Request for help with the Hydrus 1D model simulation under evaporative conditions

[Hydraus_1d_RD]

Dear Hydrus-1D community
I hope my email finds you doing well. Presently, I’m using Hydrus-1D to simulate snowmelt effect on soil water conditions. My soil profile is just 1m thick and I have depth integrated observations for 0-10 cm and 10-30 cm depths below ground surface. My models show that once soil surface becomes too dry (relative saturation close to zero in the surface node; attached figure), soil evaporation shuts off and I see an “elbow” effect in the modeled vol. water content (VWC). This elbow effect does not appear in the observation time series which shows gradual change in VWC. I tried changing the hcritA value from 100,000 cm (default value) to 1e007 cm to ensure that soil evaporation does not shut off, but it does not help. Would you please let me know if you have any suggestions? Thank you!
Sincerely,
Ravindra