Better flood defences are always a good idea but not so easy to put into practice. It’s a bit like asking British Rail to protect against leaves on the line or the wrong type of snow.
The Gota Fria, like Easter is a moveable feast, sometimes it comes as early as mid August and other years in late September.
Not only that but it is a geographical moveable feast, no one knows which area is going to get hit hardest or when.
As you mention, one of the few things that can be easily done is maintaining the torrents and my feeling is that this is much higher in the list of priorities than it was years ago.
However one thing that is very hard to protect against is “ the hundred year event”. Recently Sant Llorenc was one, and in 1989 the whole of the east coast was another. That year three employees died in the basement of the Hotel Corsa in Portocolom and the reason they died was because the hotel is built across the outflow of a torrent into the harbour. That torrent only flows on these very rare occasions and sadly when the hotel was built no one took that possibility into account.
Without wishing to scare people there is another area where a serious problem exists and is waiting to happen. The whole of the area behind the main beach at Santa Ponsa is a flood plain. In that area you will find a school, a church, a health center, a sports field with football and tennis courts, commercial premises, several hotels and housing. All built since 1963 and I have a photo proving that fact.
The catchment area for this torrent (Barranc de Cohans) is enormous, stretching up behind Calvia into the Serra de Tramuntana.
Usually the outflow of the torrent can cope, it is modern concrete lined and clean. However should an event as described above ever occur then people who find themselves near the outfall should be prepared to move fast.
The best way to prepare is to be aware.