Assessment of the Managed Aquifer Recharges (MAR) Constructed from 2009 to 2018 in the Pleistocene Geological Formation Areas of Bangladesh

After independence in 1971, Bangladesh started to extract extensive groundwater for drinking sources driven by the need for bacteriologically safe sources for public health protection, as a result currently about 98% of the population relies on groundwater for drinking purposes. About 77% of the current irrigation coverage is provided through groundwater sources. 1500 billion litres of groundwater have been extracted annually for the textile industry backyard of the Ready-Made Garment sector. Consequently, significant groundwater depletions are taking place in the Pleistocene geological formation areas along with its surrounding floodplain areas because of the thick top clay layer that limits the natural recharge of groundwater.

To address the groundwater recharge by rainwater both from rooftop and surface runoff, Managed Aquifer Recharge (MAR) is one of the options. In this regard, in 2021 the Bangladesh Water Development Board along with Water Resources Group has drafted the MAR Strategy, yet to be finalized.

For learning and introducing the MAR in Bangladesh some organizations have constructed a few numbers of this technology, some of them are still functioning and some are abandoned. The study team assessed MAR technologies located in Dhaka and Rajshahi Divisions mainly in the Pleistocene geological formation areas constructed by government agencies and non-government organizations. In addition, the study team reviewed the country’s policy, strategy, guidelines and journals and conducted interviews with professionals and academicians at home who are associated with MAR technology to get the facts that are associated with the functionality and non-functionality of MAR.

From this study’s findings, two significant points have been picked up for MAR’s sustainability and better functioning, one is turbidity control of the collected rainwater and another is lithology for having the information of saturated, moderately saturated and unsaturated aquifer zones because of choosing the layer where rainwater is to be penetrated for storage or replenish. Routine maintenance is compulsory for turbidity control as well. In addition, as the rain pattern has already changed, torrential rainfall within a very short time has been happening due to climate change which creates water logging in urban areas that could be partially resolved if MAR scales up significantly, the study team assessed it as well.