Over the last five months, rain has been abnormally scarce in Bangladesh, leaving lands parched and flows of major rivers at a historic low.
Signs of drought are everywhere — in government-collected data, interrupted irrigation, burned-down rain forest, seawater moving further inland and the outbreaks of diseases related to low humidity or depleted water level.
The exceptionally dry spell is likely to continue for the sixth straight months through May, Bangladesh Meteorological Department has warned, with farmers complaining about disrupted crop growth because of low soil moisture.
‘A drought has clearly set in,’ M Shahjahan Mondal, who teaches water and flood management at BUET, told New Age.
He said there are four kinds of drought — meteorological, hydrological, agricultural and socio-economic.
Meteorological drought is dry weather with little rain and high temperature — a condition persistent since December last year with Bangladesh receiving 98.8 per cent less rain than the month’s normal average.
A month’s normal average rainfall is the 30 years average of rain received in the month. The current monthly average rainfall that BMD uses covers the period from 1970 to 2000.
Compared to their monthly normal averages, January witnessed 97.7 per cent less rain while February received 99.1 per cent less, March 80 per cent and April 79 per cent.
Absence of data stands in the way of understanding the historical frequency of droughts in Bangladesh.
Yet this is the first time in eight years that the first four months of a year had gone so dry.
In 2013, January was 93 per cent rain deficient, followed by February with 70 per cent deficiency, March with 80 per cent deficiency and April with 51 per cent deficiency.
‘Less rain in December, January, February and even March may be acceptable to many,’ said AKM Saiful Islam, professor at the Institute of Water and Flood Management, BUET.
‘But getting so little rain in April is highly abnormal and an indication of a meteorological drought,’ said Saiful, also an expert reviewer of IPCC’s special report on global warming of 1.5°C.
The drought comes on the heels of a prolonged flood last year, corroborating the proposition that the impacts of climate change would turn dry season drier and wet season wetter, he explained.
April can get very wet sometimes and its potential to trigger flash floods in the north-eastern region in the pre-monsoon season — March to May — prompted the government to develop a special flash flood warning mechanism.
In 2017, the year of the latest flash flood, the monthly cumulative rainfall in April stood at 10,900mm. Last year April recorded 4,343mm rain while the month received 7,468mm rain in 2018, 5,876mm in 2015, 947mm in 2014, 2,162mm in 2013 and 6,430mm in 2012.
But rainfall received this April was less than 1,000mm.
‘Winds responsible for bringing rain at this time of the year were largely absent,’ said meteorologist Bazlur Rashid.
Low evaporation in relatively cool Bay of Bengal caused a reduced supply of moisture as this April, historically known for cyclone, did not see a single low pressure form, he explained.
On the first day of May, flows of major north-eastern rivers fell historically low, with 15 out of 26 river gauge stations breaking four to six decades of records, the Water Development Board data showed.
Seven of the river gauge stations along the Kushiyara, the Someswari, the Sarigowain, the Bhogai-Kangsha and the Surma rivers recorded the lowest flow in 63 years.
Six other river gauge stations along the Bhogai-Kangsha, the Dhalai, the Manu, the Kalni, and the Kshiyara rivers broke 53 years record of low flow.
Two stations along the Surma and the Dhanu-Boulai rivers recorded the lowest flow in 43 years.
At the beginning of May, the River Jamuna flow fell to 33 years low at Bahadurabad point while the flow of Brahmaputra fell to 22 years low at Chilmari.
The Padma recorded its lowest flow in 27 years at Bhagyakul at the beginning of May.
The other rivers that also recorded the lowest flow in 33 years included the Teesta, the Sangu, the Halda and the Ganges.
The water level in Ganges fell so low that the Ganges-Kobadak irrigation project had to be halted twice in March and April affecting boro cultivation.
In April, diarrhoea killed at least 12 people in the southern Bangladesh division of Barishal alone in an outbreak the kind of which was not seen in recent time.
Public health experts directly linked the diarrhoea outbreak to water level depletion increasing contaminant concentration and salinity in water.
In April, rice fields in over half of Bangladesh also felt an unprecedented heat shock affecting 3 lakh farmers in 36 districts.
The heat shock prompted advisories asking farmers to keep their rice fields hydrated but they were already hard-pressed for water.
Groundwater level fall, particularly in northern and parts of central Bangladesh, had already made its rounds in the news by April.
Biodiversity and ecology researcher Pavel Partha said that farmers in Satkhira was complaining about low soil moisture hampering the germination of crops such as pumpkin, wax gourd and bitter gourd.
The absence of moisture turned soil in areas such as Chattogram, Sylhet and Madhupur as hard as stone, making even the collection of traditional food such as wild yam very difficult, said Partha.
‘The late April fire that burned 1.5 acres of rainforest in Lawachhara is the most glaring example of how dry and crispy the land has become,’ said Partha.
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