Fourth Wettest April-May Since 1895, Illinois State Water Survey

Press Release

For Immediate Release May 14, 2002
Fourth Wettest April-May Since 1895

Source:   



Contact:   
Bob Scott - (217) 333-4966, Fax: (217) 244-0777, rwscott1@illinois.edu
Sally McConkey - (217) 333-5482, sally@illinois.edu
Bill Saylor - (217) 333-0447, wsaylor@sws.uiuc.edu
Stan Changnon - (217) 244-0494, schangno@illinois.edu
Eva Kingston - (217) 244-7270, Fax: (217) 333-6540, eva@sws.uiuc.edu
Heavy rainfall over Illinois last weekend has continued to cause flooding across the state and is likely to lead to considerable delays in farming operations over much of Illinois.

Numerous rivers and streams are above flood stage in many communities. Nearly saturated soils that resulted from extensive rainfall totals over the last several weeks were not able to hold much, if any, of the 3- to 4-inch rainfall totals that fell over the central half of the state on May 11-12, leaving widespread ponding in farmfields across the region.

According to Bob Scott, Program Manager of the Water and Atmospheric Monitoring Program at the Illinois State Water Survey (http://www.sws.uiuc.edu/), "these new rainfall totals added to the 8- to 9-inch amounts across southern and central Illinois between April 7 and May 9, and are yielding near record rainfall totals in south-central Illinois."

Hardest hit areas are located in an area bounded roughly by Springfield on the north and Salem on the south. Here, rainfall amounts since the first week of April have averaged between 12 and 14 inches--about 275 percent of normal--with individual locations, such as Beecher City in Effingham County, receiving up to 18.75 inches of rain.

"With just over two weeks left in May, rainfall totals in this part of the state already qualify as the fourth wettest April-May period on record since 1895. Only normal rainfall totals of about 2 inches before the end of May are required to exceed the current precipitation record for the April-May period," says Scott.

"While out-of-bank flooding is occurring in many locations, provisional river flow and stage data in southern and east-central Illinois are notable, as they are very high compared to long-term records," says Water Survey hydrologist Sally McConkey.

According to current provisional river stage and flood stage for gaged rivers in Illinois reported by the U.S. Geological Survey, "the average flow recorded for the Kaskaskia River at Vandalia through May 13 exceeded the maximum average for any month since records began in 1970, and the daily mean flow of 20,600 cubic feet per second (cfs) on May 8 approached the maximum daily mean flow of 23,900 cfs. In addition, the peak flow of 27,600 cfs on May 5 was close to the record peak of 30,000 cfs set in 1970," says McConkey.

Heavy rainfall also has filled lakes and reservoirs. Flow recorded at Vandalia is affected by controlled releases from Lake Shelbyville, which on May 13 "was more than 12 feet above target level and rising, although about 8 feet below the maximum level record in 1974," said McConkey.

Carlyle Lake, another flood control reservoir downstream of Lake Shelbyville is nearly 10 feet higher than the target operating level and is approaching its record high. Rend Lake currently reports a water level 6 feet higher than the spillway.

Shoal Creek near Breese in the Kaskaskia watershed recorded a peak flow on May 10 that approached the 23,100 cfs record peak set in 1950, and flows during the first two weeks in May averaged about 7,800 cfs, far above the maximum monthly average.

In the Little Wabash watershed, the Skillet Fork at Wayne City had an average flow much above normal for May (as of May 13), and the Little Wabash River at Clay City had an average flow that exceeded the maximum monthly average for any month. Both rivers are still rising. Average monthly flows on the Embarras River at Ste. Marie also exceeded the maximum May average flow. Flows recorded for the Big Muddy for the first two weeks in May at Plumfield were above normal for May, and both the Sangamon at Monticello and the Mackinaw River at Congerville have experienced flows much above normal for May.

The duration of high flows on these tributaries also has contributed to significant high water levels on major rivers. Water Survey staffer Bill Saylor reported that, "as of May 13, the Illinois River has reached stages 6 and 7 feet above flood stage, the Mississippi River from Quincy to Thebes is well above flood stage, and the Ohio River is 10 feet above flood stage at Cairo."

Widespread ponding in farmfields, the other major impact of the heavy rains, is occurring during the middle of the planting season. After many rain delays, farmers were putting in long hours in northern portions of the state but remained out of the fields in southern areas.

The most recent Illinois Weather and Crop Report states that as of May 12, "corn planting statewide progressed to 51 percent with 86 percent in the northwest to six percent in the southeast." This statewide planting total compares with 96 percent last year and a five-year average of 78 percent.

The report confirms that the recent heavy rains greatly affected working conditions as the "days suitable for fieldwork averaged 2.2 days across the state, with the high being 5.4 days in the northwest and as little as two-tenths of one day in the central part of the state."

Thus, "many planted acres of corn are suffering from poor emergence and numerous drowned out spots. Soybean planting is progressing although well behind last year and the five-year average. As of Sunday, only ten percent statewide had been planted... compare[d] to 66 percent last year and a five-year average of 37 percent."

The timing of the heavy precipitation was very unfortunate for farmers, says Water Survey Chief Emeritus Stan Changnon. "Not only is everything saturated, but I suspect there has been severe erosion and soil loss. A lot of this heavy rain occurred after farmers had worked the soil in preparation for planting," said Changnon.

Extreme wetness during the planting season is relatively rare in recent years. The springs of 1995 and 1996 produced heavy rainfall totals, similar to those this year. "However, rainfall in both years followed quite dry periods as February and March were 35 to 45 percent below normal, respectively, whereas precipitation during that period this year was near normal," said Scott. Thus, existing soil conditions and timing of the precipitation in those years were such that most of the planting was in before heavy rains began.

The spring of 1982 also was noteworthy, with lots of flooding in central and southern Illinois, due in part to a rather wet winter season. "That year the rains ended in mid-April in time for drying, and only a slight delay in planting occurred," said Changnon.

Data sources:

U.S. Geological Survey: http://il.water.usgs.gov/nwis-w/IL/datasum.components/owrtable.cgi?table=norm

Midwestern Regional Climate Center: http://mrcc.isws.illinois.edu/

Illinois State Climatologist: http://www.sws.uiuc.edu/atmos/statecli/index.htm

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