Posted by: shipbright | October 12, 2009

Water and Agriculture…The Ogallala Aquifer.

When the well is dry, we know the worth of water.

Benjamin Franklin, 1746

Much of the world’s freshwater is contained and stored underground in geologic formations known as Aquifers.  The United States Geological Survey defines an aquifer as, “a geologic formation, group of formations, or part of a formation that contains sufficient saturated permeable material to yield significant quantities of water to wells and springs.”  Basically, the water percolates into underground deposits of sand or gravel, collects between the particles, and flows within the formation .

400px-Aquifer_en_svgAquifers are the source of some of the purest water on earth and not all aquifers are easily accessed because of their depth.   Furthermore, while these aquifers are renewable, they are often very slow in their recharge, or replenishment, rate.  The central concern for any aquifer is not to withdraw more than is replenished–just like your checking account at the bank. Thus, our growing global population and demand for water and production of food is increasing the amount of water being withdrawn from aquifers, but the recharge rates remain the same, eventually causing an imbalance and a depletion of the amount of water in the aquifer. To take the finance analogy one step further, once an aquifer runs dry, it won’t give out water on credit while we figure out how to recharge it.

So, on the heels of the last post about water and agriculture it would be illustrative to take one of the premier global aquifers as an example of the pressures on our freshwater natural resources.  “The Ogallala Aquifer, also known as the High Plains Aquifer, is a vast, yet shallow, underground water table aquifer located beneath the Great Plains in the United States.

ogallala_aquifer1

It covers an area of approximately 174,000 mi² (450,000 km²) in portions of the eight states of South Dakota, Nebraska, Wyoming, Colorado, Kansas, Oklahoma, New Mexico, and Texas. It was named in 1898 for its locality near the town of Ogallala, Nebraska” [wikipedia].

Here’s a primer on the Aquifer from Waterencyclopedia.com [edited for length]:  The Ogallala Aquifer occupies the High Plains of the United States, extending northward from western Texas to South Dakota. The Ogallala is the leading geologic formation in what is known as the High Plains Aquifer System. The entire system underlies about 450,000 square kilometers (174,000 square miles) of eight states…The Ogallala is composed primarily of unconsolidated, poorly sorted clay, silt, sand, and gravel with groundwater filling the spaces between grains below the water table. The Ogallala was laid down about 10 million years ago by fluvial deposition from streams that flowed eastward from the Rocky Mountains during the Pliocene epoch.  Erosion has removed the deposits between the mountains and the existing western boundary of the Ogallala, so there is no longer water recharge being received from the Rockies.

The Ogallala is an unconfined aquifer, and virtually all recharge comes from rainwater and snowmelt. As the High Plains has a semiarid climate, recharge is minimal. Recharge varies by amount of precipitation, soil type, and vegetational cover and averages less than 25 millimeters (1 inch) annually for the region as a whole. In a few areas, recharge from surface water diversions has occurred. Groundwater does flow through the High Plains Aquifer, but at an average rate of only 300 millimeters (12 inches) per day.

300px-Ogallala_saturated_thickness_1997-sattk97-v2_svgThe depth to the water table of the Ogallala Aquifer varies from actual surface discharge to over 150 meters (500 feet). Generally, the aquifer is found from 15 to 90 meters (50 to 300 feet) below the land surface. The saturated thickness also varies greatly. Although the average saturated thickness is about 60 meters (200 feet), it exceeds 300 meters (1,000 feet) in west-central Nebraska and is only one-tenth that in much of western Texas. Because both the saturated thickness and the areal extent of the Ogallala Aquifer is greater in Nebraska, the state accounts for two-thirds of the volume of Ogallala groundwater, followed by Texas and Kansas, each with about 10 percent.

The Ogallala Aquifer, whose total water storage is about equal to that of Lake Huron in the Midwest, is the single most important source of water in the High Plains region, providing nearly all the water for residential, industrial, and agricultural use. Because of widespread irrigation, farming accounts for 94 percent of the groundwater use. Irrigated agriculture forms the base of the regional economy. It supports nearly one-fifth of the wheat, corn, cotton, and cattle produced in the United States. Crops provide grains and hay for confined feeding of cattle and hogs and for dairies. The cattle feedlots support a large meatpacking industry. Without irrigation from the Ogallala Aquifer, there would be a much smaller regional population and far less economic activity.

300px-Ogallala_changes_1980-1995_svgBecause of the Ogallala, the High Plains is the leading irrigation area in the Western Hemisphere. Overall, 5.5 million hectares (nearly 13.6 million acres) are irrigated in the Ogallala region. The leading state irrigating from the Ogallala is Nebraska (46%), followed by Texas (30%) and Kansas (14%). The Ogallala Aquifer is being both depleted and polluted. Irrigation withdraws much groundwater, yet little of it is replaced by recharge. Since large-scale irrigation began in the 1940s, water levels have declined more than 30 meters (100 feet) in parts of Kansas, New Mexico, Oklahoma, and Texas. In the 1980s and 1990s, the rate of groundwater mining, or overdraft, lessened, but still averaged approximately 82 centimeters (2.7 feet) per year.

Increased efficiency in irrigation continues to slow the rate of water level decline. State governments and local water districts throughout the region have developed policies to promote groundwater conservation and slow or eliminate the expansion of irrigation. Generally, management has emphasized planned and orderly depletion, not sustainable yield [my emphasis]. Depletion results in reduced irrigation in areas with limited saturated thickness and increased energy cost in all areas as the depth to water increases.

Commentary: As you can see from the above description of one of the world’s premier aquifers the management of this water is for orderly depletion and not sustainable water management.  In other words, it’s a planned bankruptcy.

We can’t do that.  I’ll be the first one to say I am no expert on agriculture and irrigation but I do know that governments, businesses and academia are focusing serious efforts on developing new and more efficient irrigation techniques.  Techniques that the Israelis have developed and championed in the Middle East, for example.  For the Ogallala, slowing the rate of depletion buys us time but it doesn’t solve the problem.  It doesn’t address the central issue that we’re using more than is being replenished.

ag_crops_fieldWith agriculture being the greatest demand on freshwater resources we have to make technologies, like drip irrigation, economically accessible to those who grow or raise our food.  Supporting our farmers, ranchers and agriculturists is supporting ourselves.  Supporting them is not about giving them handouts, it’s about creating fiscal incentives and programs that allows them to meet our needs.

We need to think out the scenarios of the world’s breadbaskets when the aquifers, rivers, lakes, and inland seas run dry.  Look at the example of the Aral Sea:

AralSeaDriedup

Envisioning those scenarios and looking at what we have already done to ourselves ought to send a chill down our collective spines.  We need to focus our serious attention and resources on this issue as we have seen what happens in the world when economic, political or physical access to water is denied.

It’s a thirsty planet we’re on and it’s getting crowded and hotter.

no water…no civility…no civilization.

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Responses

  1. What I don’t understand is why no one (i.e. The Federal Government), has not taken action to refill the aquifer, which is already some 100+ feet below normal levels.
    We built a pipe line from Alaska to supply oil for our energy needs, How difficult could it be to build a pipeline from say Lake Superior to the northernmost edge of the aquifer in Nebraska or from Lake Michigan to Kansas or both. There is a virtually unlimited water supply that comes from glacial melt but instead of tapping into it we just let it all go out to sea via Niagara Falls. I can’t believe that none of the great minds we have in this great country have not considered this relatively easy solution to this potentially catastrophic problem. What I don’t understand is why no one (i.e. The Federal Government), has not taken action to refill the aquifer, which is already some 100+ feet below normal levels.
    We built a pipe line from Alaska to supply oil for our energy needs, How difficult could it be to build a pipeline from say Lake Superior to the northernmost edge of the aquifer in Nebraska or from Lake Michigan to Kansas or both. There is a virtually unlimited water supply that comes from glacial melt but instead of tapping into it we just let it all go out to sea via Niagara Falls. I can’t believe that none of the great minds we have in this great country have not considered this relatively easy solution to this potentially catastrophic problem.

  2. [...] Bright is a blog concerned with fresh water issues, and the post on October 12, 2009 (read it here) features a great description of the current situation, including what they call the “planned [...]

  3. Hi Ship,

    Great Post…

    We need to get you together with Carl Ganter, Co-founder of Circle of Blue. http://www.circleofblue.org/waternews/ We met him at Greg Mort’s (Port Clyde). You would definitely find a lot of common ground.

    George and Holly


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