Underground Rivers - University of New Mexico

Chapter 12 -- Superterranean Metrics
An historical fact, Claude Perrault was the architect of
Versailles and Mariotte, the well-driller. The history of
scientific hydrology is indeed one of crossed paths.
Water Tank, Versailles
Current estimates of the precipitation/runoff ratio are summarized below by continents.
Precipitation
(mm)
Evapotranspiration
(mm)
DRAFT 1122//66//22001122
Runoff
(mm)
Precipitation/
Runoff
Africa 690 550 140 4.9:1
Asia 720 430 290 2.5:1
Australia 740 510 230 3.2:1
Europe 730 410 320 2.3:1
North America 670 380 290 2.3:1
South America 1650 1060 590 2.8:1
Perrault's and Mariotte's fundamental breakthrough wasn't the precise precipitation/runoff ratio; it
was that its value significantly exceeds 1.0. The perception that rivers bear more water than the
upstream rainfall was at last disproven.
As well-builder for the Palace of Versailles, Mariotte put his findings to practice. In the world’s
first application of hydrologic modeling, Mariotte calculated that 100 square kilometers should
supply the palace's water need. The channels, however, couldn't transmit the flow and so fared
the first application of hydrologic design.
Three Englishmen
English astronomer Edmond
Halley (1656-1742), son of an
industrial soap-maker, is best
remembered for the comet
honoring his name, but his
most influential contribution to
science was that of translating
the works of his friend Isaac
Newton from Latin to English.
Noting the likeness of comets observed in 1531, 1607 and 1682, Halley concluded that all three
were in fact the same object and correctly predicted its 1758 return. Halley's contribution to the
science of hydrology stemmed from the condensation on his optical equipment on clear day, 730
meters above the Mediterranean, making the astronomer to be among the first to appreciate the
magnitude of atmospheric water.
Halley filled a 20-centimeter pan half-full with salt water and heated it to the temperature of a
summer day. In two hours, 0.5 ounces were evaporated. Estimating the surface of the
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