Stable groundwater quality in deep aquifers of Southern Bangladesh: The case against sustainable abstraction

Abstract

In forty six wells >150 m deep, from across the arsenic-polluted area of south-central Bangladesh, groundwater composition remained unchanged between 1998 and 2011. No evidence of deteriorating water quality was found in terms of arsenic, iron, manganese, boron, barium or salinity over this period of 13 years. These deep tubewells have achieved operating lives of more than 20 years with minimal institutional support. These findings confirm that tubewells tapping the deep aquifers in the Bengal Basin provide a safe, popular, and economic, means of arsenic mitigation and are likely to do so for decades to come. Nevertheless, concerns remain about the sustainability of a resource that could serve as a source of As-safe water to mitigate As-pollution in shallower aquifers in an area where tens of millions of people are exposed to dangerous levels of arsenic in well water. The conjunction of the stable composition in deep groundwater and the severe adverse health effects of arsenic in shallow groundwater lead us to challenge the notion that strong sustainability principles should be applied to the management of deep aquifer abstraction in Bangladesh is, the notion that the deep groundwater resource should be preserved for future generations by protecting it from adverse impacts, probably of a minor nature, that could occur after a long time and might not happen at all. Instead, we advocate an ethical approach to development of the deep aquifer, based on adaptive abstraction management, which allows possibly unsustainable exploitation now in order to alleviate crippling disease and death from arsenic today while also benefiting future generations by improving the health, education and economy of living children.