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While the size and long residence times of many groundwater systems provides a buffering function to short-term climatic variability, many groundwater systems are potentially vulnerable to the direct and indirect effects of climate change on recharge.Climate change affects surface water resources at the localscale directly through changes in the major long-term climate variables such as air temperature, precipitation, solar radiation, wind speed, relative humidity and the resulting evapotranspiration.Groundwater resources are related to climate change through the direct interaction with surfacewater resources, and indirectly through the recharge process.Therefore,quantifying the impact of climate change on the quantity and quality of groundwater resources requires not only reliable forecasting of changes in the major climatic variables, but also accurate estimation of groundwater recharge and discharge.Estimating the renewable flux (i.e.,sustainable limit) of the hydrologic system in both its present and projected future state is the prerequisite for groundwater management.The impact on groundwater of a changing climate is investigated at a site in Toms River New Jersey for the approximately 45 year period from October 1971 to April 2014.Temporally and spatially varying groundwater recharge to the phreatic aquifer is estimated using the hydrologic model HELP3.Data for the analysis includes the land-use/land-class (LULC), soil characteristics and daily meteorological records of precipitation, maximum daily temperature and minimum daily temperature.The aquifer response to recharge was monitored using continuous loggers and manual measurements at observation wells.MODFLOW was used to model transient groundwater flow.Among other metrics that were investigated, the relationship between the temporal change in recharge and water table elevation can be illustrated in a plot of the cumulative monthly recharge minus the average recharge for the period of analysis.Positive slopes in the plot indicate periods with recharge excess while negative slopes indicate periods of recharge deficit.For the Toms River site, from approximately 1996 to 1998, the recharge was generally above average resulting in the observed rise in the water table from 1996 to 1998.From 1998 to 2002, recharge tended to be less than average.Resulting in a decline of the water table to a low observed in 2002.A significant rise in the water table in 2010 can also be explained by recharge excess and recharge deficits.At the Toms River site, the high water table events occur on a cycle of approximately 12 years with peaks in 1974, 1985, 1998 and 2010.A twelve month forward moving average of the monthly average recharge can also identify periods of recharge excess as compared to periods with a recharge deficit.The analysis indicates that the 12 month average recharge peaked in 1973, 1984, 1997, 2003 and 2009.High water table levels occurred at some time in the year following these dates.The analysis of the Toms River data set supports the hypothesis that rather than single rainfall events, periods of either recharge excess (a "rainy" season) or periods of recharge deficit (a "dry" season) are required to significantly perturb the water table elevation.This hypothesis is also supported by the fact that the hurricanes Irene (August 2011) and Sandy (October 2012) that directly hit the Toms River area had little to no impact on water table levels.The study illustrates that the statistics for the integrated climate measure of recharge are not stationary from year-to-year with long term changes in climate being superimposed onto the very noisy measure.