The reason Haiti is so devoid of vegetation is that the winds which bring rain, etc., to DR are blocked by the hills in the middle of the island... right along the border.
Port-au-Prince receives around 55 inches of precipitation annually. Plenty enough to make it green!
Is Haiti small enough that one large modern nuclear plant built there and run by foreigners (to start) could power the country PLUS a large desalination plant for plenty of fresh water for people, industry, and crops? Seems more forward sighted than just giving them food which only creates a need for more food...