Have you ever wondered about the different types of flood messages?
So far this year, NVCA has issued two flood messages. Both of our issued messages have been Watershed Condition Statements: Water Safety, which means that we don't anticipate any major flooding, however there will be heavy rain or snowmelt.
NVCA issues three different levels of flood messaging: Watershed Condition Statements (Water Safety Statement and Flood Outlook Statement), Flood Watches, and Flood Warnings.
But how do we know when these messages should go out in the winter?
To determine flood conditions in our watershed during the winter, we look at snow pack (how dense the snow is) through snow surveys, forecast to see how much precipitation is coming, and look at the flow of our rivers (the volume of water passing through the river at cubic meters per second).
NVCA's flood team uses a Snow Tube Sampler (pictured above) to measure and weigh the snow in snow surveys. This helps them to determine how much potential water there is for flooding.
When a snow survey is done, our team visits the same nine sites across the watershed. Some of these sites they've been measuring for 50 years!
Snow surveys are able to determine snow/water equivalent, which is how many millimeters of rain would be equal to the amount of snow if it were to melt. This measures density, as heavily packed snow will weigh more and contribute a larger amount of water runoff.
To learn more about flood forecasting, click here.
