WMOD00259

• Applicant: Western Kansas Groundwater Management
• Project Name: Western Kansas Weather Modification Program
• Date: 1/1/1999
• Weather Modification - Doc Type: Report

I
I
I
I
I
I
I

One problem with rainfall is that it doesn't always fall in the amount needed or at the time
needed. Therefore, the whole story of how useful rainfall is whenever it falls is never accurately
known. This was one of the main points the Kansas Water Office made in its evaluation of the
WKWMP several years ago. Due to the rainfall variability, slight increases, or decreases, in.
rainfall probably doesn't mean much to the whole crop-growing picture in any given year. For
instance, how many fanners want or need a one-inch to two-inch rainfall at the time they are
trying to harvest wheat? Would less rainfall or no rainfall be preferable at that time? Or how
about just after planting, would a one- to two-inch hard, eroding rainfall be preferable to less
rainfall and/or not as hard-driven which would cause re-planting?

Rainfall will always be variable and each fanner's water need itself will vary among the
total farming community due to the type of crop( s) being raised and the condition of the crop at
the time. Trying to make economic sense out of an average percentage increase or decrease of
rainfall borders on being a futile exercise. Interesting, yes, but having being true meaning is
doubtful---without assumption after assumption thrown in. When clouds are seeded expressly to
increase rainfall, assuming increases do arise from the seeding, one may get several hundred or
thousands percent increases above what the original cloud would have produced, or he may
receive relatively little. Percentage rainfall increases vary greatly among seeded clouds and single
storms only affect a relatively small area, not an entire target area. It's likely some areas inside a
target area are affected rarely during a season while other areas may be affected often.

I
-1
I
I
I
I
I
I
I

Rain falling at a certain time of year will have a definite impact on any crop either helping
or harming its eventual yield. But, if one doesn't know what stage of development each crop is
during the season, or how much rain will fall from a given storm, etc., how can the economics of
relating increased rainfall to crop production be calculated with any credibility? How valid will be
any calculations except without many assumptions of dubious value thrown in? The reason a
percentage increase (or decrease) of rainfall number is needed is because the public and weather
modification sponsors inevitably get caught up in the funding aspect of the program and demand
to know what are the average percentage increases (or decreases) so some calculation can be
made to justify continuing the weather modification program. What is found isn't real; it doesn't
mean too much except to indicate that it appears rainfall is increasing or decreasing in smaller or
greater amounts. Naturally, the larger the apparent percentage increases, the more it tends to
make one believe there is a high success rate, or vice versa. Trying to make economic reality out
of rainfall changes creates a challenging problem having an infinite number of answers.

At the WKWMP our long-term objective is to o.ptimize rainfall and let the percentage
changes take care of themselves. Our technology is firmly based in science and it is enough to
know we're intentionally attempting to produce the best precipitation result. Often, we mis-state
our objective when, inadvertently, we say our objective is to maximize rainfall. If flooding were
occurring, obviously we wouldn't want to increase rainfall. In fact, what we really are attempting
to do here is to maximize 'beneficial' precipitation.

48