Nine waves of flash floods hit Bangladesh in the past five months, affecting millions, many of them repeatedly, according to a presentation made by the Flash Flood Warning Centre at a discussion on Wednesday.
The first wave lasted between May 28 and June 7 in northeast, followed by the second wave occurring between June 15 and 16 in parts of north and northeast.
The third wave swept through north, northeast and southeast regions between June 30 and July 16.
The fourth wave lasted between August 1 and 3 in the Matamuhuri, Halda, Muhuri and Feni river basins, followed by the fifth wave occurring in the Surma-Kusiyara basin between August 7 and 13.
The sixth wave of the flash flood hit on August 19 in eight river basins in northeast and southeast Bangladesh and lasted until the 27th of the month.
The seventh wave hit parts of southeast on September 23, followed by the eighth wave sweeping through the Teesta basin between September 28 and 29.
The final wave hit north and northeast between October 4 and 7, according to the presentation prepared by Sarder Udoy Raihan, executive engineer, FFWC.
Some of the flash floods exposed Bangladesh鈥檚 disaster management loopholes highlighting the danger to which people are exposed to because of India sharing limited information on common rivers.
For instance, the flash flood in mid-August caught Bangladesh completely off-guard. The flood was triggered by heavy rainfall over vast swathes of land across borders. The extreme rainfall occurred over hills from where water enters Bangladesh as fast as in one hour.
The rainfall was caused by a low pressure that changed its course at the last moment heading for Bangladesh.聽
A review of the rainfall data from August 16 to 22 shows that during the period, the Muhuri River basin and adjacent areas received about 500 mm. The average daily rainfall record for the period is 50-65 mm.
The Muhuri River flooded three times in August alone.
鈥楴atural disaster frequency is clearly increasing,鈥� said AKM Saiful Islam, a professor at the Water and Flood Management department of Bangladesh University of Engineering and Technology.
The discussion was organised by the Bangladesh Meteorological Department and Regional Integrated Multi-hazard Early Warning System.
Saiful pointed out that the nature of flood was changing.
With a degree Celsius rise in temperature, rainfall picks up by seven per cent, he said.
Heavy rain in the small-scale watershed is increasing, leading to flash floods.
The speakers at the programme said that land management exacerbated floods.
The BMD also provided a seasonal outlook for the winter season, which begins in November, predicting that the winter season is also going to be rather warm.