Regional differences in climate change impacts on groundwater and stream discharge in Denmark

TY - JOUR

T1 - Regional differences in climate change impacts on groundwater and stream discharge in Denmark

AU - Van Roosmalen, Lieke Petronella G

AU - Christensen, Britt S.B.

AU - Sonnenborg, Torben O.

PY - 2007

Y1 - 2007

N2 - 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 1961-1990 and 2071-2100 from a regional climate model representing the IPCC scenarios A2 and B2. A physically-based, distributed hydrological model simulates changes in groundwater head, recharge, and discharge. Precipitation, temperature, and reference evapotranspiration increase 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 dependant on the geological setting of the model area. In the Jylland area, characterized by sandy top soils and large interconnected aquifers, groundwater recharge increases 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.

AB - 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 1961-1990 and 2071-2100 from a regional climate model representing the IPCC scenarios A2 and B2. A physically-based, distributed hydrological model simulates changes in groundwater head, recharge, and discharge. Precipitation, temperature, and reference evapotranspiration increase 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 dependant on the geological setting of the model area. In the Jylland area, characterized by sandy top soils and large interconnected aquifers, groundwater recharge increases 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.

KW - Faculty of Science

KW - regional klima model

KW - grundvand

KW - climate change impacts

KW - regional climate model

KW - river discharge

KW - recharge

KW - groundwater

U2 - 10.2136/vzj2006.0093

DO - 10.2136/vzj2006.0093

M3 - Journal article

SN - 1539-1663

VL - 6

SP - 554

EP - 571

JO - Vadose Zone Journal

JF - Vadose Zone Journal

IS - 3

ER -