Ambient groundwater

Groundwater present before MAR activity took place, quality not substantially influenced by MAR activities.

Anaerobic

A condition characterized by the absence of atmospheric oxygen

Anisotropy

A condition where one or more of the hydraulic properties of an aquifer vary according to direction

Artificial recharge

Historical expression describing groundwater replenishment usually by infiltration ponds or infiltration wells, might be misleading because it relies mostly on natural processes and only the recharge/infiltration is artificial or man-made, artificial recharge does not explicitly focuses on water quality.

ASR well

Well used for injecting water into an aquifer and subsequent abstraction from the same well.

Attenuation zone

Area surrounding the recharge zone where groundwater quality changes take place due to natural processes in the aquifer, groundwater quality changes due to straining, degradation, sorption, dissolution, precipitation, inactivation or die-off, redox reactions, decay and mixing, beyond the attenuation zone all environmental values (e.g. natural background concentrations) of the target aquifer are met.

Background values

Geogenic or anthropogenic chemical/physical/biological range of properties in groundwater representative for the aquifer.

Bank filtration

Usually refers to induced infiltration of surface water by pumping from a nearby well but can also occur naturally under losing river conditions.

Bulk density

The mass or quantity of a substance per unit volume

Baseline monitoring

Used to determine and document the current conditions.

Check dam

Temporary or permanent dam built across a stream/river channel to retain part of the discharge and enhance groundwater recharge, usually constructed in non-perennial rivers.

Confined aquifer

An aquifer that is overlain by a confining bed with a significantly lower hydraulic conductivity than the aquifer such that the hydraulic head in the aquifer is higher than the elevation of the top

of the aquifer

Disinfection

Removal or inactivation of pathogenic microorganisms.

Darcy´s law

The equation governing flow through a porous medium, velocity = hydraulic conductivity × gradient, or volumetric flow rate = hydraulic conductivity × gradient × area perpendicular to flow

Groundwater mounding

A mound of water in the ground formed by either a perched water table on a low hydraulic conductivity layer below localized infiltration, or a rise of the water table cause by localized infiltration

Heterogeneity

The spatial variation of properties within a material

Hydraulic impact zone

Zone of hydraulic influence of the MAR system.

Hydraulic loading

long term average infiltration rate characteristic for the site (in case of surface spreading)

Hydrochemical sampling

Withdrawal and conservation of water samples aimed to analyze certain chemical properties of the water.

Impacted water

Groundwater quality directly influenced by MAR activities, found in the attenuation zone.

Infiltration

Entry of fluids in porous media.

Losing river conditions

River water infiltrates due to lower hydraulic heads in the adjacent groundwater, common in arid areas, opposite to gaining river conditions

Managed aquifer recharge

Intentional recharge, storage, treatment of water in the subsurface for subsequent recovery or for environmental benefit.

Monitoring

Systematic sampling, measurement and documentation of indicators (e.g. water level, water quality).

Natural background level (NBL)

Chemical/physical/biological property of groundwater without any significant anthropogenic influence.

Natural Treatment System

Multi-objective treatment system employing natural processes and components (soil/aquifer, vegetation and sunlight) to improve water quality, includes constructed wetlands and MAR.

Operational monitoring

Used to determine and document impacts of operational practice.

Percolation

Movement of fluid through porous media.

Perched groundwater

A water saturated zone that is above the average water table, due to the occurrence of a lens or layer of low hydraulic conductivity

Post-treatment

Treatment step(s) to further improve quality of water after the MAR systems to meet the water quality standards/guidelines and regulations.

Pre-treatment

Treatment step(s) to improve quality of source water before employing MAR systems.

Recharge shaft/pit

Structures to enhance recharge through shafts/pits into unconfined aquifers which are overlain by low permeability geological layer.

Reclaimed water

former wastewater (sewage) that is treated to remove solids and impurities, and used to recharge aquifers.

Recovery rate

volumetric ratio between source water abstracted by the production well(s) and source water which is infiltrated.

Soil Aquifer Treatment

Infiltration and percolation of reclaimed water (treated wastewater) through soil and aquifer passage.

Source water

Water that is used as input water for MAR.

Target aquifer

Aquifer identified for managed recharge.

Total Suspended Solids

The measure of particulate matter suspended in a sample of water, which is determined by measuring the weight of dried residue after filtering a known sample volume.

Tracer

Natural/anthropogenic compound or physical property of water which allows the determination of flow paths and degree of mixing. The ideal tracer is widely distributed in the system, easy to detect and the geochemical behavior is conservative (non-reactive and non-retarding) or at least predictable (radioactive decay).

Unconfined aquifer (also water table aquifer)

Bounded below by an aquiclude, but not restricted by any confining layer above it

Ubiquitary

Commonly found in the environment.

Validation monitoring

Used to determine and document current conditions compared to e.g. baseline conditions.

Vadose zone

Unsaturated zone, or the zone between land surface and the water table where pores are filled with some air and some water

Water reuse

General term for the beneficial use of treated or reclaimed (waste-water).