133 Years of Rainfall in Bexar County!
by
Commissioner Tommy Adkisson
August 12, 2004

Since Bexar County administers the Flood Tax that supplements what the San Antonio River Authority, the City of San Antonio and the Army Corp of Engineers provide, a little background of rainfall in Bexar County would seem appropriate to an ongoing discussion of what we are doing about controlling it once it falls here!  Anyone that knows me knows I really appreciate the value of history.  I've enjoyed and I believe profited from knowledge of the history of man, history of government, and history of quite a few things, but history of San Antonio Rainfall?  Of course! 

If the "past is prologue" as Shakespeare says, we ignore history at our own peril.  Take a look at the San Antonio Rainfall amounts under "Critical Charts" on my website cited below and you will find some very interesting facts compiled by the National Weather Service (the "Service").  I am so very glad that this federal agency thought to track the amounts of rainfall since 1871! 

Let's see, that was when the Mayor of San Antonio was W. C. A. Thielepape, Texas was in the throes of Reconstruction, the Legislature did not meet and our Governor, Andrew Jackson Hamilton, was appointed by President Andrew Johnson!  Still, some diligent soul collected the facts on rainfall. 

Take a look.  The Service accentuates months over the one hundred and thirty years when no rain fell and when record rain fell.  What happened over the millions of years before you and I got here is left for your and my imagination. 

Recorded history however shows us that 32.92 inches is the normal amount of rain that fell annually since 1871.  It tells us that the wettest year (1973) dropped 52.28 inches of rain on us while the driest year (1917) left us with a mere 10.11 inches!  Oddly enough, the storied year of the "Flood of ‘21" only gave us 28.53 inches of rainfall for that year!

Looking beneath the surface, one might surmise that it is apparently not the volume of rain but the strategic location or concentration of its falling and the amount falling in a relatively short period of time.  This probably explains how the famed Flood of '21 with a fairly normal annual rainfall of 28.53 produced 10 feet of water in downtown San Antonio!  Some might say we did not have Olmos Dam, finished in 1927.  Neither did we have nearly the amount of flood or drainage provisions or infrastructure as we do today.  But then we also did not have today's impervious cover: rooftops, pavement and concrete! 

The maximum amount of rainfall for any given month in the 133 years of recording interestingly enough was October, 1998: 18.07 inches!

I suppose what we can all agree upon is that fighting Mother Nature is difficult if not impossible.  However, man's attempts to develop and then rectify the effects of changing the earth's landscape have consequences.  My next article on rain will attempt to capsulize what Bexar County and the community at large is doing to make for a safer experience when record or significant rainfall occurs.  

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