Hydraulics

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Hydraulics Mass of the Amazon Flood
Floods, which restore and damage ecosystems as
well as threaten communities near rivers, consist
of interacting flow paths of varying depth,
velocity, source, sediment concentration, and
chemistry. However, data taken from monitoring
stations along flooding rivers are geographically
sparse and are oversimplifications of floodplain
water flux. To reflect the true complexity of
floods, interferometric SAR (left side), is used
to measure water fluctuations (dh/dt) during
several floods of the Amazon River. Contrary to
many models which assume that the water surface
is horizontal and equal to the changing level of
water in main river channels, this data shows
that water surfaces during a flood have sharp
variations. Further, flow paths, previously
thought to be controlled by surface topography,
are also be driven by the hydraulic momentum of
the rushing floodwaters. The amount of water in
the annual Amazon flood is poorly known.
Geodynamics may help us to weigh this mass.
GPS data from Manaus shows the Earths
lithosphere elastically contracting and
expanding, timed perfectly with the arrival and
departure of the flood wave (respectively, right
side). Because the Amazon flood wave moves 3000
km over four months, the Amazon craton is also
likely to experience an elastic wave yet unlike
seismic waves which move at sonic velocities,
this elastic wave takes months to move.