Indiana, Illinois climate trending toward fewer droughts

May 12, 2010

WEST LAFAYETTE, Ind. — Indiana and Illinois may experience severe droughts in the future, but they'll be few and far between, according to a Purdue University study.

Keith Cherkauer, an assistant professor of agricultural and biological engineering, and Vimal Mishra, Cherkauer's graduate student, used historical data from the National Climate Data Center to model the likelihood of future droughts in the two states. Historic data observed showed that those trends are expected to produce conditions in which droughts would be short, harsh and costly, but rare.

"Historically, a drought like the Dust Bowl would happen every 100 years, but what we've found is that modern droughts are shorter and can be more severe," said Cherkauer, whose results were published in the early online version of the journal Agricultural and Forest Meteorology. "The frequency of these droughts and the aerial extent has decreased significantly, however, since the middle of the last century."

Studying precipitation data from 1916 through 2007, Cherkauer and Mishra found that only one severe drought -- in 1988 -- occurred since the Dust Bowl era of the 1930s. During that time, Indiana and much of northeastern Illinois have trended toward more precipitation during the crop-growing season from May to October, a positive for corn and soybean growers.
"There is less chance of having widespread, extreme drought," Mishra said. "We may have drought, but the tendency is that we're getting more precipitation during the crop-growing season."

Cherkauer and Mishra predicted future drought conditions by studying historical precipitation trends and inputting soil moisture and stream flow data into the Variable Infiltration Capacity Model, which simulates how precipitation moves through land surface environments. 

Cherkauer warned that despite the rarity of drought conditions, droughts would be likely to occur during the later part of the crop-growing season, when the plants need moisture to produce grains.

"Yields are also much higher than they were during the Dust Bowl, so the impact of the damage would be worse," Cherkauer said.

Mishra said future research will try to determine the cause or causes of the increase in precipitation. He said global warming is likely a factor because rising sea temperatures near the equator are causing more El Niño conditions, which increase rainfall in the Midwest.

"We have seen an increase in sea surface temperatures as global air temperatures increase," Mishra said.

NASA funded the research.
Writer: Brian Wallheimer, 765-496-2050,

Sources: Keith Cherkauer, 765-496-7982,
                  Vimal Mishra, 765-494-1166,

Ag Communications: (765) 494-8415;
Steve Leer,
Agriculture News Page


Retrospective Droughts in the Crop Growing Season: Implications to Corn and Soybean Yield in the Midwestern United States 

Vimal Mishra, Keith A. Cherkauer

The Midwestern United States has experienced many severe droughts in the period of 1916–2007. We reconstructed and examined the occurrence of meteorological, hydrological, and agricultural droughts using a long-term (i.e. 1916–2007) dataset of gridded observed precipitation and simulated soil moisture and runoff from the Variable Infiltration Capacity (VIC) model for Illinois and Indiana. Reconstructed droughts were analyzed for periods of the year relevant for the development of corn and soybean crops including: (i) the beginning of the crop growing period, (ii) the grain filling and reproductive growth period, and (iii) the entire crop crowing season. Our results indicated that the most severe and widespread (affecting more than 90% of the two states) droughts occurred in the 1930s affecting the entire crop growing season for 1930, 1931, 1934 and 1936. The severity and extent of droughts have decreased in the second part of the last century with only one year, 1988, approaching the severity and extent of the droughts of the 1930s. Analysis of long-term trends in drought indices indicated that the two-state area has become wetter in the crop-growing season over the last 92 years, mainly due to observed increases in precipitation. Crop yields during the period of 1980–2007 were strongly correlated with the occurrence of meteorological drought and maximum daily temperature during the grain filling and reproductive growth period. Therefore, decreasing trends of maximum daily temperature with increased wetness create favorable conditions for better crop yields in the study domain.