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Are we forgetting about the drought already?

The Grass is Greener

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POSTED: September 29, 2012 5:00 p.m.

I have about decided that the most prevalent attribute of the average human is an exceedingly short memory.

We are getting some rain here on the Georgia coast, and I am starting to hear complaints instead of thanks for the rain. It is Friday, Aug. 24, as I write this, and Tropical Storm Isaac still is south of Haiti. If I could steer it, I would track it over Oklahoma or central Georgia. But here on the coast, we seem to have broken the back of the drought.

At this time last year, the Brunswick area was 14.57 inches in the negative evapo-transpiration demand, but this year we are 1.82 inches of water to the good. That’s a swing of more than 16 inches in moisture. Last year at this time, Bryan County was almost 6 inches below its ET demand, while this year we are 2.4 above the line.

How quickly we forget. The tree farms are not tinder dry. The Spartina alternaflora in the marshes are turning the Day-Glo lime color that just flashes into your brain when you see it. Don’t let it fool you into thinking things are back to normal. We are recovering, that’s for sure, but getting back to where we were before all this started is going to take some time.

Last week, a resident complained about his dogwood tree showing drought symptoms. Small twigs had died back, and the leaves were brown and crunchy at the tips.

“Yessir, that’s probably drought injury.”

“But it’s been raining!”

“Yes, for the last couple weeks it has, but back in March and April when these leaves were produced, we were in the drought.
These twigs didn’t die in the last couple weeks; you just noticed them now because the rain came back, the temperatures fell and you came out from the air-conditioning.”

The return of rain is not like resetting a circuit breaker in your home. Biological systems do not reset instantaneously. Trees go through up to nine different steps to protect themselves in the face of drought. It can take up to two years for trees to reverse the systems’ shut-down and get back to the growth patterns exhibited before the drought. If trees do not have enough energy on hand to fund the restarts, the tree will die.

Often, trees killed by a drought do not die during the drought, but die up to two years after the drought ends. People forget about the drought and do not make the mental connection between the injury caused to the tree by the drought that ended more than a year earlier, but the evidence is there in the tree if you know how to read it.

The ET rate is not the whole story. The subsurface surficial aquifers need to be recharged. Eventually, the recharged freshwater will displace the saltwater that encroached during the drought. Until then, trees at the edges of marshes still will have their roots awash in seawater.

It will take many long, slow rains that exceed the ET demand before enough rainwater is collected to push out the saltwater. Then, what is left will be a layer of brackish water that will persist until more rainwater added to the surficial aquifer flushes the brackish water down and out. The models based on the 2004 tsunami that hit Malaysia suggest it could take as long as four years of “normal” rainfall to re-establish equilibrium.

Yes, the rain, thankfully, is back. Yes, we need more, especially the slow overnight rains that soak in. We are looking for base flow to increase the stream flow, not flash flooding. And while we are doing better, the central U.S. and central Georgia still need more rain.

We have an embarrassment of riches right now when it comes to rain. Give thanks for our blessings and pray for those same boons for our brothers and sisters to the west.

Don Gardner is the UGA agricultural extension agent for Glynn County, serving South Bryan.

 

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