Variographic analysis of water table data from the oued-souf phreatic aquifer, northeastern part of the algerian Sahara

Phreatic aquifers present many serious problems for local public authorities, and they have done so especially for the water resources managers in Oued-Souf, Algeria, since 1980. Recently, a perturbation in piezometric level was observed in Oued-Souf. The spatial distribution of piezometric level data was analyzed by applying geostatistical methods, which provide an indication of the uncertainty of the estimation using the computer software VARIOWIN 2.2. In this paper, the evolution of the piezometric level by referring to other research campaigns was studied. Campaigns were conducted from March 1993 to April 2002. In the beginning, elementary statistics has been carried out to understand the statistical distribution and performed an analysis of variance so that two campaigns could be chosen for comparison. Geostatistics for modeling and cartography were applied. The results show that piezometric levels admit power model that the direction of groundwater flow is from south to north and that, due to the return of irrigation water (there is no drainage system), water levels increase in places like Foulia (1.35 m), northwest of Oued-Souf (1.43 m), Kouinine (4.58 m), and Ouzitene (3.01 m). The water levels also decrease in places like Guemar, Dmitha, Rhamra, and Djeldida, from between 2 and 6 m, due to excessive pumping of groundwater.