This kind of information was a factor in predicting the major flood in the northern Midwest, late in the Spring of 1997. Satellite imaging gave a critical look at the great floods on the Red River in North Dakota and Manitoba (Canada) that inundated Grand Forks, Fargo, and other towns. A NOAA AVHRR imaged the flood on April 27, with light gray representing the water and orange depicting clouds:

Spring flooding is frequent in parts of the Mississippi River basin. A hundred-year flood, i.e., largest expected statistically in a 100-yr span resulted from snow melt and rain in late March of 1973. This Landsat-1 subimage (with an earlier pre-flood view) captured the extent of flooding on a cloud free day, showing St. Louis, Missouri (protected from downtown flooding), and the flood plains of the Mississippi, Missouri (joined at A), and Illinois (at B) rivers:

Twenty years later, the Midwest again flooded, worse than before. After several months of excessive rain that saturated the soil, because of a blocking high pressure system that kept the jet stream relatively stationary, in late July and August of 1993, water levels rose well above flood stage. Areas hardest hit were from Iowa to southern Illinois. Levees broke, inundating tens of thousands of acres. The '93 flood became the costliest in U.S. history (some estimates approach $15 billion). Satellite imaging played a key role in getting a number of good images of the flooded area. Once again we examine the lowlands northwest of St. Louis. One image taken by Shuttle astronauts, using SIR-C, appears on the top. On the bottom is an image of merged JERS-1 radar and a SPOT 3-band composite, which offers considerable detail (notice how farmlands show through the water).

14-41: Which year does the Mississippi flood seem worse? Why isn't St. Louis flooded? ANSWER

The last image we present is a Landsat-1 subscene (February 6, 1974) of the Barcoo River in Queensland/South Australia, flooded by Fall rains. The floodwaters have spread greater than 50 km (31 mi) wide in these low-lying plains, with low rolling hills.

This lengthy Section 14 purports to convey that the principal use of remote sensing remains surveillance of weather systems and oceans on local-to-global scales. We report this because of the widespread occurrence of water on the Earth's surface (even greater than the 70+ % ocean surface area, stated on page 14-1, if we include the Antarctic ice [which stores more than 80% of the world's {frozen} fresh water] and Greenland.

At this point in the tutorial, we have examined most of the specialized modes of remote sensing (defined by the electromagnetic spectral regions we can use), the spacecraft systems that mount the sensors, and the numerous applications to which these sensors have contributed. In the next section, on Geographic Information Systems (GIS), we look at some systematic ways to integrate remote sensing data into organization, correlation, interpretation, and management of geographically-referenced information. Then, in Section 16, we look ahead to the next generation of remote sensing programs, in which satellites will make meteorological, oceanographic, land surface, and biologic observations to present a unified picture of Earth as a System.

Collaborators: Code 935 NASA GSFC, GST, USAF Academy
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