Managed Aquifer Recharge (MAR) involves purposefully recharging groundwater, commonly using treated effluent, stormwater, or excess surface water, often through infiltration or injection. MAR helps mitigate risks from climate change and population growth while providing water for reuse and environmental benefit.
As Earth’s climate changes, more extreme weather conditions are experienced globally. From record-breaking heat waves on land and in the ocean, drenching rains, severe floods, years-long droughts, extreme wildfires, to widespread flooding during hurricanes, extreme weather events are all becoming more frequent and more intense. The practice of MAR and improving water resource resilience is a useful tool in mitigating a number of risks facing humanity due to climate change.
Water supply and food production protection
By augmenting aquifers through MAR groundwater supply security is improved and groundwater abstraction can generally continue during prolonged drought periods so long as MAR source water remains available. In this case the use of treated effluent is an excellent MAR source water. When using excess surface water as MAR source water it is also protected against evaporation losses.
With ~40% of global agriculture relying on unsustainable groundwater abstraction, water security risks are heightened, especially with increasing droughts and population growth. This risk to global food production potential can be mitigated somewhat through the practice of MAR by the global agricultural sector.
Saline water intrusion and contamination barriers
Coastal aquifers from which groundwater is abstracted for supply are at risk of saline water intrusion (SWI) due to over-pumping and sea level rise. MAR through injection or infiltration as a subsurface SWI barrier ensures that coastal aquifer quality can be maintained. Because this process is not for the augmentation of aquifers for groundwater supply, it is usually poorer quality water (not suitable for groundwater supply MAR) that is used in SWI’s. This process provides a secondary service as a scheme outfall.
Similarly, MAR can be used to protect groundwater abstraction schemes from known sources of groundwater contamination. This is particularly useful in peri-urban area’s underlain by shallow unconfined aquifers where a high groundwater contamination risk from surface land uses exists. In such cases contamination barriers can be established to change the flow path of groundwater contaminants away from groundwater production areas.
Flood mitigation
Flood mitigation through MAR can be implemented where aquifers occur adjacent to natural drainage systems which regularly burst their banks through in-channel diversion points. In urban areas with formal stormwater drainage systems, the development of stormwater detention basins is a useful addition to retard very high stormwater flow. The featured image of this article was taken at a MAR basin in the Western Cape of South Africa during the recent July to August 2024 floods that the area experienced.
If you would like more information on the benefits of MAR or if you’re interested in developing a MAR scheme contact Umvoto for assistance and/or additional information.
