How much water is in my Yard

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Equation / Last modified by KurtHeckman on 2018/06/01 12:58
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Titan.How much water is in my Yard

The How much water is in my Yard calculator computes how much water is in the snow in your yard, patio or roof.  YardSnow.jpg

INSTRUCTIONS: Choose your preferred units and enter the following:

  • (w) The width of the area covered with snow.
  • (l) The length of the area covered with snow.
  • (d) The depth of the snow
  • (sT) This is the snow type.  Choose one from the pull-down list.  See details on snow type below.

Liquid Water: The calculator returns the amount of liquid water contained in the snow in U.S. gallons.  However, this can be automatically converted to numerous other volume units (e.g. liters) via the pull-down menu.

Water, Rain and Snow Calculators:


My front yard is covered in snow.  i noticed this equation in the vCalc library for Snow Water Equivalent (SWE) that defines a relationship between snow and the amount of water it would melt into.

I used this SWE equation and the known density of water to calculate a factor for the snow melt water conversion;

      I also added in variables for the length and width of my yard (or for any area you want to measure) and there is the selection for 'type of snow'.  

I can now calculate how much water is in my yard if I was able to capture all the snow as it melted.

Type of snow or ice(kg/m3)
New snow50-70
Damp new snow100-200
Settled snow200-300
Depth hoar100-300
Wind packed snow350-400
Firn (granular)400-830
Very wet 700-800
Glacier ice830-917

The Math

The "how much water is in my yard" equation uses the Snow Water Equivalent (SWE) equation and the density of water to calculate the amount of snow melt water.

Snow Water Equivalent (SWE) is the product of snow depth and snow density. It can be presented in units of either kg/m2 or m:

             SWE (`(kg)/(m^2)`) = snow depth (m) x snow density (`(kg)/(m^3)`)
             SWE (m) = snow depth (m) x snow density (`(kg)/(m^3)`) / water density (`(kg)/(m^3)`)

You can calculate snow depth from SWE if you know the density of the snow.  Of course, density of snow can range anywhere from 5% when ambient air temperature is 14 F, and can range up to 20% if the temperature is 32 F.

The snow density will increase after the snowfall due to gravitational settling, packing, wind effects, melting and refreezing.

This data was found in a very cool book:     Paterson, W.S.B. 1994. The Physics of Glaciers

            The equation will use a median value for the ranges in the density value column to then calculate the (median) snow melt or amount of water this could melt into.