I would contend that in the context of reporting specifically on a water shortage, a unit like km^2*cm is actually superior to m^3. First of all, that conversi

I would contend that in the context of reporting specifically on a water shortage, a unit like km^2*cm is actually superior to m^3. First of all, that conversion is actually nontrivial to do in your head. Yes, it's easy enough if you're focused on it it (factor of 10,000). Someone who doesn't frequently convert volumes could easily have an off-by-1000 error while casually reading an article. This is a kind of error that science teachers see all the time. Second, the direct "depth of flooding" value is useful both on the production side (rainfall) and for two of the largest consumers (agriculture and lawn care). The conversion therefore needs to happen twice, which is one of the usual thresholds for delaying the conversion into M-K-S.