Expect extreme weather changes

Sri Lanka can expect an increase in the frequency of extreme rainfall events, warns Sarath Premalal, Director General of the Department of Meteorology. Speaking to the

Sunday Times, Mr Premalal said that the increase in global temperatures can lead to an increase in frequency of the ‘extreme rainfall’ events, and will likely cause flooding, prolonged dry periods and droughts in the coming years. Rainfall is now occurring in two extremes; heavy rainfall within a few days followed by long dry periods, he explained. As such, in the future, the dry zones will get drier as the temperate continues to rise, he noted. According to a United Nations report, Sri Lanka has been experiencing a lack of rainfall since late 2016. It is believed to be the worst drought in 40 years.

The Meteorology Department prepares projections on future weather patterns taking into account global greenhouse gas emission based on projected development trends, net global thermal radiation and historic local weather patterns. Mr Permalal expressed his concerns regarding ongoing deforestation noting that forests play a crucial role in soil water retention. According to the Met Department, Sri Lanka on average receives 1,861mm of rain per year. However, close to 59% of it evaporates back into the atmosphere before being absorbed into the soil. When an extreme rainfall event occurs, if good soil water retention does not occur most of the rain water moves laterally on the surface causing floods he explained. Therefore, floods may become an even greater threat as the world warms. In urban areas the situation is further exacerbated. Many urban centers have poorly planned or managed rain water drainage systems and absorption into the ground is limited due to soil compacting, tarring and the use of concrete or interlocking brickwork.