in 2011, the meteorology, climatology and geophysics agency (bmkg) detected 23 tropical cyclones off the coast, which produced high speed winds, heavy rains, and storm surges that caused flooding and structural damage to buildings and coastal infrastructure. mangroves are adjacent to major landmasses and big rivers in indonesia, and mostly found on the coasts of large islands of sumatra, kalimantan, sulawesi and papua. the island of java, where approximately 130 million people live, is particularly vulnerable to tropical storms.