The impact of climate change on groundwater resources in northwestern Algeria

Algeria lies in one of the most vulnerable regions facing climate change impacts during the twenty-first century. Northwestern Algeria has experienced a persistent decline in annual rainfall associated with the significant increase in temperature during the twentieth century. This variability has been accentuated since the 1980s and has had a significant impact on water resources. The primary motto of the current study is to measure the impact of climate change on groundwater resources using time series of rainfall and runoff data measured in the Tafna Basin (7245 km2) of Algeria. The application of meteorological drought indices and statistical test of Pettitt shows that a rainfall regime modification occurred around the seventies. This modification reveals a decrease of rainfall between 8.21 and 38.85% according to the stations, with an average of 17.85%. The average recession coefficients obtained by Maillet’s exponential model varies between 8.90.10 and 17.06.10−2 day−1 either side of 1987, with an average increase of 45.45% and highlight a much faster drainage of the aquifers supplying the baseflow after 1987. A shortening of 1 to 11 days with an average of 6 days of the duration of the recession after 1987 was highlighted. The average water volumes mobilized by the aquifers fluctuated between 11.38 and 3.62 hm3 before and after 1987, with an average decrease of − 69.06%. These results show a decrease in the water volumes mobilized by the aquifers after 1987 and suggest a considerable decline of groundwater resources under the influence of climate change.