It’s 3 pm and it looks like seven o’clock at night. Only a few hours of rain and the whole city along with the suburbs are inundated, grounding the transport system to a halt. Why? Oh it’s only the hottest year in 115 years, an El Nino year and the year with the strongest Madden Julian Oscillation(MJO) event on record. Too technical, the last little bit about the MJO went over your head? Nation Weekend spoke to a few experts in the fields of climatology, meteorology and transport to ‘clear things up’, no pun intended.
The freak weather that Colombo and the suburbs experienced over the past few days as well as the Chennai floods is probably a part of an accelerated global climate change event, opines a climatologist. “This year has been identified as an El Nino year, and the year with the strongest Madden Julian Oscillation event on record,” says Colombo University, Geography Department, Senior Lecturer, Savthri Ranasinghe.
Madden Julian Oscillation is a pattern of increased thunderstorm activity near the Equator that moves around the globe in 30 to 60 days. According to Weather Underground’s article titled ‘Strongest MJO Event on Record Boosts El Niño Odds’, MJO index reached 4.09 on March 15, 2015, beating the old record of 4.01 set on February 14, 1985. On March 16, 2015, the MJO index set an even higher mark of 4.67.
Ranasinghe explains that the increase in intensity and frequency of El Nino is indicative of climate change. This increases evaporation and cloud formation, an environment conducive to rain, explains Ranasinghe. She points out that 2015 is also the hottest year in 115 years. News from the UN’s weather agency, that it’s the hottest year on record, arrived just in time for the global climate summit in Paris. According to World Meteorological Organization (WMO) the years 2011-2015 were the warmest five-year period on record, with many climate change induced extreme weather events, such as heatwaves.
This begs the question, is Sri Lanka ready to face such extreme weather events? Colombo Municipal Council, Drainage and Water Supply Division, Director Engineering, MIM Salim says we are getting there. The existing rainwater drainage system is between 35 to 40 years old, long overdue for an upgrade. Under the Metro Colombo Urban Development Project, funded by the World Bank, 15 critical flood-prone points in Colombo have been earmarked for development. “Horton Place roundabout, Wijerama junction, Gregory’s canal and Devi Balika junction are among the points identified, informs Salim. The project involves doublings the size of the existing drainage pipes. Most of the existing drainage pipes are too narrow. These will be upgraded to pipes three meters in width. The project of revamping the drainage system is estimated to cost approximately Rs 8000 million. “So far we have received only Rs 4000 million.”
Salim explained that it is not so much the amount of rain received that has increased, but the intensity. An average 50 ml of rain an hour was recorded in 2012 whereas rainfall has more than doubled by 2015 to 101 ml an hour. These are severe short duration storms, inflicting more pressure on the drainage system.
Most water retention areas have been subject to land filling for infrastructure development. Plots of land are walled up trapping pockets of rainwater. To top it off all open ground has been carpeted. This prevents rain water percolating into the ground. Natural drainage pays no heed to administrative boundaries. Consequently most drains fall along private lands and upgrading them would entail tedious legal procedures that may take years to clear. It would also mean having to realign most of the service lines such as electricity and telephone.
“The whole drainage system is substandard,” agrees General Manager of Railways, BAP Ariyaratne. “The whole city is inundated with only a few hours of rain.”
Usually the transport system has to bear the brunt of it. Railway tracks are inundated and rampant signal failures delay trains by hours if the floods persist. “We have to follow certain protocols if the tracks are under water,” says Ariyaratne. The Department of Railways uses diesel electric and diesel hydraulic engines, explains Ariyaratne. If the water is one foot over the tracks the protocol is to stop the train because diesel hydraulics run on a complex of motors. “We are forced to either halt operations or switch to hydraulics, which is time consuming.”
Moreover repeated inundation causes the deterioration of railway tracks, causing a myriad of maintenance issues. Signal systems often malfunction during rain. But ‘malfunction’ does not necessarily connote danger. Ariyaratne explains that malfunctioning signal is indicated by red light and this is the driver’s queue to stop.
According to Ariyaratne a long term plan to upgrade the whole railway system is in the pipeline. But for such a large scale project some 1000 unauthorized structures would have to be cleared, railway line raised and new drainage system put in. Unauthorized structures are built on filled reservation ground, causing the inundation of the tracks. Earth slips like the one in Nugegoda on the Kelani Valley line are rare in the Western Province, but slope protection mechanism will be introduced to upcountry railway lines, he informs.
All in all it would come as a comfort that weather is expected go back to normal in January, when the El Nino effect is expected to subside. However if the recent freak weather is, in fact, related to climate change rest assured we can expect similar floods next year.
Effects of rains on the road networks are twofold, during rains and after rains, explains Road Development Authority (RDA), Chairman, NR Suriyarachchi. Infrastructure is designed according to rain capacity and intensity. Our infrastructure is designed according to average rain intensity.” Anything above this grade is considered too costly, explains Suriyarachchi.
Any changes to this design in the form of construction work affect the design’s capacity to deal with extreme weather conditions. “Take for example the Arcade at Bullers Road,” says Sooriyarachchi. “Before it was built there was enough exposed ground for water to percolate. But after the whole area was covered with concrete there was 100% surface runoff. Simply put, all the rainwater flowed to the drains since the concrete prevented it from being soaked into the ground. The drainage and sewage system cannot be ignored in the city beautification process,” emphasizes Sooriyarachchi. In case of rain intensity above design standards, a result of climate change, or in case of construction work to the design, the rainwater drainage system has to be widened.
When asked about the lack of coordination between government department such as Telecom, Water Board and local authorities when repeatedly opening up roads to lay utility lines, Sooriyarachchi admits that this is something they are working to streamline immediately.
Referring to the recent flooding of newly rebuilt sections such as the Thummulla Junction, Sooriyarachchi explains that the recent rains were unprecedented. “This is rain intensity above design standards.” However he confides that the RDA is looking into design criteria both in fine print as in the form of physical checks. Referring to the tragic death of the young woman who fell into a drainage hole in Horton Place in 2007, Sooriyarachchi assures, “We are in the process of identifying critical points to avoid another incident like the one in Horton Place.”