The data-driven tool provides support in the selection of suitable MAR methods based on the analysis of several hundreds of MAR case studies worldwide.
The mehod selection tool aids the user in choosing a suitable MAR method for given characteristics defining the desired MAR site. There are manifold MAR methods available and several schemes exist to classify these methods. This tool is based on the classification system developed by IGRAC (IGRAC, 2015) and has been slightly adapted (Table 1). Selecting an appropriate MAR method for given conditions is often driven by two main factors: a suitable aquifer and an available suitable water source. If these two factors are given, MAR can generally be applied. Choosing the most appropriate method for the given local conditions is key in order to develop, operate and maintain and efficient and economic MAR project.
Table 1. Classification of MAR methods (adapted from IGRAC, 2015)
| Main MAR methods | Specific MAR methods | |
| Techniques referring primarily to getting water infiltrated | Spreading methods | Infiltration ponds (SAT) |
| Flooding | ||
| Ditches and furrows | ||
| Excess irrigation | ||
| Induced bank infiltration | River/lake bank filtration | |
| Dune filtration | ||
| Well, shaft and borehole recharge | ASR/ASTR | |
| Shallow well/shaft/pit infiltration | ||
| Techniques referring primarily to intercepting the water | In-channel modifications | Recharge dams |
| Subsurface dams | ||
| Sand dams | ||
| Channel spreading | ||
| Runoff harvesting | Rooftop rainwater harvesting | |
| Barriers and bunds | ||
| Trenches |
The selection of a MAR method is influenced by hydrologic and hydrogeologic factors such as geology, soil infiltration capacity, available water quantity and quality. Further important measures are the available land and cost.
Though the selection of an appropriate MAR method is very case specific, the tool at hand is giving the user a very rough first idea about which methods can be applied to a site with certain characteristics. Basis of the tool was a literature study comparing different MAR methods and characteristics to which they have been applied. Though more criteria might be applied to choose an appropriate method, for this tool five criteria were chosen as information on these characteristics was widely available.
Source of water
- Ephemeral rivers
- Perennial rivers
- Groundwater
- Runoff (rural, floods)
- Runoff (urban)
- Storage dams
- Treated waste water
If several sources of water are available, it might be noteworthy that they differ significantly in their quantity, reliability and quality (Table 2). These considerations have been already applied to the tool at hand. Some general considerations to note are that the quality of the source water can always be adjusted – raising the cost of the scheme! The quantity itself is most significant in terms of fluctuations, as large quantities of water might need to be handled in a short amount of time.
Table 2. Influence of source water on MAR scheme (Department of Water Affairs, 2010)
| Source of water | Quantity | Reliability | Quality |
| Perennial rivers | Variable | Variable | Variable |
| Ephemeral rivers | Variable | Variable | Variable |
| Dams | Variable | High | Low – high |
| Treated wastewater | Consistent | High | Low – high |
| Groundwater | Consistent | High | Consistent |
| Urban storm water | Variable | Variable | Variable |
| Rooftop runoff | Variable | Variable | High |
| Agricultural return flow | Variable | High | Low |
Soil type
- Highly clayey soils
- Shallow soils, clay soils, soils low in organic matter
- Sandy loams, silt loams
- Deep sands, well aggregated soils
The soil infiltration capacity is often the limiting factor at a proposed location as it defines the type (surface/subsurface) and size of the recharge site. A high conductivity is desirable for surface infiltration techniques, thus the surface infiltration capacity should be above 0.1 m/d (Bouwer, 1987). The soil type classification above is based on CGWB (2007) and introduces four iniltration classes. Infiltration classes “Medium” or “High” are required for surface infiltration techniques.
Table 3. Infiltration rates for different soil types (after CGWB,2007)
| Class | Soil infiltration rate (m/d) | Soil types |
| Very low | < 0.06 | Highly clayey soils |
| Low | 0.06 – 0.3 | Shallow soils, clay soils, soils low in organic matter |
| Medium | 0.3 – 0.6 | Sandy loams, silt loams |
| High | > 0.6 | Deep sands, well aggregated soils |
Land use
- Agricultural
- Barren Land
- Residential
- Industrial
- Recreational
- Streambed
The land use type classification is based on the Corine classification (Büttner et al. 2004) but adapted to fit the requirements of MAR sites. Land use types where no MAR is applied are left out while others are grouped.
Purpose
- Maximize storage capacity
- Prevent saltwater intrusion
- Restore groundwater levels
- Improve water quality
- Agriculture
- Domestic
- Ecological benefit
Typical scale
- Small (Household)
- Medium (Village)
- Large (Town)
Scale refers to the amount of people that the user wants to supply with the water stored by applying MAR. So roughly it is an estimate of the quantity of water to be stored. Even though most MAR types can be adapted to any of those scales, it is thought to represent the scale that MAR methods are mostly used for.
The user is asked to choose one or more suitable characteristics for each criterion, if the data is available to him. The tool will show all MAR methods applicable to the given characteristics in real-time. This means that if two types of source water are choosen, the resulting MAR types are either applicable for source type water 1 or source type water 2 or both. Please note that this tool only generates information on which techniques are feasible, it does not rank which ones are the most feasible or which ones have been applied the most to a specific situation!
To differentiate further the user is also provided with a very rough analysis on the cost and land need for each MAR method that is applicable to the specified situation. This is, however, only a tendency. The cost of a MAR scheme depends on many factors (scale, labor cost, pretreatment, …) so that it very much varies from scheme to scheme.
Example
REFERENCES
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- Bouwer, H. (1987). Design and Management of Infiltration Basin for Artificial Recharge of Groundwater. In 32nd Annual New Mexico Conference on Ground Water Management, Albuquerque, NM. http://www.wrri.nmsu.edu/publish/watcon/proc32/Bouwer.pdf.
- Büttner, G., Feranec, J., Jaffrain, G., Mari, L., Maucha, G., & Soukup, T. (2004). The CORINE land cover 2000 project. EARSeL eProceedings, 3(3), 331-346
- CGWB (2007) Manual on Artificial Recharge of Ground Water. Faridabad, India: Central Ground Water Board – Ministry of Water Resources – Govt. of India.. cgwb.gov.in/documents/Manual%20on%20Artificial%20Recharge%20of%20Ground%20Water.pdf.
- Department of Water Affairs (2010). Water Banking: A Practical Guide to Using Artificial Groundwater Recharge. Strategy and Guideline Development for National Groundwater Planning Requirements.
- IGRAC (International Groundwater Resource Assessment Centre) (2015). Global Inventory of Managed Aquifer Recharge (MAR) Schemes. https://ggis.un-igrac.org/ggis-viewer/viewer/globalmar/public/default.