News release: Drought Comparisons

Tim Baker, MU Extension Professional Field Specialist in Horticulture
102 N. Main, Suite 1, Gallatin, MO 64640
660-663-3232, bakert@missouri.edu

Release Date: August 30, 2018
Headline: Drought Comparisons

When we consider this year’s drought, there is a natural tendency to compare it to past droughts.  Our most recent drought was in 2012. Is this one as bad?

There are many ways to compare droughts. I think in many ways, our drought this year is not as bad as 2012, but in some ways, it is worse. Local comparisons are difficult to make because of the location factor… some areas in some years may receive more or less than other places. Therefore, you have to look at the overall trends.

On my drought web page (http://extension.missouri.edu/nwhort/drought.aspx), I have several comparisons that you can see.

One of the first projects I decided to do was to create a video comparing the drought monitors (DM) for each year, starting in January. You can see that we started out 2012 in NW Missouri in pretty good shape.  It wasn’t until the DM of May 22, 2012, that some NW Missouri counties even became abnormally dry. However, we were already abnormally dry when we entered 2018. This is because the last half of 2017 had experienced below normal rainfall, with areas abnormally dry or even in drought from time to time. So the soil profile was already moisture deficient when we entered 2018.

Another project I have on my web page is to take photos to compare the same locations at the same time of the month in 2012 and 2018. This, of course, can be wildly variable, depending on whether an area received rainfall or not in each year. Showers are usually spotty.  However, it was still an interesting project.

While we have experienced some hot days in 2018, it is not nearly as hot as 2012. Much of the problem in 2012 came not only from the drought, but also from the very high temperatures. This increased evapotranspiration (ET) rates, and thus the water demand for plants of all kinds, including trees.

While high ET rates certainly reduced the amount of soil moisture very quickly, the soil moisture profile was actually in fairly good shape until later in 2012.  In contrast, our soil moisture started out in poor shape in 2018, since we had been abnormally dry throughout the last half of 2017.

We can also compare the situation with our city reservoirs in both years.  Several cities have been hit hard, including Cameron and Hamilton. I discussed the situation with the water plant for Cameron. They have a reservoir that they pump from when the situation in their main reservoir becomes critical. In 2012-2013, the level of that auxiliary reservoir still had 9 inches of water left at the lowest point. This year, they have already reached the lowest point they can pump from. In other words, it’s lower.

So is the drought of 2018 better than the drought of 2012?  Looking at trees, and the amount of heat, I would say we are better off this year. However considering the soil profile deficiency we started out with in 2018, it has potential to be worse than 2012.  It just depends on how soon dependable rains start again, and how much we get. And from the situation with city reservoirs, we are definitely worse off this year than in 2012.  Another comparison will be crop yields in both years. That comparison will have to wait until the numbers come in.