This kind of information was a factor in the prediction of major flooding in the northern Midwest for later in the Spring of 1997. This bore out with the great floods on the Red River in North Dakota and Manitoba (Canada) that inundated Grand Forks, Fargo, and other towns. The flood on April 27 was imaged by a NOAA AVHRR, with light gray representing the water (clouds in orange):

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, as captured in this Landsat-1 subimage (with an earlier pre-flood view) on a cloudfree day, showing St. Louis, Missouri (protected from downtown flooding) and the floodplains of the Mississippi, Missouri (joined at A), and Illinois (B) river:

Twenty years later, the Midwest was again subjected to a flood of even greater magnitude. After several months of excessive rain that saturated the soil, owing to a blocking high that kept the jet stream in a relatively fixed position, in late July and August of 1993 water levels had risen 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 costliestin U.S. history (some estimates approach $15 billion). This time a number of good images were obtained by radar. Once again we examine the lowlands northwest of St. Louis. One image taken by the Shuttle astronauts using SIR-C appears on the top. On the bottom is an image consisting of merged JERS-1 radar and a SPOT 3-band composite which offers considerable detail (notice how farmlands show through the water).

The last image we present is a Landsat-1 subscene (February 6, 1974) of the Barcoo River in Queensland/South Australia in flood from Fall rains. The floodwaters have spread out to widths greater than 50 km (30 miles) in this plains with low rolling hills.

This lengthy Section 14 purports to convey the idea that, in keeping with the widespread occurrence of water on the Earth's surface (even greater than the 70+ % area topped by oceans stated on p. 14-1 if the ice covering the Antarctic [which stores more than 80% of the world's {frozen} fresh water] and Greenland are taken into account), the principal use of remote sensing since the Space Age opened remains surveillance of the weather systems and oceans at scales from local to global. At this point in the Tutorial, we have now examined most of the specialized modes of remote sensing (defined by the electromagnetic spectral regions utilized), the spacecraft systems and programs that mount the sensors, and the numerous and varied applications to which these sensors have contributed. In the next section, on GIS, we will learn of some systematic ways in which remote sensing data are integrated 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 meteorological, oceanographic, land surface, and biologic observations will be made by a series of satellites dedicated to presenting a unified picture of the Earth as a System.

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