ALL the land area of New Orleans is NOT flooded, so your "200 square mile" number is bogus. Of the land area that IS flooded, we have no idea of the average depth, so your "model" is pretty much useless.
So, where are the 1000 pumps then?
I've thinking about this problem all week.
I think the flooded area is less than 60 sq miles (from guesses based on simulations and satellite photos)
And, the depth varies from 0 to 8 feet at the maximum flood. The water is now down to 0 to 6 feet feet from the pictures I've seen. LP is slowly draining lowering the level.
Therefore I figure 180 sq mile feet of water or 180*640 acre feet.
Pumping station #6, the largest one, can pump 850 cu ft per sec. or about one acre foot per minute. 60 acre feet per hour. If pumping station # 6 alone is all we have it would take about 2000 hours, or 80 days.
3 times pumping station #6 would do it in 27 days.
This range is pretty well in agreement with Corps estimates of 36 to 96 days after full pumping starts.