Underground Rivers - University of New Mexico

Chapter 12 -- Superterranean Metrics
Pierre Perrault (1608-1680), Receiver General of Finances in
Paris, studied the River Seine near Burgundy, measuring the
average annual rainfall over a small portion of the upper basin for
comparison to the annual discharge from that catchment.
The portrait to the right is of Perrault, but as we'll shortly note, we
can't be certain that we have the correct sibling.
Perrault's De l’Origine des Fontaines (1674) reported that rainfall was six times the amount that
flowed out of the watershed, thus proving that precipitation was more than enough to supply the
water in the Seine and,
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Frontispiece, "De L'origine des Fontaines"
To cause this River to flow for one year, from its source to the place designated, and which
must serve also to supply all of the losses, such as the feeding of trees, plants, grasses,
evaporation…
If then this water suffices for one river, it will suffice for all the other rivers of the world in
proportion.
Perrault demonstrated by measurement that capillary rise of water was less than 1 meter in sand
and could not create a body of free water above the water table. The revolutionary aspect of
Perrault’s finding of a 6:1 rainfall/runoff ratio was that the value substantially exceeds unity.
Palissy had suggested that rainfall was sufficient to supply the total streamflow, but it took 94
years for Perrault to attach a number.
Pierre's brother Claude (1613-1688) was a physician, but became the architect of the Louvre and
translated of the ten books of Vitruvius (Chapter 3).
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