Hi,
you shouldn't need to do any flood estimations,
your local government, dam/city/county/state/country,
should have published inundation maps specific to dams,
there should also be some evacuation plans,
...
years back I checked and if I recall correctly
hazards.fema.gov
didn't have dam data
...
I watched the tv news report on the hole opening ,
two people hiking and called it in,
stayed to watch, and then for the interview,
...
I thought it was a good time to pack and review/check plans,
...
then later the hole is reported as 200 foot
...
I thought a good time to inquire about hotel reservations
and check road conditions with google and other sites
...
naturally the tv news just marveled at the spectacle,
until the evacuation was called no real thoughts of preparation were hinted at, only the potential for disaster , fear sells
...
after catching that on the news, I either read or heard about a resident new to the area returning a reverse 911 call to ask for driving directions to a hotel,
...
I thought whoa, I would never think of that ...
then a minute later I remembered I'm exausted and sleepy
but despite that , stop/think/observe/plan, it works
...
regarding road conditions, I checked for highway flooding for the first time last week, spent a good half hour trying to decide if the hazard report meant the highway was blocked or just the exit that was flooded,
and no I wasn't sleepy then