Managed Aquifer Recharge Sites Research Articles

Identifying managed aquifer recharge and rain water harvesting sites and structures for storing non-conventional water using GIS-based multi-criteria decision analysis approach

In arid climates, conventional water resources are severely limited and stressed in the face of rapid population growth and future climate change. So, it is necessary to find alternative non-conventional water resources for use in drought situations. Additionally, the non-conventional water resources in these areas are not sufficient to meet future water demand. Therefore, non-conventional water resources can be adopted as a strategic reserve to bridge the gap between water supply and demand in case of emergency and drought events. These resources might include rainwater harvesting, treated wastewater, and desalinated seawater. Managed aquifer recharge (MAR) can be applied to store these resources in the hydrogeological system using Geo information System—Multi Criteria Decision Analysis (GIS-MCDA) approach for determining the suitable MAR location for storage. North-west Kingdom of Saudi Arabia area was chosen for this study because it is extremely arid, has high potential for social and economic development, and it has newly constructed non-conventional water infrastructures distributed throughout the area including water desalination plants, Tertiary Sewage Effluent (TSE) waste water plants, and flash-flood storage dams. To identify the suitable MAR site location and structure, different data related to aquifer hydrogeology, surface hydrology, hydrometeorology, and water quality were applied. Then, GIS-MCDA holistic approach was applied with aid of ordered weighting average (OWA) technique. Finally, two maps were created to show the MAR location and structure type. Potential map indicates that ~ 18.85% of the area is suitable for MAR installations. About 0.17% of the total area exhibited very high potential, where infiltration ponds can be applied, 1.86% had high potential for construction of check dams with diversion channels, and 16.82% had moderate potential for installation of recharge wells. Additionally, 56 MAR structures were proposed and a map showing their locations has been created. Thus, results indicated that the study area is promising for MAR installation. These maps could aid the decision makers to propose a sustainable development plan for the future water resources of the area.

Proposal for a managed aquifer recharge feasibility index for southern Portugal using multi-criteria decision analysis

Water scarcity in the Mediterranean region requires the adoption of new and optimized water resources management tools that allow a progressive climate change adaptation, being one of the main drivers for the employment of alternative water storage measures such as Managed Aquifer Recharge (MAR). To promote the implementation of these measures, this study evaluates the application of a MAR feasibility index mapping to southern Portugal, employing Multi-Criteria Decision Analysis (MCDA). A participatory approach – developed within the AGREEMAR project – aims for the characterization of the intrinsic site suitability, water availability and demand, where the stakeholder inputs are embedded in the weighting computation process.The results obtained demonstrate prevalent moderate MAR feasibility across the entire region (78% of the area) with an increased percentage of the area corresponding to high MAR feasibility (22%) strongly related to highly suitable geological features. A comparative analysis with the Analytical Hierarchical Process (AHP) showed minor high MAR feasibility areas (7%), and feasibility class transitions between the directly above or below classes.A sensitivity analysis, conducted based on a one-at-a-time (OAT) variation of the criteria weights, assessed the impact of the weighting methods on feasibility class changes. For the AGREEMAR method, changes in the weight of 10 of the 28 considered criteria resulted in negligible changes when compared to the original feasibility map, while for AHP 3 out of 28 produced minor changes. The remaining criteria showed important modifications in the feasibility maps, which underlined AGREEMAR method weights provided higher stability in the results.The study provides information about a MAR site selection process procedures, allowing replication. The dissemination of the results is expected to raise awareness of MAR among stakeholders and support scientifically-based water resources management decision-making.

An integrated groundwater vulnerability and artificial recharge site suitability assessment using GIS multi-criteria decision making approach in Kayseri region, Turkey

Groundwater resources worldwide face significant challenges that require urgent implementation of sustainable measures for effective long-term management. Managed aquifer recharge (MAR) is regarded as one of the most promising management technologies to address the degradation of groundwater resources. However, in urban aquifers, locating suitable areas that are least vulnerable to contamination for MAR implementation is complex and challenging. Hence, the present study proposes a framework encapsulating the combined assessment of groundwater vulnerability and MAR site suitability analysis to pinpoint the most featured areas for installing drywells in Kayseri, Turkey. To extrapolate the vulnerable zones, not only the original DRASTIC but also its multi-criteria decision-making (MCDA)–based modified variants were evaluated with regard to different hydrochemical parameters using the area under the receiver operating characteristic (ROC) curve (AUC). Besides, the fuzzy analytical hierarchy process (FAHP) rationale was adopted to signify the importance level of criteria and the robustness of the framework was highlighted with sensitivity analysis. In addition, the decision layers and the attained vulnerability layer were combined using the weighted overlay (WOA). The findings indicate that the DRASTIC-SWARA correlates well with the arsenic (AUC = 0.856) and chloride (AUC = 0.648) and was adopted as the vulnerability model. Groundwater quality parameters such as chloride and sodium adsorption ratio, as well as the vadose zone thickness, were found to be the most significant decision parameters with importance levels of 16.75%, 14.51%, and 15.73%, respectively. Overall, 28.24% of the study area was unsuitable for recharge activities with high to very high vulnerability, while the remaining part was further prioritized into low to high suitability classes for MAR application. The proposed framework offers valuable tool to decision-makers for the delineation of favorable MAR sites with minimized susceptibility to contamination.

Site-specific condition evaluation for managed aquifer recharge (MAR) site selection in granitic aquifers, Ghana

ABSTRACT Water has prominence over all the usable natural resources to humankind due to its very significance to human life. Approximately, 70% of Ghana's populace relies on groundwater exploitation for freshwater consumption. Managed aquifer recharge is capable of sustaining water resources for all livelihood activities. Underperformance of MAR systems is often due to site-specific hydrogeological conditions turning out to be less favorable than anticipated. This study evaluates the site-specific conditions for MAR sites identification in granitic aquifers, integrating in situ hydrogeological factors and GIS-MCDA. One hundred and twenty-one datasets from different boreholes comprising hydro geophysics, borehole drilling and pump test reports were used. The constraint mapping results indicate 92% suitable for MAR application within the study area, implying available enormous bare lands for flooding recharge technique. The suitability analysis discloses that 48 and 51% of the studied area fall within very high and high suitable zones, respectively, showing convincing and great potential to support infiltration ponds for MAR technology application. The valuable information provided through this study can serve as a guide for MAR implementation and for sustainable groundwater resources management within the Upper East region of Ghana.

Introducing a tailored site delineation approach to optimize the design of managed aquifer recharge surface spreading infrastructure

Managed aquifer recharge (MAR) is an emerging solution to effectively replenish overused groundwater resources, but high associated costs often hinder its uptake. There are several parameters to consider when determining the cost of MAR, including recharge types, scale of MAR schemes, land acquisition, operation and maintenance period, and the hydrogeological setting. Hydraulic conductivity and its spatial variability are the most significant hydrogeological parameters for predicting infiltration rates at MAR sites, but limited data availability makes accurate predictions often challenging. Hence, it is essential to increase data availability to optimize MAR efficiency and to better assess its economic performance. Therefore, a novel approach for MAR planning is presented in this article to efficiently enhance the data availability during the conceptual stage of MAR planning by combining site exploration, spatially resolved infiltration rate estimation, and cost analysis. The approach was applied at an actual MAR site in Vincenza, Italy, and incorporated an electromagnetic induction survey and direct push profiling as across-scale investigation methods to enhance site delineation and subsequent parameterization of the identified zones using laboratory analysis of collected samples. This MAR site is particularly suitable for its heterogeneous subsurface structure and potential to counteract groundwater depletion. The performed investigation resulted in an image of the lateral variation of subsurface conditions and allowed the delineation of three zones with different infiltration behavior, with 99.5% of infiltration occurring in just two zones, representing only 22.1% of the site. In this particular scenario, the overall cost per cubic meter of recharged water can be reduced by 59.1% by identifying and eliminating unfavorable zones. This study provides scientists and practitioners with a useful tool for MAR planning that can be applied to a wide range of sites with complex geology, thereby reducing water costs, minimizing the environmental impact of infrastructure construction, and reducing land use conflicts.

Managed aquifer recharge site suitability analysis in the Nabogo Basin of Ghana using GIS and Monte Carlo simulation-aided analytic hierarchy process

Managed aquifer recharge site suitability analysis in the Nabogo Basin of Ghana using GIS and Monte Carlo simulation-aided analytic hierarchy process

The main impacts of a managed aquifer recharge using AHP-weighted overlay analysis based on GIS in the eastern Wasit province, Iraq

Abstract The management of groundwater recharge success and sustainability depends on many site characteristics. It is essential to integrate the maps of site’s suitability and characteristics to identify suitable areas. The purpose of this study is to use a geographic information system (GIS) to find potential places for a project using managed aquifer recharge (MAR) in the eastern Wasit province, Iraq. Data for four effective criteria, terrain slope, Soil type/texture, drainage density, and hydrogeological efficiency, were collected, and a categorization map for each GIS criterion was subsequently created. The four steps are performed to identify this site: defining the problem, screening for the suitable areas, after the suitability map, and after the screening; the suitability mapping is divided into two zones: suitable zone and unsuitable zone. The results indicate that the site suitability for conducting aquifer recharge was classified into five categories, i.e., very high, high, moderate, low, and very low potentiality. These areas cover 26.83, 34.71, 24.98, 11.56, and 1.79%, respectively. GIS is widely acknowledged as an efficient approach for choosing MAR sites. This approach gives a better reference for analyzing suitable sites and the potential implications of applying MAR in an aquifer in similar water-stressed areas.

Retraction: Delineation of potential managed aquifer recharge sites of Kuchlak sub-basin, Balochistan, using remote sensing and GIS

Retraction: Delineation of potential managed aquifer recharge sites of Kuchlak sub-basin, Balochistan, using remote sensing and GIS

An extended colloid filtration theory for modeling Escherichia coli transport in 3-D fracture networks

Microbial transport in fractured carbonate rock using enhanced solutions is a significant and neglected research topic in the literature. We propose an extended colloid filtration theory (CFT) combined with a particle-tracking following streamlines (PTFS) model for the rapid prediction of breakthrough curves (BTCs) and plumes of pathogens in three-dimensional (3-D) discrete fracture networks (DFNs). We adapted CFT in porous media to pathogen transport in fractures containing Terra Rossa (soil) deposits. As an example of the model capability, a simulation was used to predict the 3-D motion field and Escherichia coli count in groundwater originating from the Forcatella managed aquifer recharge (MAR) Facility (Brindisi, Italy) using a DFN composed of 3,900 fractures. In arid regions, MAR facilities are significant for sustaining basic human needs, such as freshwater supply for drinking and crop production. The Markov chain Monte Carlo (MCMC) technique was applied to E. coli counts in the collected water samples to increase data representativeness. The pathogen transport coefficients were further supported by batch filtration tests carried out in the CNR/IRSA Laboratory (Bari, Italy). The mean E. coli attachment rate coefficient of 0.15 × 10−8 m2 d–1 (sticking efficiency = 1.1 × 10−8 m) resulted in a 2.1 log10 removal in 600 m of reclaimed water filtration. The simulation output visualized the E. coli 3-D pathways in groundwater and the positions of contaminated groundwater spring outflows on Forcatella Beach. The simulation results agreed with the mean MCMC output of E. coli concentrations in bathing water under unperturbed geochemical and environmental flow and transport conditions. However, results indicate that concentrations of pathogenic strains, parasites, and enteric viruses may enter the marine environment of MAR sites during flood periods.

Application of physical clogging models to Managed Aquifer Recharge: a review of modelling approaches from engineering fields

Managed Aquifer Recharge (MAR) sites suffer from the long-lasting problem of clogging. The causes of clogging are physical, biological, chemical and mechanical processes and their complex interaction, with physical clogging being recognised as the predominant process. The intrusion and deposition of particles during water recharge affect the hydraulic properties of the infiltration surface, resulting in a decline in the infiltration capacity of the site over the operating years. Cleaning operations are necessary to restore the original infiltration rates. For this purpose, assessing the risk of clogging can determine the site’s vulnerability and improve the scheme’s design. Numerical models are essential to replicate physical clogging processes and predict the decline in infiltration rates. So far, predictive tools for physical clogging assessment have been missing in MAR literature. Hence, the purpose of this study is to analyse and reorganise physical clogging models from applied engineering fields dealing with water infiltration in natural heterogeneous systems. The modelling approaches are illustrated, starting from the main assumptions and conceptualisation of the soil volume and intruding particles. The individual processes are untangled from the multiple studies and reorganised in a systematic comparison of mathematical equations relevant to MAR applications. The numerical models’ predictive power is evaluated for transferability, following limitations and recommendations for a process-based model applicable to surface spreading schemes. Finally, perspectives are given for clogging risk assessment at MAR sites from modelling and site characterisation. The predictive tool could assist decision-makers in planning the MAR site by implementing cost-effective strategies to lower the risk of physical clogging.

Identifying the suitable managed aquifer recharge (MAR) strategy in an overexploited and contaminated river basin.

Managed aquifer recharge (MAR) is a promising adaptation measure to reduce vulnerability to climate change and hydrological variability. However, in areas where the basin is highly polluted, densely populated, and intensely cultivated, implementing suitable MAR strategies is a significant challenge. This study used a geographic information system-based multicriteria decision analysis (GIS-MCDA) approach to delineate the MAR potential sites using seven thematic layers describing surface and subsurface features. Further, basin-specific MAR approach was developed using information such as polluted water areas, canal network distribution for water supply, and cropping patterns. The results of this study indicate that only 17% of the area is highly suitable, while 54% and 29% were found moderately suitable and unsuitable for the MAR approach. Since most highly and moderately suitable sites were falling in the agricultural areas, agricultural-based MAR (AgMAR) was considered a preferred option. AquaCrop model for sugarcane was developed considering excess canal water supply during the grand growth stage to understand the AgMAR potential in the study area. It was observed that the potential recharge under normal irrigation scenarios varies from 135.5 to 272mm/year, which can be increased through AgMAR up to 545mm/year depending on the water availability for excess irrigations. This study provides an improved understanding of the parameters that should be considered for MAR site selection and post-GIS-MCDA analysis to assess the basin-specific MAR strategy.

Understanding and predicting physical clogging at managed aquifer recharge systems: A field-based modeling approach

Managed aquifer recharge (MAR) techniques are in demand to cope with water scarcity challenges posed by climate change and groundwater overexploitation. One of the long-lasting technical issues associated with MAR systems is physical clogging. The intrusion and deposition of external fines during water recharge reduce the infiltration capacity of the site over time. Operation and maintenance (O&M) costs are experienced directly at the site to restore the original efficiency of infiltration rates. Thus, investors need reliable estimations of the risk of clogging during the planning of the site. As a rule, in MAR design, the main parameter of concern for physical clogging is the total suspended solids (TSS), and most clogging models rely on experiment calibrations in 1D sand columns. However, secondary processes can control the development and spatial distribution of physical clogging in field conditions. The proposed work aims to detect key clogging factors directly in the field and to model these processes for reproducibility at other sites. The fieldwork is conducted at the two-stage infiltration basin in Suvereto (Tuscany, Italy). Spatial factors are included in the analysis (i.e. basin topography) to explain clogging patterns in the field altered by erosion processes. The observed clogging profiles at two sampled locations exhibiting clogging are replicated by a mathematical model. Based on the computation of annual erosion rates in the pond and fines’ redistribution, the exceeding fines’ contents over depth are validated with an RMSE of 2.53% and 12.53%. The infiltration capacity of the site is estimated to reach a stable value of 90% of the initial infiltration capacity over 20 years, given the Suvereto basin features. The model's parameterisation from field measurements represents a great advantage over existing clogging models due to its transferability to other MAR sites. The assessment of the risk of clogging supported by field characterization and numerical modelling is cost-effective and assists the deduction of O&M schemes for MAR sites.

Risk assessment for the prevention of managed aquifer recharge (MAR) facility failure during the operation and the expansion phases

This comprehensive risk assessment, done for a MAR facility in Tarnów, southern Poland, covers two MAR techniques: infiltration ditches and induced bank filtration during the operation and planned potential expansion phases. Two methods were applied: the semi-quantitative risk assessment matrix and the probabilistic risk assessment – fault tree analysis (PRA-FTA), and their advantages and limitations analysed. Both methods examine a range of technical and non-technical risks that may pose a threat to the efficient functioning of the MAR facility in Tarnów, which supplies about 25% of the city’s population with drinking water. It was found that 34 of the 65 risks analysed could pose a low to high risk for the Świerczków well field. The predominant risks potentially reducing MAR efficiency or leading to MAR failure are technical ones. According to the PRA-FTA method, if no preventive measures are taken, there is a 99.5 and 99.3% probability of the MAR system failing during the operational and expansion phases, respectively. The results indicate that the most serious risk is associated with the insufficient initial removal from the recharge river water of suspended solids, which clog infiltration ditches. The risks scored as medium relate to the threat of groundwater inflow from an extensive industrial zone, lying to the east of the well field, and to climate change negatively affecting the quantity of groundwater resources. This is the first example in Poland of a risk assessment for an existing MAR facility and its expansion, based on a broad spectrum of technical and non-technical risks present at the Świerczków well field, using two methods: the risk assessment matrix and PRA-FTA. This case study is a practical example of how to perform a risk analysis for a MAR site. It can make an important contribution to existing knowledge in this field and enrich the subject literature, a particularly relevant aspect given the widespread use of MAR techniques in Central Europe for the supply of drinking water to the public.

Sensitivity Analysis for Multi-Criteria Decision Analysis Framework for Site Selection of Aquifer Recharge with Reclaimed Water

The pressure on Egypt’s limited water resources has increased as a result of the country’s growing industrial and agricultural sectors, coupled with climate change impacts and population growth. To overcome the current water stress situation, the utilization of new technologies such as managed aquifer recharge (MAR) is thought to be key for expanding the use of non-conventional water resources and providing necessary water supplies. Managed aquifer recharge can boost groundwater recharge and promote greater water accessibility. Suitability maps for MAR are widely offered as a tool to aid in decision-making in the context of balancing water demand and supply. Conducting a sensitivity analysis to validate suitability mapping can enhance the understanding of the results and pinpoint the influencing factors. The West Delta region was chosen as a case study given the existence of two MAR sites to examine the suitability of implementing MAR projects with reclaimed water. In this work, a spatially explicit sensitivity analysis is performed on a newly developed framework for MAR suitability maps that use multi-criteria decision analysis (MCDA) to determine suitable locations for MAR implementation, using spreading methods techniques. The performed sensitivity analysis uses spatial visualization to examine the effect of various weighted criteria on the final outputs and identifies criteria that are especially sensitive to weight changes. The results of the sensitivity analysis indicate that the applied MCDA framework for the suitability mapping in West Delta produced robust results in terms of the most suitable sites for MAR. The obtained results also indicate the possibility of the use of the suggested framework for arid environments with comparable data availability. Moreover, the results emphasize the possible use of suitability maps in sustainable groundwater management plans to support the actual implementation of MAR projects in the West Delta.

Controls on flood managed aquifer recharge through a heterogeneous vadose zone: hydrologic modeling at a site characterized with surface geophysics

Abstract. In water-stressed regions of the world, managed aquifer recharge (MAR), the process of intentionally recharging depleted aquifers, is an essential tool for combating groundwater depletion. Many groundwater-dependent regions, including the Central Valley in California, USA, are underlain by thick unsaturated zones (ca. 10 to 40 m thick), nested within complex valley-fill deposits that can hinder or facilitate recharge. Within the saturated zone, interconnected deposits of coarse-grained material (sands and gravel) can act as preferential recharge pathways, while fine-textured facies (silts and clays) accommodate the majority of the long-term increase in aquifer storage. However, this relationship is more complex within the vadose zone. Coarse facies can act as capillary barriers that restrict flow, and contrasts in matric potential can draw water from coarse-grained flow paths into fine-grained, low-permeability zones. To determine the impact of unsaturated-zone stratigraphic heterogeneity on MAR effectiveness, we simulate recharge at a Central Valley almond orchard surveyed with a towed transient electromagnetic system. First, we identified three outcomes of interest for MAR sites: infiltration rate at the surface, residence time of water in the root zone and saturated-zone recharge efficiency, which is defined as the increase in saturated-zone storage induced by MAR. Next, we developed a geostatistical approach for parameterizing a 3D variably saturated groundwater flow model using geophysical data. We use the resulting workflow to evaluate the three outcomes of interest and perform Monte Carlo simulations to quantify their uncertainty as a function of model input parameters and spatial uncertainty. Model results show that coarse-grained facies accommodate rapid infiltration rates and that contiguous blocks of fine-grained sediments within the root zone are >20 % likely to remain saturated longer than almond trees can tolerate. Simulations also reveal that capillary-driven flow draws recharge water into unsaturated, fine-grained sediments, limiting saturated-zone recharge efficiency. Two years after inundation, fine-grained facies within the vadose zone retain an average of 37 % of recharge water across all simulations, where it is inaccessible to either plants or pumping wells. Global sensitivity analyses demonstrate that each outcome of interest is most sensitive to parameters that describe the fine facies, implying that future work to reduce MAR uncertainty should focus on characterizing fine-grained sediments.

Improving clogging predictions at managed aquifer recharge sites: a quantitative assessment on the vertical distribution of intrusive fines

Managed aquifer recharge (MAR) is an emerging approach to enhancing water storage capacity, improving water supply security and countering groundwater overexploitation. However, physical clogging, i.e. accumulation of suspended organic and inorganic solids within a sediment matrix, can lead to a significant reduction of infiltration rates and present difficulties in the functioning of MAR infrastructure. Clogging and subsequent reduction in infiltration capacity are often quantified based on monitoring data or field investigations, rather than on forecasts. Existing predictive models require specific parameterisation, making an application to heterogeneous sites, or under changing conditions, difficult. Hence, a generalised understanding of how intrusive fine particles distribute over depth during water recharge cycles for typical MAR infiltration basin sediments is needed to predict clogging susceptibility and clogging patterns already in the planning phase and before operation of MAR schemes. The study will contribute to operational reliability, deduce optimised management practices, and, ideally, reduce maintenance efforts. To achieve this goal, data from different soil-column clogging experiments are reviewed and complemented with experiments to establish a generally valid relationship for the vertical distribution of intrusive fines under consideration of the primary porous media’s and intruding particles’ characteristics. Obtained results allow for quantification of the amount of particles retained at the surface of the porous media, i.e. formation of a filter cake, a description of the distribution of fines over depth, and total clogging depth. Finally, the findings are applied to a real MAR case study site to showcase the quantification of clogging effects on recharge rates.

RETRACTED: Delineation of potential managed aquifer recharge sites of Kuchlak sub-basin, Balochistan, using remote sensing and GIS

In the Kuchlak Sub-Basin (Pakistan), groundwater is overexploited, resulting in growing stress on groundwater resources. The water table level has declined rapidly due to intensive pumping. Artificial recharge methods and good management strategies are vital for the sustainable production of groundwater resources. Managed aquifer recharge is an artificial way of recharging the subsurface aquifers using surplus surface water, treated wastewater, and stormwater. It is a potential strategy for increasing freshwater supply and adapting to climate change. The present study proposes a method to delineate potential zones for MAR suitability in the Kuchlak Sub-Basin. INOWAS, a web-based tool, is utilized for narrowing down the available MAR techniques based on the hydrogeologic parameter and objectives of the study area. A geographic information system (GIS) coupled with the multi-criteria decision analysis (MCDA), commonly known as GIS-MCDA, is used to develop the MAR suitability map. Six criterion maps, including geology, land use, slope analysis, drainage density, soil, and rainfall, were created in ArcGIS for suitability mapping. The criterion maps are ranked and weighted based on their relative contribution to the groundwater recharge and published literature using the Multi Influence Factor (MIF) method. The final suitability map was developed by overlaying all the criterion maps using a weighted linear combination (WLC) technique. The MAR suitability map was divided into five zones, namely, very high, high, moderate, very low, and low. The unsuitable zones reflect the urban and slope constraints that reduce surface infiltration. The suitability map reveals that 45% of the Kuchlak Sub-Basin exists in a very high-high suitability zone, 33% in moderate, and 17% in a very low-low suitability zone, while 5% of the study area was unsuitable due to the urban and slope constraints. The MAR suitability map developed in this study can serve as a basis for conducting a focused analysis of MAR implementation. Furthermore, the technique and results of this study may aid in mapping MAR suitability in any arid or semi-arid region.

Soil characteristics and redox properties of infiltrating water are determinants of microbial communities at managed aquifer recharge sites.

In this study, we conducted a meta-analysis of soil microbial communities at three, pilot-scale field sites simulating shallow infiltration for managed aquifer recharge (MAR). We evaluated shifts in microbial communities after infiltration across site location, through different soils, with and without carbon-rich amendments added to test plots. Our meta-analysis aims to enable more effective MAR basin design by identifying potentially important interactions between soil physical-geochemical parameters and microbial communities across several geographically separate MAR basins. We hypothesized infiltration and carbon amendments would lead to common changes in subsurface microbial communities at multiple field sites but instead found distinct differences. Sites with coarser (mainly sandy) soil had large changes in diversity and taxa abundance, while sites with finer soils had fewer significant changes in genera, despite having the greatest increase in nitrogen cycling. Below test plots amended with a carbon-rich permeable reactive barrier, we observed more nitrate removal and a decrease in genera capable of nitrification. Multivariate statistics determined that the soil texture (a proxy for numerous soil characteristics) was the main determinant of whether the microbial community composition changed because of infiltration. These results suggest that microbial communities in sandy soil with carbon-rich amendments are most impacted by infiltration. Soil composition is a critical parameter that links between microbial communities and nutrient cycling during infiltration and could influence the citing and operation of MAR to benefit water quality and supply.

Monitored and Intentional Recharge (MIR): A Model for Managed Aquifer Recharge (MAR) Guideline and Regulation Formulation

Guidelines and regulatory frameworks for conducting managed aquifer recharge (MAR) are scarce worldwide compared to the countries where MAR projects operate. At the same time, guidelines and regulations are crucial to implementing MAR activities safely, respecting human health and the environment, and guaranteeing the sustainability of the intentional recharge. The present study aims to provide a conceptual model comprising the minimum elements to consider when drafting guiding and normative MAR documents. To this end, aspects discussed in nine guidelines were evaluated through a score that allowed their significance to be assessed. The authors also reviewed 22 regulations, guidelines, or MAR site operation rules to construct the monitored and intentional recharge (MIR) conceptual model. This effort was enhanced by active participation in the real drafting of two national regulating documents for MAR. The evaluation of aspects in the documents showed the importance of water reuse and risk and impact assessment. The MIR conceptual model comprises nine blocks that summarize the most important aspects to consider. This conceptual model, which guides MAR regulations in two countries, has great potential for application in different sites under diverse contexts.

Managed aquifer recharge in karstic systems:Site suitability mapping by coupling multi-criteria decision analysis with remote sensing and hydrologic modeling

Managed aquifer recharge (MAR) offers a promising strategic management alternative for water storage and subsequent recovery to alleviate water shortage and to protect coastal aquifers from saltwater intrusion. Selecting potentially suitable recharge sites remains challenging, particularly in heterogeneous karst systems. In this study, MAR site suitability in a karst coastal aquifer is examined using a new geospatial approach that accounts for aquifer rechargeability properties, water availability, and economic-environmental attractiveness. For this purpose, multi-criteria decision analysis (MCDA), supported by pairwise comparisons, with an intrinsic karst aquifer rechargeability index is coupled with a raster-based hydrologic model that was forced by remotely-sensed precipitation, temperature, and land use data. The approach was successfully used to define exclusionary zones and to identify sites with high MAR potential that were independently collocated with hydrogeological indicators ascertaining its potential for site suitability mapping in systems with prevailing karstic aquifers.