Collecting the data for the Twin watersheds site begins well before the snow melts. In fact that is an important fact to calculate: How much snow collected during the winter at the site.

Here Dale and Bill drive across the field and measure the amount of snow on the field at predetermined spots identified by stakes in the ground in a grid pattern.

At four sites Dale and Bill stop and collect a snow core to determine the density of the snow. This is calculated using the depth of the snow that they measured, and the weight (mass) of water that the snow sample has when melted. Above, they drive the sampling pipe into the snow down to the ground.

They then push the snow and dirt into a sampling container (really an ice cream pail). Bill has invented a pushing rod to push all the sample into the pail. (below).

The sample is then capped so none is spilled.

Bill takes the sample to the lab and weighs the whole container. Then he dries the sample to drive off the water. He weighs the soil that is left and the container. The difference between the two weights is the amount of water that was in the snow core sample.. They have measured the depth of the snow, and so they can then exptrapolate the sample to the rest of the field. Then they can relate the amount of flow through the weir to the amount of snow on the watershed.

http://www.deerwood.mb.ca/march02.html