To verify the accuracy of quantifying the soil water evaporation using
the C–G model, we compared the actual evaporation losses with the
calculated evaporation losses (Fig. 8). We observed that the calculated
evaporation was close to the actual evaporation, and the variation trend
followed by the soil water evaporation intensity with depth was
approximately the same. During the entire test period, the relative
error of the evaporation loss calculated based on δ18O
was 13%, and the relative error of the evaporation loss calculated
based on δ2H was 34%. The use of
δ18O to quantify the soil water evaporation loss
resulted in a 21% greater accuracy than that resulting from
δ2H. However, the approach involving the use of
isotopes had a lower evaporation loss, which may have been caused by the
approximate treatment of the values of various parameters in the model
calculation. Considering that there were some unavoidable sources of
errors, such as the absolute error caused by the instrument itself, in
field experiments, it is feasible to use stable hydrogen and oxygen
isotopes combined with a modified C–G model to quantify the evaporation
of bare soil under
continuous-evaporation
conditions.
Fig. 8 Comparison of the actual evaporation loss and calculated
evaporation loss at different soil
depths and different periods from May 13, 2018 to June 27, 2019 (based
on δ18O and δD
isotopes).