PORT-AU-PRINCE, Haiti -- A hard rain can be deadly here. A family of four was reported killed late last month when rushing stormwater loosened soil under their hillside house and brought the structure down on them. The denuded slopes around this city of 2 million turn stormwater into lethal torrents. Trees, shrubs and other vegetation that anchor soil and buffer runoff are rare here. They mark private compounds of the wealthy, islands of green protected by fences and armed guards in a sea of slums that have sprawled up sandy hills as the city's population tripled over the past 20 years.