Disappearing Rio Grande

The problem with jetty jacks is they work exactly as intended. 

These contraptions — three steel beams welded together and laced with wire — slow floodwaters, causing them to drop the sediment they carry and causing the floodplain along the river to build up. They are also placed to direct the water back to the main channel, which then gets cut deeper with the increased flows.   

Add a dam to control floods and the floodplain stops getting flooded.  The entire ecosystem changes, i.e., the cottonwoods are not being replaced. They are dying out.   

“They worked like a charm,” said Ariane Pinson, climate science specialist for the Army Corps of Engineers. “Now it’s not what we want. … If we want anything that resembles a portion of that system, we need to have the peak flows to support that.”  

Basically, if we want a river that functions as such and not as a ditch, the floods have to be restored.  

What we want is a question at the center of Pinson’s work.  

The Rio Grande is changing.  By the end of the century climate models predict its average flows will be a third less than what they are now.  Pinson and I spent a couple hours exploring the cottonwood bosque around the Rio Grande Nature Center, so she could show me what she was talking about.  

More than just a lower water volume, how that water comes is going to change as well, Pinson explained.  Snow pack will be smaller and melt faster; summer monsoons will  probably increase. 

Pinson studied the speed of climate change at the end of the last ice age.  She loves looking at how the mud from ancient lakes dried out and then blew away to become sand dunes.   

 As fascinating as that transition is, it was not easy for the plant and animal species that were dependent on the lakes.  The Southwest, and specifically the Rio Grande Valley, is facing another major transition.  

Pinson said that outside of Alaska, the Southwest is going to face the biggest negative impacts from climate change.  

“We have to know what our priorities are,” Pinson said. “Not everyone is going to be able to do what they currently do with the water.  As a community, we have to decide what that means.”  

By comparison, the jetty jacks are an easy issue to deal with.  The floodplains are now so high and dry they are becoming fire hazards. The jetty jacks, which are very similar to the ones used at Normandy, are excellent at stopping fire trucks and there is a move to start removing them.  

In the meantime, channels have been cut through the floodplain that will get flooded with even the smallest of spring floods and provide habitats similar to the old floodplains.   

It’s basically a very small version of the old Rio Grande.

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