This SIR-C/X-SAR radar image of the Rio Sao Francisco in eastern Brazil shows an area 16.5 kilometers wide, centered at 9 degrees south latitude and 40.2 degrees west longitude. The region was originally settled by speakers of Tupi, Ge, and Arawak languages. After 1600 a number of Dutch trading colonies were established along the nearby Caribbean coast.
The NASA/JPL image, a composite view taken from the space shuttle Endeavour on April 10 and October 1, 1994, has been used to help estimate the size and productivity of planting areas. Such projections are made difficult in Brazil by prevailing cloud cover during the rainy season (November through April). The SIR-C radar apparatus effectively overcomes these difficulties, by literally seeing through the clouds. The floodplains of the Rio Sao Francisco lie within a semi-arid region of Brazil. Some planning estimates have shown that up to 10 times more land could be used for local agriculture, given more efficient use of irrigation methods.
In this composite image, red represents the data acquired on April 10, 1994, and green represents imaging on October 1, while blue corresponds to the ratio of the two data sets. In April, at the end of the rainy season, the area was covered with vegetation , while in October the run-off channels of the hilly terrain are much more visible, due to the lower soil moisture of the dry season.
[Fig.1: Rio Sao Francisco at Bebedouro (NASA/JPL image P-44734).]
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