Recharge sensitivity to local and regional precipitation in semiarid midlatitude regions

The influence of regional, local, and total precipitation on groundwater recharge in a semiarid region is investigated through modeling. Daily precipitation data at two meteorological stations within Okanagan Basin, British Columbia, Canada, are classified into regional (similar to 60% of annual) and local (similar to 40% of annual) precipitation. The classified daily precipitation data are used as inputs to a one-dimensional unsaturated zone recharge model, HELP 3.80 D. The recharge response is calculated at the base of the similar to 1.2 m soil columns for 86 soil profiles typical of the region. Results suggest that local precipitation events contribute insignificant amounts of recharge compared to regional events. Precipitation data from global climate models that cannot simulate local events accurately may therefore still provide reasonable estimates of groundwater recharge.