Water securityWith floods and droughts increasing, communities take a new look at storing water underground

By Erica Gies

Published 17 June 2019

Groundwater recharging – that is, actively moving water underground, a practice known as managed aquifer recharge (MAR) — is the latest wave in water security. There are about 1,200 managed aquifer recharge projects in 62 countries. MAR can be used to restore depleted aquifers, rehabilitate ecosystems and cleanse polluted water. But there are challenges as well.

Houston, Texas, has flooded every year for the past five years. At the same time, Texas is also known for dire water shortages. What if people were to capture the floodwater and store it for later in aquifers — underground layers of permeable rock, gravel and sand that allow water to pass through?

A recent study by researchers from the University of Texas at Austin found that coastal aquifers from which water has been pumped for use in farms and cities, have enough space to store two-thirds of the water from high-flow events from 10 Texas rivers, reducing the impacts of both floods and droughts — if we figure out a way to get the excess water into them.

Actively moving water underground, a practice known as managed aquifer recharge (MAR), is increasingly popular today. There are about 1,200 managed aquifer recharge projects in 62 countries, according to the International Groundwater Resources Assessment Centre (IGRAC) based in Delft, the Netherlands. In addition to helping manage water over- and under-supplies, MAR can be used to restore depleted aquifers, rehabilitate ecosystems and cleanse polluted water. But there are challenges as well.

Water in the bank
Storing water underground for future use is increasingly popular due to growing volatility in supply because of climate change as well as to the downsides of the alternative: damming rivers to create surface reservoirs.

For one thing, in developed countries, many rivers are already dammed. For another, dams cause myriad environmental problems, such as preventing sediment from replenishing coasts, blocking fish migrations, and destroying river habitat by slowing down water and allowing it to warm. Reservoirs lose up to a quarter of stored water to evaporation, and sometimes have to release water to make room for big storms. And surface storage can lead to overuse of water because the sight of it gives people a false sense of water security. It also costs around double the price of groundwater recharge.