Monday, November 7, 2011

A Man With One Watch...

How many rain gauges does one person need?


Good question, eh?  We are currently comparing five.  Yes, really.

Why?

Well... The amount of rain we get during the rainy season matters to us, since it helps us anticipate how much water we can expect our well to produce during the following Summer and Fall.

In the picture above you can see the yellow plastic one that we have been using for about 19 years. It is starting to degrade due to constant UV exposure over the years, so it will only last so much longer.  In addition, it's only good to 5" rain before it overflows.  Believe it or not we get storm systems that dump more than that on us in 24 or 48 hours regularly, and that makes it inconvenient to deal with on occasion.

My wife bought the 8" rain gauge (with the decorative butterfly) on the right some time back in the hopes that it would give us a better reading on things, but the first few rains it saw - a couple last season and the first two this season - caused us to suspect it is wildly inaccurate.  It regularly read twice what the yellow gauge showed, which caused me to start researching these things.

Eventually I settled on the other three gauges:

The one in the middle is a wedge shape, capable of measuring 6" of rain, with (apparently) high accuracy.  However, accuracy drops as the amount of rain being measured in one shot goes up.

The 6" gauge with bronze numbers is from weather.com, and while it doesn't look any more accurate than the old yellow gauge, the actual accuracy remains to be seen.

And finally the large cylinder on the left is the official gauge that every weather reporting station in the country uses.  It is capable of measuring 12" of rain, snow, or hail with (apparent) great accuracy, but it is harder to read if the total amount is over 1".  A funnel directs rainfall into an interior cylinder, which overflows into the outer cylinder.  The inner cylinder measures amounts up to 1" - easy to read down to 0.01" amounts - but you have to pour out the inner cylinder after reading it, pour the overflow into it, read, add to the total, and repeat until the outer cylinder is empty.  So it is accurate, but not simple to use in a bigger storm.

Anyway, none of these is especially expensive, so I am testing them all, right next to each other, until I know which one(s) we like the most.  Then I will get rid of the others and reduce the set.

Yes, I am insane.  Yes, I am a data nut.  But the only way to know what is going on is to have data, and unless all five gauges are wildly off, I will know in another few weeks which ones I like and why.  I'll provide a detailed report - with numbers - and links to suppliers at that time.

2 comments:

  1. Craig had two electronic ones on the roof. When they replaced the roof the rain gauges came down. They are now in the closet. Someday he will put them back up.

    I use the open palm method. Put out my open palm and if it gets wet it is raining or a big bird just few over.

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  2. None of the electronic ones I looked at seemed to be particularly accurate, and they all depended on batteries, which I hate. So manual it is for us.

    As for sticking out your hand, I totally get that, but it doesn't help with knowing how much rain fell this year vs last, and from that (and previous data) starting to plan for how much water we'll have to truck in, if any.

    Besides, I like numbers. :)

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