probably the most threatened population on the island live in the city of Gonaives.. In the post that Bob put up, the sea surge in that bay are predicted for 3 to 5 feet.
http://earthobservatory.nasa.gov/IOTD/view.php?id=35398
est 300,000 people live in Gonaives (2011 )
here is a satellite map
http://mapcarta.com/19795072
Gonaives is trapped between the mountains and the sea.The first link provides a very good analysis of the storms and pictures of them.
the floods in 2008 were very bad.. causing many people to be stranded on their roof tops for many days
a lot of money was collected for relief efforts.. some of which was spent giving the survivors the extremely valuable gifts of uncooked rice and beans. What more could one want while stranded on a roof than uncooked rice and beans?
oh.. and water.. they did give water
All of the storm drains had been built over by then - back in 2008
one assumes that none of the money was spent in clearing the storm drains.
that is not just on Haiti, .. that is on the amazing capacity of the international aid organizations to spend the aid money in their respective countries of origin before they get to Haiti..
(Sorry for the off track and the snark but it positively amazing to watch the dysfunction of foreign aid as I have watched for the last 12 years in Haiti. Certainly not everyone was on a roof and the rice and beans were needed-- and everyone had the best intentions.. except for the ones who did not)
But - as I see it.. these are the people in the most danger in Haiti.,
I do not know Jamaica and so can not speak to that.