ANALYSES STATISTIQUE ET GEOSTATISTIQUE DE LA FRACTURATION EXTRAITE DE L’IMAGERIE ASAR ENVISAT DU SUD-EST DE LA CÔTE D’IVOIRE

Abstract

The fracturing contributes incontestably to the formation of aquifer in crystalline and cristallophyllien bedrock. Its characterization is therefore inescapable for a better knowledge of fractured aquifers.

The aim of this study is to characterize the fracturing of the southeast of Côte d'Ivoire through statistical and geostatistical methods from ASAR ENVISAT pictures. This fracturing map constitutes the important numerical support from which statistical and geostatistical processing are made.

Fractures statistical analysis showed some heterogeneity of the fracturing.It also proved that  most abundant fractures oriented (N120-130, N110-120, N150-160) are longest. The lengths of fractures are better adjusted to the power law while spacings of fractures are satisfactorily adjusted to the exponential law.

Geostatistical analysis showed that the variograms of fracturing are better adjusted to exponential model. Global fracturing variogram and N-S family fracturing variogram are structured. They are characterized by a reach, a sill and a nugget effect. The fracturing density in accumulated lengths is therefore similar to a regionalized variable. The major fracturing variogram shows a pure nugget effect. The nugget effect is due to the combined result of micro-regionalization and measurement error.