REMOTE-SENSING OF FLOODING IN THE US UPPER MIDWEST DURING THE SUMMER OF 1993

The U.S. upper Midwest was subjected to severe flooding during the sum mer of 1993. Heavy rainfall in the Mississippi River basin from April through July caused flooding of many Midwest rivers, including the Mis sissippi, Illinois, Missouri, and Kansas Rivers. The flood crest of 15 .1 m at St. Louis, Missouri, on 1 August 1993 was the highest ever mea sured, surpassing the previous record of 13.2 m set on 28 April 1973. Damage estimates include at least 47 flood-related deaths and a total damage cost of $12 billion. Remotely sensed imagery of severe flooding in the U.S. Midwest was obtained under cloud-free skies on 29 July 19 93 by the MODIS (Moderate Resolution Imaging Spectroradiometer) Airbor ne Simulator (MAS). The MAS is a newly developed scanning spectrometer with 50 spectral bands in the wavelength range 0.55-14.3 mu m. By com bining spectral bands centered at 2.14, 0.94, and 0.66 mu m in red, gr een, and blue display channels, respectively, false color images were created from the MAS data obtained on 29 July 1993 that dramatically i llustrate the extent of flooding near St. Louis and near Kansas City, Missouri. Estimation of the total flooded area in the MAS scene acquir ed near St. Louis was accomplished by comparing the MAS scene to a Lan dsat-5 thematic mapper (TM) scene of the same area acquired on 14 Apri l 1984 in nonflood conditions. For comparison, the MAS band centered a t 0.94 mu m and the TM band centered at 1.65 mu m were selected becaus e of the high contrast seen in these bands between land and water-cove red surfaces. An estimate of the area covered by water in the MAS and TM scenes was obtained by developing land/water brightness thresholds from histograms of the MAS and TM digital image data. After applying t he thresholds, the difference between the area covered by water in the MAS and TM scenes, and hence the flooded area in the MAS scene, was f ound to be about 396 km(2), or about 153 square miles.