###### Abstract  
Water percolation through infiltration ponds is creating significant synergies for the broad adoption of water reuse as an additional non-conventional water supply. Despite the apparent simplicity of the soil aquifer treatment (SAT) approaches, the complexity of site-specific hydrogeological conditions and the processes occurring at various scales require an exhaustive understanding of the system's response. The non-saturated zone and underlying aquifers cannot be considered as a black box, nor accept its characterization from few borcholes not well distributed over the area to be investigated. Electrical resistivity tomography (ERT) is a non-invasive technology, highly responsive to geological heterogeneities that has demonstrated useful to provide the detailed subsurface information required for groundwater modeling. The relationships between the electrical resistivity of the alluvial sediments and the bedrock and the difference in salinity of groundwater highlight the potential of geophysical methods over other more costly subsurface exploration techniques. The results of our research show that ERT coupled with implicit modeling tools provides information that can significantly help to identify aquifer geometry and characterize the saltwater intrusion of shallow alluvial aquifers. The proposed approaches could improve the reliability of groundwater models and the commitment of stakeholders to the benefits of SAT procedures. a +
Footnote †: journal: Applied Sciences  
article  
[color=gray!20, color=black]0  
0
Footnote 0: _Applied Sciences_  
0
Footnote 0: _Applied Sciences_  
+++ ==WARNING: Truncated because of repetitions==
etext: _Applied Sciences_  
0  
0
Footnote 0: These effects are especially visible in small unconfined aquifers because of their greater exposure to human impacts and smaller storage capacity, which may limit a regular water provision to ecosystems during drier periods. They will require efficient adaptations at the scale of the municipality or group of municipalities to supply the demand, to deal with the expected more irregular periods of rain, a decrease of aquifer recharge, and to manage wastewater properly. The most obvious is the provision of an alternative water resource and the second is the reduction of environmental impacts by reducing or eliminating wastewater disposal, which results in the preservation of ecosystems downstream [8]. To address these water resilience challenges, managed aquifer recharge schemes using recycled water have been utilized during the last few decades [9]. Water reuse is thus a means for increasing water resources and the subsoil possesses key advantages to help water operators. Aquifers offer a reservoir--where there is no room for surface storage--and uses the capacity for inter-seasonal and inter-year storage that natural systems provide [10; 11]. Systems like direct well injection or infiltration with either ponds, basins, or shallow buried trenches have been successfully implemented in small to large scale projects [12; 13; 14]. Furthermore, in coastal areas affected by saltwater intrusion, both systems may endure a particularly efficient way to tackle contamination because the water infiltration acts as a barrier to saline encroachment and, at the same time, allows the recovery of salinized aquifers [15]. Well injection offers advantages such as no evaporative losses, algae, or mosquitoes, and no loss of prime land. Alternatively, surface infiltration offers a potentially low-cost way to reclaim wastewater during the migration of recycled water through the vadose zone, which can result in improved water quality via biological, chemical, and physical processes before reaching the water table [16]. Schemes using the favorable characteristics of soil, subsoil, and aquifer for further (advanced) treatment of the infiltrated water are called SAT (Soil Aquifer Treatment) and usually have severe restrictions in terms of water quality used for the procedure [17].