traveltimetc change

[harper-wavra]

traveltimetc - sheet flow equations changed from old version

changed to =(0.42/SQRT(H19))(H17H16/SQRT(H18/100))^0.8 from =(0.42/SQRT(H19))(H17H16/SQRT((MAX(0.0001,H18)/100))^0.8)

[amedenblik]

Related to #56

[harper-wavra]

• [ ] surface["Overland Slope"] must be > 0 or user will receive an error
• [ ] edit the example request to not be 0 - change it to match the spreadsheet