River Water Irrigation

The National Weather Service operates the Advanced Hydrologic Prediction Service which monitors river levels across the US.  The Suwannee River is a mile from my house.  In the second largest recorded flood of the Suwannee, the river came all the way up to my garage.  One inch higher, it would have entered the garage.  During the summer I tend to keep an eye on the level close to home.   I've seen the river nearly dry up, with just a trickle running through the sculpted limestone bottom.  When it is that low the flow rate is as low as 100 cubic feet per minute.  Today the river is at 61 feet above sea level with a flow rate of over 3000 cubic feet per second.  Flood stage is 77 feet.  My garage is at 85.5 feet

The Suwannee is a blackwater river.  The dark color is a result of the tannins from hundreds of square miles of oak trees in the surrounding laural forest, as well as drainage from the Okeefenokee Swamp.  It's black.  Stand in it up to your waist, you probably won't see your feet.  The tannins make the river acidic with a pH between 5 and 6, depending on the weather.  There are whitewater and clearwater rivers that have a more neutral pH.  In the US alone there are 250,000 rivers.  Some of these empty into other rivers.  Some empty into intercoastal waterways, bays, and directly into the ocean.  

This river water is fresh water, on the surface, which is continually floating out to sea.  97.5% of the Earth's water is in the oceans...salt.  2.5% of the Earth's water is fresh, with 70% of that trapped in the ice caps of Antarctica and Greenland.  Most of the rest is in soil moisture or trapped so far underground as to be unrecoverable.  Less than 1/100th of that 2.5% fresh water is accessible to humans in lakes, rivers, and underground reservoirs such as the Ogalalla.  Fresh water is really quite a rare thing.  

The California Drought of the last few years is still going on.  See the US Drought Monitor for current conditions.  Surface reservoirs are drying up,  rivers are running dry, people are spray painting their lawns green...it's a booming business.  Farmers and growers are pumping water out of the ground to such an extent that much of the Central Valley is subsiding.  The ground is several feet lower than it was 5 years ago.  While California was entering a drought, Texas and the lower midwest was going through a massive drought.  Farmers had to sell off their cattle herds because the price of hay had gone through the roof.  Hay was being purchased near me in north Florida to be transported to Texas, and diesel was $5/gallon.  The price of beef went down with the spike in product availability, then shot back up while the ranchers replenish their herds.  

I don't think Global Warming is the appropriate term.  The warming is so gradual that a short lived species such as humans don't notice the temperature climb.  We are frogs in a pot of water on the stove.  Carl Sagan used the term Climate Destabilization back in the 70s to describe the changes in weather patterns that would result from a warming or cooling of the planet.  Anyone who has been gardening for a decade will tell you the weather patterns have changed.  The Azaleas are blooming 2 weeks earlier than they used to.  It's really frigged up the Azalea Festival over at Stephen Foster Park.  Frost coming very early, very late, or not at all.  I saw a frost in June '09 back in New York.  We can expect bigger storms or an absence of big storms.  We'll see torrential rains along with extended drought.  What was dependable becomes undependable.  With a world population of over 7 billion, we really need dependable food production.  

Getting back to the Suwannee River...that flow rate of 3000 cubic feet per second is impressive when arithmetic is added.  I'll only use 1000 cubic feet, allowing the rest to flow as normal out to sea to maintain the intertidal and estuary ecosystems.
    1000 cubic feet per second
    x 7.48 gallons/cubic foot
    x 60 seconds per minute
    x 60 minutes/hour
    x 24 hours/day
    = 646,272,000 gallons of fresh water per day

This is an interesting figure.  Looking at the population clock, the US population is 321,734,900 as of 7:29 AM 9/13/2015.  The Suwannee River, or any river from which could be drawn 1000 cubic feet of water per second, would provide enough fresh water to supply every person in the US with 2 gallons of drinking water-a day's supply.  In the grand scheme, the Suwannee is a tiny body of water, perhaps 100 feet wide.  For comparison, the Mississippi is nearly a mile wide in most places and a whole lot deeper.

Here's the What If

What if, instead of letting all this fresh water flow into the ocean, we could harvest a portion of it, impound it in a reservoir, and use it to irrigate our crops during times of drought?  

One of the aspects brought to agriculture by the Green Revolution is irrigation.  Currently, some 55 Million acres of crops are irrrigated in the US.  That's out of 900 Million acres being used for crops and rangeland.  Only 6% of the land being used for agriculture in the US is irrigated.  Primarily these are high value crops: vegetables, orchards, vineyards, and some grains.  To offer the equivalent of 1 inch of rain across just a fraction of this area, say, 1 million acres, requires 27,152,400,000 (27 Billion) gallons of water.  The pumps sucking the excess 1000 cubic feet of flow from the little Suwannee River would need to be running continuously for 42 days to draw that much volume.

In a drought, that 1 million acres will need an inch of rain at least every week for the duration of the growing season.  I'm going to say 12 weeks is needed to raise a crop.  Now that 1 million acres needs 324 billion gallons.  For a late season crop, double that figure.  648 billion gallons.  The pumps on the Suwannee would have to run continuously for 1000 days.  That's 2.7 years to serve 1 million acres for 6 months.  A multi year drought like the one going on in California will take many rivers many years.  

Where do we keep all that water?  
Storing the water in a reservoir is impractical.  27 billions of gallons takes up a lot of volume...3,609,625,668 cubic feet.  At a depth of 500 feet, the area of a reservoir needed to hold this volume would be 165 acres.  It would last a week.  To handle the demand of millions of acres for full production through a multi year drought, the volume of water required begins to compare to Lake Superior.  Storing this sort of volume would take half the state of Utah.  We could do it.  It would take decades.  But...JESUS.

Storing the water to be doled out later does not really make a whole lot of sense because all we are doing is adding reservoirs.  Once we tap those reservoirs the operating procedures will tend to focus on maintaining a desired level within the reservoir.  This means balancing the incoming water with the outgoing water.  If we can keep the balance, we are moving water from point A to point B.  That's really the whole objective.  Parking it for a while offers no advantage.  Volume of storage is not the goal.  Rate of flow is what we need.

Let's have a look at what would be needed to handle the flow from the Suwannee.  
1000 cubic feet of water per second.  That sort of volume would take a pipeline 18 feet across flowing at a rate of 1 foot per second.  That's only 3/4 of a mile per hour.  Building a network of 18 foot wide pipeline across the US would be daunting to say the least.  Then there are the pumps, lift stations to get the water over mountains, the power requirements for the pumps, maintenance on the entire pipeline, bridges, accesss to the land on which to build all this, and designing it such that wildlife can cross under or over it unimpeded.  

Pipelines have some problems.  What happens when one pump fails?  The pump upline is still adding pressure.  It will need to be shut down, as will every upline pump until the problem is resolved.  What if the pipeline breaks.  An 18 foot diameter pipe, cracked open by an earthquake is going to spill a river across someone's backyard or wash away a town.  Perhaps a pipeline is not the way to go.

This is a file from the Wikimedia Commons. Information from its description page there is found at: https://en.wikipedia.org/wiki/File:Second_Los_Angeles_Aqueduct_Cascades,_Sylmar.jpgWilliam Mulholland built the Los Angeles Aqueduct system with open lined channels and covered conduit.  He built 2 sections with a 12 foot diameter.  The first with a length of 233 miles, and can handle a flow rate of 422 cubic feet per second.  The 2nd section has a length of 137 miles and a flow rate of 290 cubic feet per second.  This is a flow rate that is comparable to the volume I've discussed with the Suwannee River.  What I'm suggesting is scaling the system up a couple of notches.

We don't have to build an entire network of aqueducts.  In the US we already have a vast system in place to hold and move water: the rivers themselves.  We've already got vast reservoirs: the lakes.  The challenge, then, is to use these existing waterways to transfer water.  Take it from the Hudson to the Susquehanna to the Ohio which flows to the Mississippi.  Draw it out from the Arkansas to feed the Colorado which serves the LA Aqueduct.  

Without a doubt, this idea is way out there.  But we have problems we need to solve and wild ideas may be what it takes.  Right now, we are draining underground aquifers faster than they can be recharged.  Shallow wells are running dry.  Eventually, the deepest wells will run dry spelling the end of irrigation unless a source is tapped.  We've got the water.  It's just in the wrong spot.  If we had the ability to move the excess from where it is to where it needs to be, we've got a chance to keep up with our unquenchable thirst.  

We've made our bed and we've got to sleep in it.  Climate Destabilization is our foreseeable future.  We've got the technology: pumps, renewable energy, canals, aqueducts, dams, and locks.  If we don't address the situation the reason is not because it is impossible but rather because we are negligent.  Prudence will determine if we face our challenges and implement solutions to them before we are negatively impacted.  All too often the political forces in our nation only deal with problems of the day, leaving tomorrow's problems for tomorrow's politicians.  Of course by then it's too late for mitigation.  The resulting bailout will be far more expensive and likely too little too late to make a difference.  We need to look at this issue now and begin planning and building.  Failure to act now will mean a failure of crops later, when our population is larger and dependency on irrigation is such that a failure of crops will result in an abrupt decline of that population.

We have a choice.
1] Address Climate Destabilization now.
or
2] Address Population Destabilization tomorrow.

This is not a simple solution.  It comes with it's own problems.  How do we power the pumps for such an enourmous volume of water to be moved hundreds and thousands of miles?   Pumping out more CO2 by burning fossil fuels to power the pumps only exacerbates the climate issue which is the problem in the first place.  Renewable energy is possible but nobody wants a windmill to spoil their view of soon to be brown pastures.  We'll have to remove litter and debris from the water before it clogs up the pumps.  We'll have to keep fish, frogs, eels, snakes, beaver, and kids out of the pumping areas.  Australia shows what invasive species can do.  Then there's the pH issue of blackwater.  If we start pumping acidic water into a neutral river we'll disrupt the ecosystem forever.  Changing the acidity of a body of water and churning it up with a sudden flow increase will stir up all those sediments and start leaching dioxins, mercury, PCBs and toxic wastes from a century of industrialization and nonexistent pollution controls.  I wonder if we have not already frigged up the planet to the point the damage can not be repaired.

Perhaps there is a way to have our cake and eat it too.  Long aqueducts could be put to commercial use in aquaponics.  Raise fish in some of these canals.  Downstream of the fish, set up an algae farm to make use of the nutrients added to the water by the fish waste.  Pelletize it, feed the algae back to the fish.  Make biofuels with the algae.  Use the algae as a soil amendment. 

Geoengineering the planet is not a long term solution.  As a tool for mitigating the affects of future drought, it offers some relief.  The long term solution is to return to the sustainable methods used by mother nature. 

  • Sequester carbon by incorporating hummus and organic matter into the soil to increase water holding capacity
  • Reduce soil compaction so water can permeate the soil rather than run off
  • Use mulch to protect the soil and preserve the moisture in it
  • Increase the number of farms, relocalize food production and promote the diversity of products on each farm
    California is not the only place lettuce can grow
  • Grow food where the water is
  • Grow food instead of lawns

The Green Revolution has increased our numbers to the point we have become dependent on Green Revolution methods.  We need time to wean our civilization off the chemical, mechanical, industrial teat.  We need time to repair the damage we have done to our world.  We need time to redevelop the agriculture systems we once had and look for ways to improve what we do so as to be less dependent on ideas which seemed good but have proven to be self destructive.

 

Lake Powell's receding waters show risk of U.S. "megadrought"