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McCook Gazette
Editorial

Trees, grassland and water use as a zero-sum game

Thursday, June 16, 2011

Did J. Sterling Morton get it all wrong?

We won't go that far, but a recent report delivered to local Natural Resources Districts does seem to indicate that attempts to reinvent the prairie in the image of the father of Arbor Day's native, tree-covered Michigan are misguided.

The use of water is a zero-sum game, and consumption of precipitation by grassland and trees leaves less for crops and, more importantly for legal purposes, less to send down the Republican River to Kansas.

The Republican River Basin Water Balance Study report presented at the Middle Republican NRD Tuesday night showed just that.

Riparian forests -- wooded areas near rivers, about the only kind that exist in Southwest Nebraska -- and woodlands use more water per acre than any other land use, including crops, according to the study.

Riparian forest and woodlands use 4.26 acre feet of water a year or 51.2 inches of average annual consumption.

By comparison, irrigated corn uses 2.34 acre feet of water, or 28.1 inches of average annual consumption.

An acre-foot is the amount of water it takes to cover an acre of land one foot deep in water, or 325,851 gallons.

It shows that trees, especially those with root systems that reach deep, consume a lot of water," said Frank Kwapnioski of H20 Options Engineering LLC of Lincoln, Nebraska.

The study seemed to show a link between water consumed by trees and grass and the overall decrease in surface water, he said.

"In the 1930s, the landscape was different than it is now, which may describe the change being seen in overall surface water," he said, "though there are many factors, not just one."

The problem is, the Republican River Compact conflict, which threatens agriculture in Southwest Nebraska, was signed -- by the State of Nebraska, we must add -- with that 1930s landscape in mind, rather than modern conditions that exist following decades of conservation efforts and growth of trees and underbrush.

We enjoy trees and feel they add much to our communities. However, a new river agreement should be negotiated with modern conditions taken into account.

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  • Perhaps I misunderstand the cycle of water. I believe I was taught that although a tree does suck up some 'surface' water, it also brings back to the cycle of rain, water from much deeper, which, if not brought to the atmosphere, would not see productivity for a very very long time, as it would be trapped in the aquifer (like the Oglalla), where, eventually, springs would send a portion back to the surface for evaporation and cloud building.

    Has anyone heard of a "Rain Desert" anywhere on earth?? No? How a bout a "Rain Forest?" The trees are not there because of the water so much as the water is there because of the trees.

    Removing the trees, along the rivers would, I suppose, reduce the 'loss' of surface water, but not at 4.5 acre feet per year. From that number would need be the water that has passed the level of recycling, on its way to the aquifer. The short term savings would be improved, buerosionon, and loss of rainfall would/could be devastating on the crop production. Which the lessor evil?

    Just a thought, from a non-expert. Please give the whole Bio-painting a full, cause and affect, perusal before determining a simple fix will actually 'fix' the whole problem.

    -- Posted by Navyblue on Thu, Jun 16, 2011, at 8:06 PM

  • Rain forests exist because they receive rain. The idea that trees create more rain is like the old lie that "rain follows the plow." http://en.wikipedia.org/wiki/Rain_follows_the_plow

    -- Posted by croswind on Fri, Jun 17, 2011, at 8:49 AM

  • It does not really matter very much which type of vegetation uses the most water "on average" or during average to wet years. Our river compact compliance depends on delivering water in all years, especially during the driest years or multiple consecutive dry years. Problem is that that's exactly when ET demands the most water, so corn consumes more than usual. But research shows that many native trees reduce their water use during times of drought stress.

    No, the obvious large difference between the 1930s landscape and that of today is not the narrow ribbons of riparian woodland. Rather, it is the amazing spread of irrigation out of the valleys onto the center-pivot sprinkled uplands.

    -- Posted by arby waterdog on Fri, Jun 17, 2011, at 1:34 PM

  • The thing the writer does not tell you is that the riparian forerst occupies less than 1% of the land use while irrigation occupies 24% of the land use.

    -- Posted by GCoates on Sun, Jun 19, 2011, at 6:43 AM
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