Hi !
I have also enjoyed advanced civilization for lots of years and after reading trad2bay's post I have to totally agree with him according to the explained in point two of his post.
Currently we are playing a civproject cyberboard game ( 9 people , all of them experienced players ) and this turn we had to face up a similar situation.
I explain myself: one of the players had CIVIL WAR calamity, and during the trading round he has been trading to obtain the maximum number of calamities to try to avoid the CIVIL WAR effect. Once the trading round has finished he had in his own 5 different mayor calamities in adition to the civil war. Like rules said I have stacked and suffled all of them and randomly I have chosen two calamities and discarded the remaining ones. The chosen ones have been superstition and civil disorder. This guy was ruling a really big empire, having a lot of trade cards and avoiding in this way the civil war effects.
This is only an example of something I have seen in a lot of diferent games.
Currently we are in turn 13 and from here to the end of the game will remain 5 or 6 more turns so no more much civil wars will appear.
I know this is a valid strategy and doesn't go against the rules but in my opinion disrupts the balance of the game. Some other civilizations were eagerly waiting for a civil war to have the posibility to raise their empires. And now they can see how most of this turn calamities ( most of them belonging to the greatest empires) are discarded with no effect and the civil war vanishing in their face.
To reduce the effect of civil war we have several civilization cards and using this strategy We are also reducing the importance of this cards.
I have a proposal to avoid this kind of situations, maybe the rules could be changed in the following way:
"24.3 No player may be the primary victim of more than two major and one minor calamities in the same turn. If a player receives more than two major calamities in the same turn he will first discard any duplicates. If he still has more than two, his TRADABLE major calamities are shuffled together, and one is drawn at random. If he still has more than two the same will done with the NON-TRADABLE ones. The remaining major calamities received by that player are
disregarded and are returned to the appropriate stack of trade cards. The same process is then followed with minor calamities with only one minor calamity being selected. There is no restriction on the infliction of secondary effects of calamities."
Doing this the effect described in the example will be avoid.
For our next game I'm thinking in use parragraph 24.3 in this new way.
It would be glad listening to your opinions about this issue.
In the other hand for an upcoming variant of civproject game I have added also a Drought calamity working in a very similar way than yours. It's a 5 non-tradable (in substitution of FLOOD ), the main difference it's that agriculture works. We have had the same idea several thousands of kilometers away!!

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For more info about this variant see my web page :
http://www.civiboard.com/hellas/Best regards.
Jon G.