Impacts of Human Development and Climate Change on Groundwater Resources in Bangladesh

Abstract

Groundwater has been playing a central role in drinking and irrigation water supplies in Bangladesh for more than four decades. Today, nearly 97% of all drinking water supplies in Bangladesh come from groundwater via hand-operated tubewells that tap the shallow part (<150 m bgl) of the Bengal Aquifer System (BAS). Groundwater-fed irrigation, that currently meets 80% of irrigation water supplies, has been sustaining the dry-season high-yielding “Boro” rice cultivation since the 1970s that has made Bangladesh nearly self-sufficient in food production and led to major economic development. The shallow groundwater is, however, facing major challenges: (1) widespread, natural contamination of arsenic (As) and salinity in coastal areas and (2) rapid depletion of groundwater storage in intensely irrigated areas (e.g., Barind Tract) and major metropolitan cities like Dhaka City. Substantial declines in shallow groundwater levels are currently leading toward an “unsustainable” condition for low-cost pumping technologies (e.g., hand pumps, shallow irrigation wells) and threatening food security. In contrast, intensive dry-season abstraction has also led to increased groundwater recharge by enabling pumping-induced greater infiltrations of rain and surface water during the wet season in areas where surface geologies are permeable and potential recharge is high—realizing the idea of the Ganges Water Machine. Although the impacts of human development of groundwater resources are evident, it is unclear how changing climate will affect groundwater quality and quantity. In addition, recently, there is an increased focus on the development of deep groundwater in Bangladesh to mitigate As and salinity problems. However, little is known about recharge mechanisms and long-term security of the deep groundwater resource in Bangladesh.