Using geostatistical method to delimit a water bearing formations

Morocco is a country which has semi-arid to arid climate. rainfall is irregular in time and space. surface water undergoes very large fluctuations according to variation of the hydraulicity during all the year. the groundwater resources play a very important role in supplying water to rural populations and irrigation. the purpose of this study was the evaluation of geostatistical methods for delimitation of water-bearing formations in outita region. thus a geophysical survey of 52 geoelectric soundings ves was performed with a mesh of 500 m using the schlumberger array with current electrodes spacings between 200 and 3000 m. geostatistical tools were used to quantify the spatial correlation between apparent resistivity data. semivariograms were obtained using a classical matheron semivariogram estimator and fitted to the obtained experimental semivariograms. we have selected those with the best fit in terms of sum of squared residuals (ssr). the structural analysis is based on the study of oil drillings. it shows that the jarassic and neogene formations are affected by normal and reverse faults delimiting horsts and grabens. the qualitative interpretation of the kriged resistivity maps allows defining resistivity contrast; consequently we have delimited water-bearing formations. the resistivity maps confirmed the graben structure,obtained from the structural analysis,with nw se direction. models of the geology were successfully obtained from geostatistical method,which help mapping the water-bearing formations and the estimations of groundwater resources.