Renovation of water and central heating pipelines is a very costly and time‐consuming process; therefore, a way to prioritize the limited resources between different parts of the systems is very important. The risk for corrosion damage can be assessed from the resistivity of the ground, because the processes facilitating the metal oxidation also affect the resistivity. However, galvanic resistivity mapping is time consuming and work‐intensive in paved areas. To determine the resistivity in the vicinity of pipes two different resistivity methods were applied: electrical resistivity tomography using galvanic coupling, and the logistically easier and rapid electrostatic measurements using capacitive coupling. The two methods were tested in a series of experiments undertaken in the province of Scania in southern Sweden with the aim to acquire a better knowledge about the electrical resistivity of the soil surrounding the heating and water distribution pipes, in order to better assess the corrosivity of the environment. From the experiments it is shown that the electrical resistivity tomography and electrostatic methods mostly give comparable results for the shallow investigated depths in focus here, where differences might be caused by different sensitivities and noise characteristics. In the case of both methods, it is shown, with the help of modelling of the different expected ground models including the pipes, that the pipes only influence the data in cases of pipes of very large diameters or those buried at a very shallow depth, even without any protective surface coating. The missing influence of the pipes on the data makes the methods very applicable for knowing the resistivity of the soil surrounding the pipes and thus evaluation of corrosion risk.

The semi‐arid Plio‐Quaternary aquifer of the Kairouan Plain is located in the central part of Tunisia. In this region, the main form of human activity is extensive agriculture. The few lithological logs in this area indicate that the aquifer is divided into two groundwater reservoirs separated by a confining clay layer. In the shallower groundwater reservoir, the electrical conductivity of the water is close to 1,200 mS/m, that is, 3 to 4 times higher than that of the deeper aquifer, which is currently used for irrigation. Recently, an increase in salinity has been observed, which is producing significant difficulties with irrigation. In order to determine the geometry of the confining clay layer and assess the potential connectivity between both reservoirs, time‐domain electromagnetic (TDEM) and vertical electrical soundings surveys were carried out. In the extremely conductive environment (electrical resistivities <10 Ωm) of the Sebkha Kelbia, the TDEM survey produced the first geophysical map of this near‐surface aquifer system.

Usually, in-situ electrical polarisation measurements (in geophysical prospection referred to as Induced Polarization (IP), or Spectral Induced Polarization (SIP)) have been carried out at frequencies below 1 kHz. These techniques have been used mainly for mining exploration, followed by a larger panel of environmental applications. However, in this ultra and extremely low frequency domain, the duration of each individual measurement is long: typically several tens of minutes for a single full SIP spectrum down to the mHz range. This restriction makes it unrealistic to implement high-density measurement mapping campaigns over large areas, which would otherwise be possible at higher frequencies. In the intermediate frequency range [3 kHz -3 MHz], laboratory studies of soil and rock samples have shown that they can be strongly polarized notably in the presence of clays, and this property has been confirmed by several in-situ mapping experiments using electromagnetic induction (EMI) in the time and frequency domains (FDEM and TDEM), as well as by the electrostatic method (often named Capacitive Coupled Resistivity or CCR). The present paper recalls these results

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