It works out to 0.11 Sverdrups, which is a bit over half the discharge of the Amazon, but greater than any other river, about seven times the discharge of the Mississippi or St. Lawrence.
The atmospheric flux must have been much higher.
SC area 83e3 km2 = 8.3 e10 m^2depth of flood = 0.25 m
total water = 2e10 m3
time = 2 days
1e10 m3 /day at 86400 sec / day
= 115000 m3 / s = 0.115 Sv