Fig. 2. Two typical time domain reflectometry (TDR) waveforms obtained with the variable volume coaxial probe (VVCP) placed in soil saturated with tap water (electrical conductivity [EC] = 0.01 dS m^–1) and with salt solution (resulting in bulk EC of 2 dS m^–1). The variables t₁ and t₂ mark the first and second reflections used for travel time analysis of the waveform. The values V₀ and V₁ are used for the calculation of EC (see text for detail).