afflux

noun2

1. •
   An upward rush of fluid.

   • The vis viva of these affluxes is employed almost wholly in turning the mass of intermediate gas […] — 1874
2. •
   The rise in water level (above normal) on the upstream side of a bridge or obstruction caused when the effective flow area at the obstruction is less than the natural width of the stream immediately upstream of the obstruction.

   • Backwater due to the crossing as a whole should not be confused with local afflux at piers due to pileup of flow against the hydraulic stagnation point […] — 2004