In the face of growing water insecurity, the search for solutions to sustain and revitalize natural water resources is key. Managed Aquifer Recharge (MAR) is emerging as one such solution to bolster storage, enhance availability, and fortify groundwater resources. Here, we explain some of the basics of MAR and highlight examples of current MAR projects from around the world.
Managed aquifer recharge (MAR), also known as groundwater replenishment, water banking, and artificial recharge, is a technique that involves intentionally introducing water, typically river water, treated wastewater, or stormwater, into an aquifer to increase its storage and availability. Alongside demand management efforts, MAR is an increasingly important strategy to protect groundwater systems and improve water quality.
Research suggests, however, MAR is currently an underutilized solution globally. Data published in 2019 showed that implementation of MAR accounted for around 2.4% of groundwater extraction in countries reporting MAR, although experts predict MAR could exceed 10% of global extraction in the future.
The implementation of MAR schemes is influenced by several factors including the area’s hydrogeology, available water sources, regulatory frameworks and local water management priorities – all of which impact the specific recharge method and costs.
Barriers to implementation include the need for funding and/or investment in infrastructure, including wells, infiltration basins, pipelines, and treatment facilities, as well as technical expertise, sufficient land space, and proper site selection – as not all aquifers are suitable for MAR. Success depends on careful planning, monitoring, and adaptive management to mitigate potential risks and maximize its benefits.
There are, however, interesting examples of MAR in action, with a variety of benefits. The International Groundwater Resources Assessment Centre (IGRAC) has compiled a portal listing more than 1,200 MAR sites globally. Deeper exploration shows diverse contexts in which MAR is applied, ranging from addressing water scarcity in arid regions to managing groundwater in more temperate climates.
New innovations, including remote sensing and GIS modeling, advances in drilling techniques and well design, and new water treatment technologies are improving the efficiency, effectiveness, and sustainability of recharge projects. As climate change continues to alter precipitation patterns and demand for water increases, we can expect the use of MAR to continue to grow.
Here are a few examples of MAR projects from across the globe.
California is home to several MAR projects. One is the Chino Basin Recycled Water Groundwater Recharge Program, which consists of a network of pipelines that direct stormwater run-off, imported water, and recycled water to 16 recharge sites with basins spread across 245 square miles. Water percolates into the ground, with the soil acting as a natural filtration system, to replenish the groundwater supply.
In Berlin, a water supply region serving a population of 3.6 million, around 75% of drinking water is produced using bank filtration and MAR.
Water is pumped from wells drilled along the banks of a river. During the pumping process, river water infiltrates into the riverbed sediments and is naturally purified.
The MENA region is the world’s most water-scarce region with only two percent of the global average annual rainfall, high rates of pumping and low rates of natural aquifer recharge. Oman, however, has the highest groundwater renewability in the GCC countries (76%), thanks in part to more than 50 recharge dams which store runoff water from streams. The dams help raise the water level in wells and irrigation systems, support farmers and livestock breeders, and increase water sources.
Brazil is home to more than 60% of Latin America’s MAR projects. Most projects include in-channel modifications, specifically subsurface dams. The dams help store water used for food production within poorer communities. Infiltration ponds and basins are also used to prevent soil erosion and produce food in rural areas and to support drainage and prevent flooding in urban areas.
outh Africa has the highest MAR implementation rates on the African continent. One long-standing example is the Atlantis Water Resource Management Scheme (AWSS). It began recharging stormwater and treated wastewater into the soil in the 1970s as an alternative to marine wastewater discharge.
Now, 12 stormwater retention and detention basins capture stormwater from the residential and industrial areas. Industrial stormwater is also separated from residential stormwater to enable the highest quality water to reach the most critical areas.
In Uttar Pradesh, underground taming of floods for irrigation (UTFI) was trialed as a means of improving water resiliency in advance of dry spells.
In a pilot project, an unused pond was retrofitted with 10 gravity recharge wells to store excess water from the Ramganga Basin during the wet season. Over two years, the pond recharged up to 14 times its capacity and provided enough water to irrigate roughly 15 hectares of farmland.
With long, dry summers and steadily declining rainfall, Perth’s Water Corporation initiated a plan back in 2010 to treat recycled water from the Beenyup Wastewater Treatment Plant to beyond drinking water standards and inject it into the Leederville and Yarragadee aquifers.
Since then, the scheme has recycled around 60 billion liters of water. Recently, the government launched a $320 million expansion of the scheme to double long-term capacity and provide enough water to supply up to 100,000 households.