Bengaluru: Groundwater around the world is depleting at a rapid rate and is, in turn, affecting the flow of rivers and streams, a new study has found.
The study collected data beginning from 1960 and made projections on the impact of unfettered groundwater pumping until the year 2100.
The results show that unsustainable groundwater pumping for irrigation exceeds the rate of replenishment and leads to huge losses in agriculture-intensive societies, such as parts of India. Loss of groundwater results in loss of flow of water into rivers, potentially destroying aquatic ecosystems.
The study states that by 2050, up to 79% of all watersheds — large areas where water is naturally stored from rain and ice-melt — will be pumped beyond sustainability. This will lead not just to large-scale disruptions in aquatic ecosystems but also global food security.
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An already critical situation
This study, published in the journal Nature this week, is the first to model and simulate the impact of groundwater depletion on other water-bodies such as rivers, lakes, and wetlands.
It also revealed that river flows in over 20% of all regions where groundwater is pumped are already too weak to sustain healthy ecosystems. Areas where such depletion has already occurred include the Upper Ganges and Indus basins in India.
In another three decades, at least half of the watersheds in the world would cross their critical threshold of sustainability. This will be further exacerbated by increasingly hot and dry conditions due to the ongoing climate emergency.
Increased reliance of irrigation on groundwater in these regions will speed up the process. Tropical regions such as Asia, Africa, Southern Europe, and parts of Canada and Australia, are expected to be the worst affected.
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Additional effects of groundwater depletion include subsidence — a sudden sinking of a chunk of land. This leads to the land’s height above sea level to drop, which increases the risk of floods. Coastal cities like Chennai and Mumbai are already at risk, as they are running out of drinking water and groundwater is being pumped vigorously, as a result.
As water levels under the ground drop, pumping water becomes more expensive,
causing food prices to skyrocket and threatening economies.
Decrease in groundwater disproportionately affects the underprivileged during drought and dry season. Additionally, drying up of said water bodies slowly erodes the natural landscape and terrestrial ecosystems that come with it.
Changes in both terrestrial and aquatic ecosystems will travel up the food chain and directly affect humans in the form of fishing industries being hit hard, loss of birds — which will cause an increase in pests that would destroy crops, attraction of newer predators etc.
The authors of the study also state that these estimates are possibly optimistic, as the projection did not consider increase in groundwater demand due to population growth or the development of resource-intensive, emerging economies around the world in the near future.