Managed Aquifer Recharge (MAR) has becomes a popular term in today’s water resources management for good reason. MAR’s driver is increased world water use. According to Water Consumption Statistics’ web site, where data are provided by the United Nations (UN, UNESCO, and FAO), agriculture accounts for 70% of all water consumption, compared to 20% for industry and 10% for domestic use. In industrialized nations, however, industries consume more than half of available water. Belgium, for example, uses 80% of available water for industry. Consumption is also increasing due to the world’s population growth. Annual growth of 80 million people has resulted in freshwater withdrawals tripling over the last 50 years.
Changes in lifestyles and eating habits in recent years have resulted in more water consumption per capital. Energy demand is also accelerating, with corresponding implications for water demand.
Managed aquifer recharge is one way to better use available water resources to satisfy high demand in recent years and to manage declining groundwater levels in aquifer, response better to contamination prone surface reservoirs and changes in climate. I was mentioning surface reservoirs and its vulnerability for contamination and just recently one surface reservoir in South East Europe, Serbia, reservoir Vrutci was experiencing algae bloom due to increase phosphorous concentrations in reservoir and the whole city of Uzice (about 70000 population) was left without water until emergency measurements were taken. Remediation in this and other cases is extremely difficult and costly.
According to lit.1, before 1970. year managing of water resources via artificial recharge in USA was seldom done, mostly surface water and reservoirs were used. It can be said that water demand was satisfied through conventional methods like well fields, dams, reservoirs and surface water usages. Artificial recharge was at starting stage at that time and it was common to think at that time that injection wells are inefficient due to clogging.
Artificial recharge of groundwater can be divided between surface recharge and well recharge (single purpose, injection wells). Surface recharge are suitable where soils are permeable to conduct water from surface recharge basins and where land can be obtained at affordable price for large areas of recharging basins. Usually, bottom of surface basins is clogged and periodical cleaning is necessarily to deliver water from surface to subsurface aquifer.
Injection wells (single purpose wells) were used in the past but it was observed that plugging of the well screens was common and that was reducing use of this kind of recharge.
Term ASR (Aquifer Storage Recovery) was coined by David Pyne (Lit 1) in 1983 and it describes the dual purpose wells where both recharge and pumping are going on from one well. ASR wells store water in suitable aquifers during wet months and other times when water is available, and recover the stored water from the same wells during droughts, peak demands, and other times when the stored water is needed. These ASR wells uses pumps to redevelop wells during pumping phase and they are less prone to clogging then single purpose (injection only) wells.
Aquifers can be divided in unconfined, semi confined and confined aquifers. Although all type of aquifers are possible to use with ASR wells unconfined aquifers are less suited for ASR wells (1).
On the figure 1 (Lit 3) it can be seen the development and increased usage of ASR well in USA
To apply ASR technology in management of water resources, as in other disciplines, phased approach is needed. First step is to see do we have enough water for injection during wet months and low demand to satisfy dryer conditions (usually during summer) with increasing water demand.
The next step is to asses are the hydrogeological conditions good enough to support ASR. These two points are usually a desktop study and should precede any of the field works.
This was a short introduction to ASR technique in MAR to raise awareness of this water resources management methodology and to direct interested parties toward the first steps that should be taken before any field and test programs.
In last several years, from 2012, with support of my USA colleagues, I was screening for suitable ASR (Aquifer Storage Recovery – dual purpose wells) sites in South East Europe. Huge amount of data was collected and analyzed to investigate where ASR can be applied and manage water resources effectively.
Dozens of projects were done where suitability for ASR application were investigate from hydrogeological point of view. Significant experience was achieved and I am ready to share it with you and your company.
Feel free to contact me for additional information about how to assess your hydrogeologyical conditions and decide can ASR be applied in your region.
More info you can find if you send me email, advancedgwt@gmail.com (I am still using gmail, got used to it)
Literature:
Pyne, R.D.G., Aquifer Storage Recovery: A Guide To Groundwater Recharge Through Wells (Second Edition), ASR Press, 2005 (608 pages)
Kaludjerovic D., Contribution to Management of Groundwater Sources With Dual Purpose Wells – ASR (Aquifer Storage and Recovery), Water Economy Journal, Belgrade, 2013. (on Serbian)