Due to tens of millions of farmers’ irrigation programs in Bangladesh, there’s more room for monsoon water to go straight into aquifers, probably mitigating flooding


15 September 2022

An electric-powered irrigation well pumping groundwater to rice fields during the dry season in north west Bangladesh

An electrical-powered irrigation properly pumping groundwater to rice fields in the course of the dry season in north-west Bangladesh

M. Shamsudduha, UCL

Thousands and thousands of smallholder farmers in Bangladesh pump large quantities of groundwater for irrigation, serving to to triple the nation’s rice manufacturing and probably mitigate floods throughout monsoon season.

Intensive irrigation and different agricultural enhancements because the 1980s have enabled Bangladesh to provide sufficient meals annually to be practically self-sufficient. “In Bangladesh we rely closely on groundwater for irrigation,” says Kazi Matin Ahmed on the College of Dhaka in Bangladesh. He says Bangladesh has a number of groundwater however there are issues it might be depleted.

Utilizing tens of millions of groundwater measurements from 465 websites throughout Bangladesh, Ahmed and his colleagues estimated how a lot groundwater was pumped by greater than 16 million farmers between 1988 and 2018.

Collectively, the farmers function greater than 1 million diesel and electrical pumps to flood rice paddies in the course of the dry season, which has enabled extra meals to be produced on extra land. Due to irrigation and different agricultural enhancements, rice manufacturing within the 2018-2019 season was greater than triple what it was within the early 1970s.

At roughly 25 per cent of the websites, the data confirmed depleting groundwater ranges. At round 40 per cent ranges in the course of the dry season and monsoon remained regular. Within the remaining 35 per cent, ranges declined in the course of the dry season as a consequence of irrigation however aquifers had been utterly refilled in the course of the monsoon.

“In our a part of the world there’s a number of rainfall, there’s a number of river stream,” says Ahmed. “Not all of that may discover its strategy to the aquifers, as a result of they first grow to be full. When [farmers] extract extra groundwater, the water stage falls and it creates room for added recharge.”

This extra recharge amounted to between 75 and 90 cubic kilometres of freshwater captured between 1988 and 2018. That’s greater than twice as a lot as is held again by the Hoover Dam within the US. Divided throughout 30 years, the annual extra seize is bigger than the UK’s whole annual water use, says Mohammad Shamsudduha at College Faculty London.

Along with boosting yields, this “Bengal Water Machine”, because the researchers discuss with it, might have helped reduce flooding throughout monsoon seasons. “If there isn’t a recharge, all of the water could be on the floor. Then you have got an even bigger flood,” says Ahmed.

Pumping groundwater for irrigation is unsustainable in lots of locations. In northern India, the western US, northern China and different dry locations, pumping has depleted aquifers. Globally, most land irrigated previously twenty years is positioned in locations with out sufficient water to pump with out finally working dry.

However Bangladesh and different locations with the same geology and a seasonal monsoon, reminiscent of japanese India, Nepal and components of South-East Asia, may see these twin advantages of elevated meals manufacturing and flood safety from extra irrigation, says Aditi Mukherji on the Worldwide Water Administration Institute in India.

“What we don’t know sufficient is the long-term impression of local weather change,” she says. At the same time as irrigation helps farmers defend in opposition to local weather variability, extended drought or extra erratic rainfall patterns may change the dynamics that make such “water machines” run.

Journal reference: Science, DOI: 10.1126/science.abm4730

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