Kansas Study Reports

Converting Irrigated Land to Grass and Trees can Result in Less Water in the Stream

Conservation Practices Are Cause of Most Stream Flow Declines

Kansas State Scientist, James Koelliker, says 60% to 80% of the stream flow depletion in western Kansas is caused by conservation practices such as terraces, minimum till, and retention ponds.  While the study is watershed specific, almost identical conditions exist in Nebraska.  In fact, Koelliker has tested his model on the Republican River Basin, including the Nebraska portion.

Koelliker has created a table and formula that allow one to calculate the effect on stream flow based on location and type of crop or vegetation.  The table shows 44 different types of crop or range conditions for various Kansas communities. 

According to the Koelliker study, CRP results in much lower rates of runoff than does irrigated ground.  His example formula shows that converting land from irrigated ground to CRP land will result in less water in the stream.  

His data will also allow one to calculate the effect on aquifer recharge based on the type of land management program.

The Koelliker study shows that conservation practices in NW Kansas have reduced the amount of water flowing into streams and reservoirs due to flood events by as much as 50%.  He compares precipitation events in 1951-2 to similar events in 1993-4, and shows that terraces and retention ponds have dramatically reduced the expected runoff.  

This increased retention of water on the land where the precipitation fell has resulted in more water being available to plants.  According to the USDA, this retained water is responsible for 40% of the increase in yields that have been seen in dry land wheat crops since the 1930’s.  The other 60% of the increase has been the result of genetic improvements.

His report states that conservation practices have become widespread and are existent on most of the farmed land. These government mandated programs and monitoring of each field are designed to reduce erosion and floods.   They have been very successful and, in the western portion of Kansas, are the cause of 60% to 80% of the reduction in stream flow.  Any attempt to increase stream flow must find a way to balance erosion control with the needs of the stream.

There is a lot of detailed information in the report.  Reprinted with permission.  Effects of Agriculture on Water Yield in Kansas.  James Koelliker PhD, Professor and Head of Department of Biological and Agricultural Engineering, Kansas State University.

Link to scanned report.  Posted with permission.

Effects of Agriculture on Water Yield in Kansas

Reassignment of the Effects of Conservation to Groundwater (Framing the Innocent)

The way the Model calculates compliance is to do two runs of the system.  One is with all ground water pumping off and the other with all ground water pumping turned on.  The difference between the two is considered the amount of consumptive use caused by groundwater pumping.  However, there are several major events that have happened between the "pumping off" and the "pumping on" runs that have a dramatic effect on the stream flow.  As those are intentionally excluded from the system the result is that all reductions in stream flow, regardless of cause are assigned to groundwater pumping.

While groundwater pumping within the alluvial basin does cause a reduction in stream flow so do several other factors as can be seen from the Koelliker study.  Our estimates show that about 80% of the cause of depletions (conservation and vegetation) are excluded from the formula.  Yet, to make the formula balance with reality something has to account for the missing water.  By design, the Model assumes that groundwater pumping is totally responsible.  The DNR denies this yet, if one adds up all of the depletions the DNR estimates are caused by conservation, vegetation, groundwater pumping, and surface water diversions and adds those to existing streams flows, it doesn't work.  A simple algebraic proof shows that a reassignment of responsibility is built into the system.

Consequences of an Intentionally Flawed Computer Simulation

Because the system has been designed to exaggerate the effects of groundwater pumping it will also exaggerate the benefits of turning off groundwater pumping.  By design, the Model will report that if there is a reduction in pumping of x% that there be y acre feet added to the stream but that will not match reality.  As a result, when the actual gage reading is taken and finds there to be less water than predicted by the Model there will be calls for additional reductions in pumping. Until the forecasting tool is caused to reflect the actual causes of depletions accurately, the system will fail to achieve the purported purpose of seeing an increase in stream flows.