Farmers in Bangladesh pump so much water it may help reduce floods

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Thanks to millions of farmers’ irrigation systems successful Bangladesh, determination is much abstraction for monsoon h2o to spell consecutive into aquifers, perchance mitigating flooding

Environment 15 September 2022

By James Dinneen

An electric-powered irrigation good pumping groundwater to atom fields during the adust play successful northbound westbound Bangladesh

Millions of smallholder farmers successful Bangladesh pump immense amounts of groundwater for irrigation, helping to triple the country’s atom accumulation and perchance mitigate floods during monsoon season.

Intensive irrigation and different cultivation improvements since the 1980s person enabled Bangladesh to nutrient capable nutrient each twelvemonth to beryllium astir self-sufficient. “In Bangladesh we trust heavy connected groundwater for irrigation,” says Kazi Matin Ahmed astatine the University of Dhaka successful Bangladesh. He says Bangladesh has a batch of groundwater but determination are concerns it could beryllium depleted.

Using millions of groundwater measurements from 465 sites crossed Bangladesh, Ahmed and his colleagues estimated however overmuch groundwater was pumped by much than 16 cardinal farmers betwixt 1988 and 2018.

Together, the farmers run much than 1 cardinal diesel and electrical pumps to flood atom paddies during the adust season, which has enabled much nutrient to beryllium produced connected much land. Thanks to irrigation and different cultivation improvements, atom accumulation successful the 2018-2019 play was more than triple what it was successful the aboriginal 1970s.

At astir 25 per cent of the sites, the records showed depleting groundwater levels. At astir 40 per cent levels during the adust play and monsoon remained steady. In the remaining 35 per cent, levels declined during the adust play owed to irrigation but aquifers were wholly refilled during the monsoon.

“In our portion of the satellite determination is simply a batch of rainfall, determination is simply a batch of stream flow,” says Ahmed. “Not each of that tin find its mode to the aquifers, due to the fact that they archetypal go full. When [farmers] extract much groundwater, the h2o level falls and it creates country for further recharge.”

This further recharge amounted to betwixt 75 and 90 cubic kilometres of freshwater captured betwixt 1988 and 2018. That is much than doubly arsenic overmuch arsenic is held backmost by the Hoover Dam successful the US. Divided crossed 30 years, the yearly further seizure is greater than the UK’s full yearly h2o use, says Mohammad Shamsudduha astatine University College London.

In summation to boosting yields, this “Bengal Water Machine”, arsenic the researchers notation to it, whitethorn person helped lessen flooding during monsoon seasons. “If determination is nary recharge, each the h2o would beryllium connected the surface. Then you person a bigger flood,” says Ahmed.

Pumping groundwater for irrigation is unsustainable successful galore places. In bluish India, the occidental US, bluish China and other adust places, pumping has depleted aquifers. Globally, astir land irrigated successful the past 2 decades is located successful places without capable h2o to pump without yet moving dry.

But Bangladesh and different places with a akin geology and a seasonal monsoon, specified arsenic eastbound India, Nepal and parts of South-East Asia, could spot these dual benefits of accrued nutrient accumulation and flood extortion from much irrigation, says Aditi Mukherji astatine the International Water Management Institute successful India.

“What we don’t cognize capable is the semipermanent interaction of clime change,” she says. Even arsenic irrigation helps farmers support against clime variability, prolonged drought oregon more erratic rainfall patterns could alteration the dynamics that marque specified “water machines” run.

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