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Application of GIS-based multi-criteria analysis for site selection of aquifer recharge with reclaimed water

Pedrero, Francisco, Albuquerque, António, Marecos do Monte, Helena, Cavaleiro, Victor, Alarcón, Juan José
Resources, conservation, and recycling 2011 v.56 no.1 pp. 105-116
aquifers, basins, constructed wetlands, drying, geographic information systems, groundwater contamination, heavy metals, monitoring, multi-criteria decision making, nutrients, pathogens, recycling, risk, rural areas, sand, texture, thematic maps, wastewater, wastewater treatment, water table, Portugal
Reclaimed water from small wastewater treatment facilities in the rural areas of the Beira Interior region (Portugal) may constitute an alternative water source for aquifer recharge. A 21-month monitoring period in a constructed wetland treatment system has shown that 21,500m³year⁻¹ of treated wastewater (reclaimed water) could be used for aquifer recharge. A GIS-based multi-criteria analysis was performed, combining ten thematic maps and economic, environmental and technical criteria, in order to produce a suitability map for the location of sites for reclaimed water infiltration. The areas chosen for aquifer recharge with infiltration basins are mainly composed of anthrosol with more than 1m deep and fine sand texture, which allows an average infiltration velocity of up to 1md⁻¹. These characteristics will provide a final polishing treatment of the reclaimed water after infiltration (soil aquifer treatment (SAT)), suitable for the removal of the residual load (trace organics, nutrients, heavy metals and pathogens). The risk of groundwater contamination is low since the water table in the anthrosol areas ranges from 10m to 50m. On the other hand, these depths allow a guaranteed unsaturated area suitable for SAT. An area of 13,944ha was selected for study, but only 1607ha are suitable for reclaimed water infiltration. Approximately 1280m² were considered enough to set up 4 infiltration basins to work in flooding and drying cycles.