HR: 10:20h
AN: H52B-01    [Abstracts]
TI: Estimating Groundwater Recharge in Response to Potential Future Climate Change: The Importance of Winter Temperatures
AU: Jyrkama, M I
EM: mjyrkama@uwaterloo.ca
AU: * Sykes, J F
EM: sykesj@uwaterloo.ca
AF: University of Waterloo, Department of Civil Engineering 200 University Avenue West, Waterloo, ON N2L3G1 Canada
AB: Changes in future climate will alter regional hydrologic cycles and subsequently impact the quantity and quality of regional water resources. While climate change affects surface water resources directly through changes in the major long-term climate variables such as air temperature, precipitation, and evapotranspiration, the relationship between the changing climate variables and groundwater is more complicated and poorly understood. Groundwater resources are related to climate change through the direct interaction with surface water resources, such as lakes and rivers, and indirectly through the recharge process. Therefore, quantifying the impact of climate change on groundwater resources requires not only reliable forecasting of changes in the major climatic variables, but also accurate estimation of groundwater recharge. The primary goal of this study is estimating the impact of potential future climate changes on seasonally varying groundwater recharge with an emphasis on evaluating the importance of winter temperature. Two case studies are investigated: the Grand River watershed in south-western Ontario that drains an area of nearly 7000 square kilometres into Lake Erie and a 139 square kilometre highly monitored area of the Cohansey aquifer at Toms River NJ. For both areas, the physically based hydrologic model HELP3 is used in conjunction with GIS to simulate the past conditions and future changes in evapotranspiration, potential surface runoff, and groundwater recharge rates as a result of projected changes in the regions climate. The climate change projections are based on the general predictions reported by the Intergovernmental Panel on Climate Change (IPCC) in 2001. For the Grand River Basin, forty years of daily historical weather data are used as the reference condition while for the Toms River study, the reference period is from 1970 to the present. The impact of climate change on the hydrologic cycle is modelled by perturbing the HELP3 model input parameters using predicted future changes in precipitation, temperature, and solar radiation. The changes in land use and vegetation cover over time were not considered in the study. The results of the two case studies reveal the importance of warmer winter temperatures on reducing the extent and duration of ground frost and shifting the spring melt from spring toward winter months, allowing more water to infiltrate into the ground. The historical monitoring well data and climate record for the Cohansey aquifer clearly show this effect as do the simulations for the perturbed historical weather record for the Grand River watershed. The predicted higher intensity and frequency of future precipitation will not only contribute significantly to increased surface runoff, but also results in higher evapotranspiration and groundwater recharge rates due to increased amounts of available water. Changes in the incoming solar radiation have a minimal impact on the simulated hydrologic processes.
DE: 1637 Regional climate change
DE: 1829 Groundwater hydrology
DE: 1838 Infiltration
DE: 1876 Water budgets
SC: Hydrology [H]
MN: Fall Meeting 2005