When the baseline lowers …
It doesn’t happen over night.
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| Daytime over the Sonoran Desert. Somewhere down there is the San Pedro River, s seen from the Huachuca Mountains (photo credit goes to Wikipedia) |
In the case of hydrologic changes it happens over years and decades and even then the downward shift can be subtle to see. That’s where high quality data comes in handy. Don’t listen to old timer accounts. Actually, listen to them, too. But for every worthwhile memory there is an outcry of backwards thinking proclaiming how it was back in the day (after it was already altered) was how it always was going back to the beginning of time.
Can downward trends be reversed?
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| Before (left) and after (right) hydrographs of the San Pedro River. Can you see the noticeable drop in “groundwater-fed” spring baseflow in modern times? Modern times has seen the river flow lower during the summer monsoon season, too. |
Sometimes I look at hydrographs and wonder what’s in store for the years ahead. Other times I wish I could have been there back before modern times settled in.
Still, and regardless, I’m looking forward to just seeing it again.
It and I still have time.
