Frozen Groundand Snow Pack Runoff from a Ski Resort 2

[Ryb01]

Hello Everyone.

I'm currently working on calcualting runoff from a ski hill to a chalet type residential area at the bottom of the hill. The total drainage area to the residential area is approx 400ha. Land gradient of the hill is approx 25%, residential area is at a 3-5% grade, D type soils. The municipality has asked to model the snow pack conatined within the ski slopes and wooded areas to determine potential peak flow increases. Could anyone recommend any reference material or knowledge regarding snow pack calculations and or calculating runoff from ski hills?

Thank you in advance.

 

[SMIAH]

Theres an ajustement of curve number (CN) for frozen soils
Knisel and al. (1985).

If the CN (antecedent II) for unfrozen foil is less than or equal to 80, the CN for frozen foil conditions is set to 95.
When the unfrozen soil CN is greater than 80, the CN is reset to be 98 on days where the soil are frozen.

This will result in a decrease in infiltration under frozen conditions, which has been observed in numerous studies.

 

[SMIAH]

frozen soil*

 

[hydroponder]

In Minnesota we are generally asked to analyze the 10-day snow melt event of 7.2 inches. This is generally considered the 100-year event for snowmelt in MN. In HydroCAD, you can select the 'Spillway 1-day 10-day' storm type and input in your depth (7.2 inches for MN). For frozen conditions, the antecedent moisture condition (AMC) is set to 4. By setting the AMC to 4, HydroCAD will automatically adjust your normal non-frozen curve numbers accordingly. Of course, the challenge for you will be to determine the appropriate depth.

 

[Ryb01]

Thank you everyone for your valuable information. I'm not too familiar with HydroCAD or HEC-HMS but I will look into further. Does anyone have experience with modelling snow packs in SWMM? or have a sample template they would be willing to provide in SWMM? Any additional information would be greatly appreciated. Thank you in advance for your help.