We present a joint inversion scheme that couples P‐wave refraction and seismic surface‐wave data for a layered subsurface. An algorithm is implemented with a damped least‐squares approach. The estimated parameters are S‐ and P‐wave velocities and layer thicknesses, while densities are assumed constant during inversion. The coupling is both geometric and physical: layer thicknesses are the same for S‐ and P‐wave velocity profiles and P‐wave velocities enter in both forward algorithms. Sensitivity analysis, performed on synthetic data, reveals that surface‐wave dispersion curves can be sensitive also to P‐wave velocity of some layers (especially for Poisson's ratio values smaller than about 0.35), allowing synergic resolution of this parameter. Applications on both synthetic and field data show that the proposed approach mitigates the hidden layer problem of seismic refraction and leads to more accurate results than individual inversions also for surface waves. Additional constraints on the objective function on a priori Poisson's ratio values allow unrealistic and not admissible VP and VS values to be avoided; such constraints were applied in one field case considering the a priori information available about water‐table depth. It is also shown that estimation of porosity can help the selection of the proper constraint on a priori Poisson's ratio.

Bathymetry and bottom sediment types of inland water basins provide meaningful information to estimate water reserves and possible connections between surface and groundwater. Waterborne geophysical surveys can be used to obtain several independent physical parameters to study the sediments. We explored the possibilities of retrieving information on both shallow and deep geological structures beneath a morainic lake by means of waterborne nonseismic methods. In this respect, we discuss simultaneous magnetic, electrical, and groundpenetrating radar (GPR) waterborne surveys on the Candia morainic lake in northerly Turin (Italy). We used waterborne GPR to obtain information on the bottom sediment and the bathymetry needed to constrain the magnetic and electrical inversions. We obtained a map of the total magnetic field (TMF) over the lake from which we computed a 2D constrained compact magnetic inversion for selected profiles, along with a laterally constrained inversion for one electrical profile. The magnetic survey detected some deep anomalous bodies within the subbottom moraine. The electrical profiles gave information on the more superficial layer of bottom sediments. We identify where the coarse morainic material outcrops from the bottom finer sediments from a correspondence between high GPR reflectivity, resistivity, and magnetic anomalies.

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