Snow in the mountains is a source of water supply in our areas that we use not only for drinking but also for other household purposes. In certain areas, it accounts for more than 90 % of the water supply. Snow water equivalent is the amount of water we would obtain by melting a column of snow. Snow equivalent water is calculated to estimate the volume of water that would be produced after melting a glacier or mountain. One can use our snow water equivalent calculator for quick calculations.
What is Snow Water Equivalent?
Snow water equivalent is the amount of water available in a snowpack. It is the product of the density of the snow core and the depth of the snow core. Snow is a form of precipitation but the thing that makes it unique and difficult to work with is its response time from when it accumulates to when it produces runoff and groundwater recharge that is why we need a long time step in water balance analysis. The density of snow depends on temperature and pressure. It has a different value for different types of snow. The density of snow is different than liquid water because crystalline water (snow and ice) is interspersed with air.
Importance of SWE
SWE is important because it is a good indicator of how much water will be available when the snow melts. This is especially important in areas where snowmelt is the primary source of water for rivers and streams. The SWE can also be used to estimate the amount of water that will be available for irrigation and other purposes. There are several methods for measuring SWE, but the most common is the weighing method. This involves weighing a sample of snow, melting it, and then weighing the resulting water. The difference between the two weights is the SWE.
Snow water equivalent value depends on various factors
- Type of snow and the density of the snow.
- The length of time for which the snow is been in place.
- The temperature of the air.
- The number of contaminants and impurities present in the snow.
Calculation of Snow Water Equivalent
Snow water equivalent of a certain area can be calculated by following the simple steps
- Measure the length, width, and depth of the snowpack.
- Calculate the volume of the snowpack by multiplying the above values.
- Select the density of the snow from literature depending on the type of snow.
- Calculate the snow water equivalent by multiplying volume and density.
SWE = Volume of snow x density of snow
Old Rule of Thumb
James church began stated in his work that 10 inches of snow are equal to one inch of water.
Following is the example to calculate the snow water equivalent for a given snowpack.
Example # 1
Calculate the snow water equivalent value of fresh snow whose area is 56 inches and depth is 40 inches. The density of fresh snow is 5 %.
SWE = Volume x density
Volume = area x depth
Volume = 56 x 40
Volume = 2240
SWE = 2240 x 0.05
SWE = 112 inches
Answer; the snow water equivalent value for the given snowpack is 112 inches.
Water volume can be estimated manually using the conversion formula or you can just use our snow water equivalent calculator to get an accurate value of SWE in gallons or any desired unit of volume. Simply put the given data in the calculator and you will get the value of SWE.