Wednesday, 15 May 2002: 8:00 AM
Measured Soil Moisture during the 1999–2000 Drought in Illinois
The 1999-2000 drought in Illinois began in July 1999 with large precipitation deficits in the fall. While near-normal precipitation prevailed in winter, dry conditions returned in spring. Impacts were felt in soil moisture, surface water, and groundwater supplies. Fortunately, precipitation was above average by May and June 2000, allowing for a recovery of the water cycle to begin. Near surface moisture conditions responded quickly to the precipitation increase, but a large moisture deficit below 1 meter continued across parts of northern and central Illinois into early 2001. Soil moisture measurements down to 2 meters have been taken since 1981 at 17 sites across Illinois using a neutron probe. The observations are made twice a month during the growing season (March-September) and once a month during the remainder of the year. The soil moisture measurements allowed for a three-dimensional view of the drought over time. The presentation will review the behavior of soil moisture data and compare the results with more traditional measures of drought such as precipitation departures and the Palmer drought indices.