Quantifying the impacts of climate change on groundwater in an unconfined aquifer that is strongly influenced by surface water
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| Authors: | Scibek, J; Allen, DM; Whitfield, PH |
| Year: | 2008 |
| Journal: | 288: 79-98 Article Link (DOI) |
| Title: | Quantifying the impacts of climate change on groundwater in an unconfined aquifer that is strongly influenced by surface water |
| Abstract: | A three-dimensional transient groundwater flow model, implemented in MODFLOW, is used to quantify the impacts of climate change on groundwater in an unconfined aquifer with demonstrated strong connection to surface water (Kettle and Granby Rivers). The Grand Forks aquifer is located in a semi-arid region of south-central British Columbia, Canada. Distributed recharge is modelled using HELP, driven by the LARS-WG stochastic weather generator, and stage-discharge curves for rivers are modelled using BRANCH and calibrated to historical data. For recharge modelling, three year-long climate scenarios were run, each representing one typical year in the present, and future (2020s and 2050s), by perturbing the historical weather according to the downscaled CGCM1 global climate model results. By the 2050s the largest increase in recharge relative to present occurs in late spring, by a factor of three or more, a 50% increase in summer months in most areas of the aquifer, a 10-25% increase in autumn, and a reduction in recharge in winter. CGCM1 downscaling was also used to predict basin-scale runoff for the Kettle River. Future climate scenarios suggest a shift in the hydrograph peak to an earlier date, although the peak flow remains the same, and baseflow level is lower and of longer duration. Groundwater levels near the river floodplain are predicted to be higher earlier in the year due to an earlier onset of peak flow, but considerably lower during the summer months. Away from rivers, groundwater levels increase slightly due to the predicted increase in recharge. |
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