| Abstract/Description or Keywords |
The relations between groundwater level fluctuations and past climatic variations are explored using available data from the provincial observation well network, climate data and hydrometric data from the two major hydro-climatic zones of British Columbia. The majority of these well records start in the late 1970s or 1980s, providing only 20 to 30 years of record at most, and only a few of these wells monitor aquifers in “pristine” areas that reflect natural variability; the others have been influenced by human activity. Mean monthly groundwater levels were used to manually classify the wells into rainfall- and snowmelt-dominated seasonal cycles. Temporal trends of groundwater levels and a simple recharge measure were calculated using the non-parametric Spearman’s rank correlation coefficient over a common period from 1976–1999. This period was selected to coincide with the positive phase of the Pacific Decadal Oscillation (PDO) so as to eliminate the potential impact a shift in the PDO might have on groundwater levels and recharge trends. Overall, late summer groundwater levels appear to have lowered across the province. Trends in recharge were more variable with both positive and negative trends. However, most of the trend results were non-significant. This assessment was complicated by the varied nature of the climate in different parts of the province, which determines the hydrologic regime (pluvial, nival, glacierized, mixed), the complexity of the groundwater system as it relates to the connection between groundwater and surface water, and the remote sources of many rivers in the mountainous regions of the province. |
