Fig. 2. Thermal breakthrough curves.

Water temperature at in- (a) and outflow (b) and rock temperatures recorded in the middle of fracture 1 (c), fracture 3 (d), fracture 6 (e), and fracture 7 (f) for a flow rate of 7.9 × 10⁻⁶ m³/s during the experiment and the numerical simulation. Difference between best-fit simulations and experimental data is less than 1 °C for the vast majority of the recorded 126 TBTC (Supplementary Figs. 2 to 22) besides few exceptions.