The previous examples have shown how the seismic and acoustic methods have contributed to describe a near surface aquifer at different scales. The geophysical measurements have been done on the Hydrogeological Experimental Site of the University of Poitiers The aquifer studied, 20 to 130 m in depth, consists of tight karstic carbonates.
The different geophysical methods are:

•  3D surface seismic method,
•  Well seismic methods : ambient noise measurements and Vertical Seismic Profiles (VSP) with a hydrophone,
•  Acoustic method: Full waveform acoustic logging.

The high resolution 3D seismic block revealed three high-porosity, presumably-water-productive, layers, at depths of 35-40, 85-87 and 110-115 m. The 85-87 m-depth layer is the most porous one, with bodies of porosity higher than 30% that represent the karstic part of the reservoir.

We show how well data can be used to detect karstic bodies and flows, thanks to selected signal processing tools. The figure shows the distribution of karstic bodies in the 80 to 90 m depth interval and the localisation of the wells used to illustrate the procedure of flow detection.