Precipitation is one of the major components of the global hydrological cycle that maintains the terrestrial, atmospheric and oceanic water balance. Variations in precipitation may have serious effects on global water cycle, climate changes and societal activities.
In Thailand, rainfall variations have a major impact on the local agriculture and fresh water supply for human consumption. Excess rainfall causes severe flooding, property and lives loss. For example, in October 2003, the waters inundated the Southern Thai city of Phetchubari, causing the worst flooding the region has seen in the last thirty years. Three people died and 2460 homes were damaged (The Earth Observatory & Natural Hazards http://earthobservatory.nasa.gov/NaturalHazards/natural_hazards_v2.php3),