WRT DTA flooding, that is a sadly normal occurrence with heavy rain over extended periods, high tides, full moons and storm (hurricane, nor'easter) surge. Pick any two of the above, and the water comes up over the low breakwater at Ego Alley (where Alex Haley's statue is). It usually just goes into the businesses along Dock St., which is why they have brick, concrete or stone floors, with a sandbag pile ready to deploy. There is simply nowhere for the water to go when storm drains into the Chesapeake are blocked by high water in the harbor.
The Yard has low-lying areas that get flooded, usually over by the Columbarium, near the footbridge behind the library, and along the quay walls facing the harbor.
Usually scheduled outdoor training goes unless there is lightning, extreme heat or extreme cold. I always think Marines are secretly happy when it's nasty weather for training, rather like the Green Bay Packers playing at home while it's snowing heavily.
See below photo of Alex Haley statue during the worst flooding of recent memory during Hurricane Isabel in 2003.