Changes of the hydroclimatic regime in the basin of the Wadi Mina (Northwest Algeria)
A change in rainfall will likely cause a change in the availability of water resources, and impacts on the human population should be important. Water resources are also subject to anthropogenic pressure that continues to grow: change of land use, dam construction, and groundwater withdrawals. The catchment basin of Wadi Mina, around 6,000 km2, located in northwest Algeria and tributary of the Wadi Cheliff, experiences a significant spatial and temporal variability of rainfall and discharges. The regionalization of the annual rainfall for this basin was conducted using data from 26 rainfall stations with 77 years of observations (1930-2007). Using statistical tests for detecting breaks in time series, we showed a decrease of 19-20% in annual rainfall over the Wadi Mina basin, mostly around 1976, and a break in time series of monthly and annual discharges at five gauging stations, starting in the mid-1970s and continuing until the 1980s. Over the whole studied discharge time series, we detected a decrease for all months, but it is mainly during the months of February, March and April, i.e., the end of the humid season, that they are the most significant. During recent years, no trend has been observed. At this scale, rainfall actually decreases significantly and steeply since 1960. Climate change currently affecting the Mediterranean is likely to have important consequences on the hydrological regimes of coastal rivers.