Bangladesh sees 75% excess April rainfall; flood risks rise in haor regions

Bangladesh recorded 75% above-normal rainfall in April, fuelled by multiple western depressions, while six river stations in northeastern haor regions exceeded pre-monsoon danger levels, meteorologists and flood forecasters said today (2 May).

Meteorologist Bazlur Rashid of the Bangladesh Meteorological Department told The Business Standard that April rainfall was highly abnormal, persisting for 8-10 days instead of the usual 2-4 days.

"Winter rainfall, which typically occurs between December and April, is triggered by western depressions originating over the Mediterranean. These systems move eastward, split over Iran and Kashmir, and one branch eventually reaches Bangladesh," he said.

"This year, after the last rainfall in November, the country experienced another spell only in the second week of March. The extended dry period intensified the depression systems. Normally, one or two such systems develop each month, but several arrived simultaneously in April. By contrast, April 2024 was dominated by a prolonged heatwave," he added.

According to the Met office's five-day forecast, rainfall is likely to continue across the country due to an active depression stretching from West Bengal to the northern Bay of Bengal.

A bulletin signed by meteorologist AKM Nazmul Haque said that from 9am on 2 May, light to moderate rain or thundershowers accompanied by gusty winds may occur in many areas of Mymensingh, Dhaka, Barishal, Chattogram and Sylhet divisions, and in parts of Rangpur, Rajshahi and Khulna.

Moderate to very heavy rainfall is expected in some areas of Mymensingh, Chattogram and Sylhet, while day and night temperatures may remain largely unchanged. Similar weather conditions are forecast for 3 and 4 May.

On 5 May, rainfall may continue in many parts of Khulna, Barishal and Chattogram, with scattered showers elsewhere and a slight rise in temperature. On 6 May, rain is likely in most divisions, though rainfall may gradually decrease over the extended five-day period as temperatures rise further.

Meanwhile, the Flood Forecasting and Warning Centre (FFWC) of the Bangladesh Water Development Board reported that water levels at six monitoring stations on five rivers in Sunamganj, Netrakona and Habiganj have risen above pre-monsoon danger levels.

These include the Naljur River at Jagannathpur, Bhugai-Kangsa at Jaria Jhanjail, Someshwari at Kalmakanda, Magra at Netrakona and Atpara, and Sutang at the Subhang railway bridge point.

Over the past 24 hours, water levels in the Surma and Kushiyara rivers remained stable, Bhugai-Kangsa declined slightly, while Dhanu-Baulai rose marginally. Moderate to heavy rainfall was recorded upstream, with haor areas receiving heavy to very heavy rain. Similar rainfall intensity is forecast over the next three days.

The FFWC warned that water levels in the Surma-Kushiyara river system may rise further in Sylhet and Sunamganj, with the Kushiyara likely to cross danger levels at certain points by the third day, potentially flooding adjacent low-lying areas.

Bhugai-Kangsa and Someshwari rivers may remain stable, prolonging existing flooding in parts of Netrakona.

Dhanu-Baulai is expected to rise further, with the Baulai River at Khaliajhuri likely to cross danger levels within 48 hours.

In Habiganj and Moulvibazar, water levels in the Khoai, Sutang, Manu and Juri rivers are also expected to rise. The Khoai and Juri may exceed danger levels within 24 hours, while the Manu may remain near warning levels, increasing flood risks in haor regions and worsening conditions in Habiganj.