On average, 10 inches of freshly fallen snow melt down to 1 inch of liquid water. using this 10 to 1 ratio, the water equivalent depth of 45 cm of fresh snow is about cm.

Hello

The ratio between depth of snow and depth of water is 10:1. So, if we use 45 cm as depth of snow, the proportion to write is

where x is the depth of equivalent water. From the proportion we get
cm.