Gejala La Nina di Indonesia

Asia

Increased risk of floods

The La Niña event that emerged in mid-June 2010 has now developed into a moderate/strong event, expected to last through February 2011.  Frequently, La Niña events are associated with unusually wet conditions and heightened flood risk in parts of South and Southeast Asia. During the La Niña event of 2007, 69 floods occurred throughout South and Southeast Asia, more than double the annual average number of floods from 1980-2009. In Bangladesh, 4 out of the 6 most catastrophic flood years since 1954 have occurred during La Niña events. 

The seasonal forecast issued this September shows highly enhanced chances of getting above-normal rainfall in parts of south and southeast Asia (see forecast map 1 on page 6), particularly in Bangladesh (from October-December), Indonesia (from October-February), and in Malaysia, Brunei Darussalam and the Philippines from October-March. IRI’s seasonal forecast for rainfall extremes also shows enhanced chances that Indonesia, East Malaysia, Bangladesh and the Philippines will experience an extremely wet season over the months of October-December (see forecast map 2 on page 6).  The risks of flooding events are therefore notably increased. La Niña can also cause the paths of typhoons in the western Pacific to shift more towards land, which increases the chances of typhoons causing severe flooding and wind damage, and increases the risks of landslides.

Given the forecast for increased chances of above-normal rainfall, we strongly recommend making contact with national met service and monitoring weather forecasts on shorter timescales over the course of the season to anticipate the specifics in terms of where, when and how severe rainfall events might be.  You may also want to consider advanced planning for implications of above-normal rainfall on disaster management, health, WATSAN and livelihoods for instance (see background information below for further guidance).