Table 3 Major characteristics observed by the field data and calibration results

Rate and magnitude of temperature increase at shallow depth in shallow monitoring wells (Figs. 8, 9)

Model overestimates initial rate of temperature increase. Long-term magnitude of temperature increase matched in NK-1, NL-4, and NL-10. Slightly underestimates temperature increase in NL-02 and NL-07. Overestimates temperature increase in NL-08 and NL-09

Temperature increase measured at shallow outflows along lake (Fig. 10)

Model reproduces temperature increase at Eidvik but underestimates seasonal fluctuations. Slightly underestimates rate and magnitude of temperature increase at Markagja and strongly underestimates magnitude of temperature increase at Varmagja

Temperature–depth relations in shallow monitoring wells (Fig. 11)

Model reproduces temperature reversals in NL-10 resulting from shallow outflow along lava flow. Warmer isothermal zone between 50 and 150 m in NL-12 is not present in model results

Tracer return time in shallow monitoring wells and natural outflows (Fig. 17)

Rapid returns in NK-1 and NK-2 reproduced. Model predicts later tracer return than observed in natural outflows

Shape of the tracer return curve (Fig. 17)

Model reproduces narrow peak in tracer return curve in nearby monitoring wells. Model prediction of long-tail (higher tracer concentrations at later times) in natural outflows not observed in measured data