The flood happened over the weekend, a slow news time typically, but the riots happened at the same time and essentially drowned it out, along with the olympics and some untimely comments by a certain rascal wannabe politician.
Further, the flooding "only" affected 40,000 homes, and resulted in deaths in the low double digits.
Compared to Katrina, which affected 500,000+ homes and resulted in triple digit deaths, this wasn't as big. Not only that, but the changes the administration made in FEMA and other response agencies means that they are much better able to deal with situations like this than they were in Katrina's time.
Lastly, sad as it is, and destructive as it is, if you look at the list of floods since Katrina this is notable, but not unusual for states containing the mississippi and its larger tributaries. This specific area rarely receives floods (and thus flood insurance is unnecessary, which is only going to be all the more devastating for those affected) but the area of the flood, and the number of people affected isn't much more than those that do live in flood plains, and the media has simply stopped reporting on flooding unless it's multi-state or affects millions.
Despite that, the public seems to be aware of it, and many, many people are providing support in various ways.
All this means that Obama's golfing trip wasn't interrupted, which I'm sure he appreciates.