different climate scenarios and hydrological systems, so that the simulated effects can be compared both qualitatively and quantitatively.

Effect of Unsaturated Flow Model Conceptualization on the Dynamic Response of an Integrated Distributed Hydrological Model

“…The parameter values for the evapotranspiration and interception models were adopted from previous studies in Denmark (Van Roosmalen et al, 2007).…”

Linking Climate Change and Groundwater

“…The complexity of approaches for obtaining the climate data series appears to have increased in recent years, ranging from the use of global averages (Loaiciga et al 1996;Zektser and Loaiciga 1993) to the use of regional "bulk" projections (Allen et al 2004;Brouyere et al 2004;Vaccaro 1992;Yusoff et al 2002) to the direct application of downscaled climate data (Jyrkama and Sykes 2007;Scibek and Allen 2006b;Scibek et al 2007;Serrat-Capdevila et al 2007;Toews and Allen 2009) to the use of regional climate models (Rivard et al 2008;van Roosmalen et al 2007van Roosmalen et al , 2009). Some of the early efforts to assess potential hydrologic impacts were reviewed by Gleik (1986).…”

“…Tietjen et al (2009) made a case for at least two soil layers in a soil-vegetation model that simulated soil-water dynamics under different climatic conditions. Others have applied relatively complex, spatially distributed subsurface models and coupled surface-groundwater models (Goderniaux et al 2009;Hunt et al 2013;van Roosmalen et al 2007van Roosmalen et al , 2009). …”

Assessing the influence of groundwater and land surface scheme in the modelling of land surface–atmosphere feedbacks over the FIFE area in Kansas, USA

“…As a result hydrological impact studies of climate change have 42 generally been carried out by simply forcing hydrological models with output from climate models (e.g. 43 Graham et al 2007;van Roosmalen et al 2007). In this type of approach, feedback from the terrestrial part 44 of the hydrological cycle to the atmosphere is neglected, which may result in significant errors (Seneviratne 45 et al 2010).…”