The N’fis basin located in Tensift region center of Morocco characterized by semi-arid climate, with an area of 2,855 km², in which 60% exceeds an altitude of 1500m. Water resources and exactly groundwater resources were overexploited in N’fis basin and agriculture sector is the most consummate. Water is the key element of socio-economic development.
Analysis of the spatial and temporal variations of hydro-climatic series and their trends shows that during the study period (1960-2010) rainfall series, flows and piezometric levels have a downward trend. While temperatures are on an upward trend. And dry years in recent decades are more frequent than wet years.
The piezometric level data were subjected to trend (Mann-Kendall), homogeneity (Pettitt rupture test) and linear regression tests. Significant trends were observed. Taking into account the α value of 5% for the N'Fis 3849/53 piezometer (p < 0.0001), -22.96% for Agafay 3595/53 (p < 0.0001) -6.38% for Tamaslohet 2715/53 (p < 0.0001). 18.42% and for Guemassa 3834/53 (p < 0.0001) 11.38%. On the other hand, the statistical breaks observed for the piezometric levels Agafay, N'Fis, Tamaslohet and Guemassa, (respectively in 2009, 2009, 2006 and 2007) were not all identified in the rainfall series. This means that the evolution of groundwater level in the aquifer also depends on factors other than precipitation.
The present study has as a purpose to study and to determine the exact effect of extreme hydrologic situations (drought and floods) on the piezometric level of the aquifer of N’fis- Haouz takes into account the other parameters mainly the water exploration for socio- economic issues. The study concerns the 30 last years.
Key words: Groundwater, Climate change impact, Statistical test.