ABSTRACT
Objective: The objective of this study is to investigate the existing literature on the development and application of the FREEWAT platform as a tool for groundwater modeling, addressing the technical implications and limitations that the technical-scientific community has studied so far.
Method: The methodology adopted for this review comprises the application of the PRISMA method. The search term "FREEWAT" was used in the Web of Science and Scopus databases. Based on the studies found, the PRISMA method divides the systematic review process into four stages: identification, selection, eligibility, and inclusion. The articles that met the eligibility criteria were subjected to bibliometric analysis using the CiteSpace software, enabling the visualization of new trends and existing gaps in the scientific literature on the topic.
Results and Discussion: A total of 22 articles were analyzed, highlighting studies on the application of FREEWAT in coastal aquifers, along with the addition of different tools to the platform. The results indicate that FREEWAT is still underutilized, especially outside Europe. However, its application is highly viable. Future research should aim to deepen its capacity for representing complex systems, as well as improving the quality and quantity of input data used to ensure greater reliability of the results obtained.
Research Implications: The use of the FREEWAT platform is an attractive option for applications in both simple and complex systems. lts integration with QGIS software and the availability of multiple simulation modules facilitate the development of a complex and robust database for groundwater modeling.
Originality/Value: FREEWAT is a free and open-source platform that stands out due to its integration of numerical simulation models for groundwater systems, such as MODFLOW, with the QGIS software environment. This integration is valuable for supporting planning, management, and monitoring activities of these systems. Therefore, this study contributes to the existing literature by conducting a comprehensive review of FREEWAT's use, providing valuable insights into its application in systems with different characteristics, and identifying key trends, influential studies, and emerging research areas.
Keywords: Systematic Literature Review, Climate Change, Groundwater Flow Model.
RESUMO
Objetivo: O objetivo deste estudo é investigar a literatura existente sobre o desenvolvimento e aplicação da plataforma FREEWAT como ferramenta para modelagem de aguas subterráneas, abordando as implicações técnicas e limitações que a comunidade técnico-científica tem estudado até agora.
Método: A metodologia adotada para esta revisão compreende a aplicação do método PRISMA. Utilizou-se о termo de busca "FREEWAT" nas bases de dados Web of Science e Scopus. A partir dos estudos encontrados, o método PRISMA divide a elaboração da revisão sistemática em quatro etapas: identificação, seleção, elegibilidade e inclusáo. Os artigos que atenderam aos critérios de elegibilidade foram subtidos a análise bibliométrica através do software CiteSpace, possibilidando a visualização de novas tendências e as lacunas existentes na literatura cientifica sobre a temática.
Resultados e Discussão: Um total de 22 artigos foram analisados, destacando-se artigos de aplicação do FREEWAT em aquíferos costeiros, juntamente com a adicäo de diferentes ferramentas a plataforma. Os resultados indicam que о FREEWAT ainda é pouco utilizado, especialmente fora da Europa. No entanto, sua aplicação é altamente viável. Novas pesquisas devem buscar aprofundar sua capacidade de representação de sistemas complexos, bem como aumentar a qualidade e quantidade dos dados de entrada utilizados, para garantir maior confiabilidade aos resultados obtidos.
Implicações da Pesquisa: A utilização da plataforma FREEWAT é uma opção atraente para aplicações tanto em sistemas simples, quanto em sistemas complexos. Sua integração com o software QGIS e a existência de diversos módulos de simulação facilitam a elaboração de um banco de dados complexo e robusto para modelagem de aguas subterráneas.
Originalidade/Valor: O FREEWAT é uma plataforma gratuita e de código aberta, que se destaca devido a integração de modelos numéricos de simulação em sistemas de aguas subterráneas, como о MODFLOW, com o ambiente do software QGIS. Essa integração mostra-se valiosa para dar suporte a atividades de planejamento, gestão e monitoramento dos sistemas. Portanto, este estudo contribui para a literatura existente ao realizar uma revisão abrangente sobre a utilização do FREEWAT. Fornecendo insights valiosos sobre sua aplicação em sistemas de diferentes característixas, e identificando tendéncias-chave, estudos influentes e áreas de pesquisa emergentes.
Palavras-chave: Revisão Sistemática da Literatura, Mudanças Climáticas, Modelo de Fluxo Subterráneo.
RESUMEN
Objetivo: El objetivo de este estudio es investigar la literatura existente sobre el desarrollo y aplicación de la plataforma FREEWAT como herramienta para la modelización de aguas subterráneas, abordando las implicaciones técnicas y limitaciones que la comunidad técnico-científica ha estudiado hasta ahora.
Método: La metodología adoptada para esta revisión comprende la aplicación del método PRISMA. Se utilizó el término de búsqueda "FREEWAT" en las bases de datos Web of Science y Scopus. A partir de los estudios encontrados, el método PRISMA divide la elaboración de la revisión sistemática en cuatro etapas: identificación, selección, elegibilidad e inclusión. Los artículos que cumplieron con los criterios de elegibilidad fueron sometidos a un análisis bibliométrico a través del software CiteSpace, permitiendo la visualización de nuevas tendencias y las brechas existentes en la literatura científica sobre la temática.
Resultados y Discusión: Se analizaron un total de 22 artículos, destacándose aquellos sobre la aplicación de FREEWAT en acuíferos costeros, junto con la adición de diferentes herramientas a la plataforma. Los resultados indican que FREEWAT aún es poco utilizado, especialmente fuera de Europa. Sin embargo, su aplicación es altamente viable. Las nuevas investigaciones deberían profundizar en su capacidad para representar sistemas complejos, así como en la mejora de la calidad y cantidad de los datos de entrada utilizados, para garantizar una mayor confiabilidad en los resultados obtenidos.
Implicaciones de la investigación: El uso de la plataforma FREEWAT es una opción atractiva para aplicaciones tanto en sistemas simples como en sistemas complejos. Su integración con el software QGIS y la existencia de múltiples módulos de simulación facilitan la creación de una base de datos compleja y robusta para la modelización de aguas subterráneas.
Originalidad/Valor: FREEWAT es una plataforma gratuita y de código abierto que destaca por la integración de modelos numéricos de simulación en sistemas de aguas subterráneas, como MODFLOW, con el entorno del software QGIS. Esta integración es valiosa para apoyar actividades de planificación, gestión y monitoreo de estos sistemas. Por lo tanto, este estudio contribuye a la literatura existente al realizar una revisión exhaustiva sobre el uso de FREEWAT, proporcionando información valiosa sobre su aplicación en sistemas con diferentes características e identificando tendencias clave, estudios influyentes y áreas de investigación emergentes.
Palabras clave: Revisión Sistemática de la Literatura; Cambio Climático; Modelo de Flujo Subterráneo.
1 INTRODUCTION
The impacts of climate change and human interference are felt in all components of the hydrological cycle. Linked to the scenario of increasing demand for water, the potential for using groundwater to adapt to climate change reinforces the need for efficient management to ensure long-term water supply (Mays, 2013; UNESCO, 2022).
Groundwater flow models are excellent tools to support efficient and sustainable aquifer management. According to Anderson et al. (2015), a good groundwater model is one that best quantitatively represents the hydraulic head in space and time in a simplified representation of the complex conditions in the aquifer. Numerical models have shown good results in representing this complexity, as well as being excellent aids in better interpreting the processes that occur in the aquifer (Nogueira & Kiang, 2015).
MODFLOW 1$ the most widely used groundwater flow model in the world. Its popularity, coupled with its modular structure and detailed documentation, has allowed it to be coupled with several other physical process models and software, such as watershed models such as PRMS (Markstrom et al., 2008)and SWAT (Kim et al., 2008), and hydrodynamic models such as HEC-RAS (Rodriguez et al., 2008)and SWIFT2D (Wang et al., 2007), among others.
Between 2015 and 2017, the European Union funded the FREEWAT project. In this project, several European researchers developed FREEWAT, a free and open-source platform that includes tools for water resources management in the QGIS software environment (Rossetto et al., 2018). The integration of numerical models with Geographic Information Systems (GIS) is valuable to support groundwater planning, management and monitoring activities, allowing a detailed representation of the related systems and processes, both temporally and spatially, providing a complete characterization of the flow parcels involved (Anderson et al., 2015; Ferré, 2017).
FREEWAT includes modules for water resources management and planning; solute transport in the unsaturated zone; crop growth and agricultural water demands; groundwater quality; calibration, uncertainty and sensitivity analysis; and hydrogeological data analysis, interpretation and visualization (Rossetto ef al., 2015). The existence of different modules allows FREEWAT to be applied in different areas and under different conditions, highlighting its versatility and adaptability to different contexts and needs.
This study aims to analyze the application of FREEWAT for the representation of aquifer systems and simulation of groundwater flow. The work consists of a literature review in which we sought to synthesize knowledge in the area through the identification, selection and critical evaluation of several scientific studies. Thus, the objective is to deepen knowledge about the platform, indicating trends and gaps that need to be filled in new studies.
2 METHODOLOGY
A systematic review is conducted on a clearly formulated question (Moher et al., 2009). The methodology used in this review adopts the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) method. PRISMA divides systematic reviews into four stages: identification, selection, eligibility and inclusion (Figure 1).
In the first stage, the bibliographic survey was carried out using the keyword "FREEWAT" in the Scopus and Web of Science (WoS) databases. Only articles written in English were considered. The search resulted in 27 articles found in Scopus and 16 articles found in WoS, totaling 43 articles. In the next stage, duplicate articles were eliminated from one of the databases, resulting in the final selection of 30 publications.
In the third stage, the articles were analyzed according to their relevance and adherence to the proposed theme, separating them into two distinct categories: (i) platform development and updates and (ii) applications in groundwater modeling. Titles, abstracts and keywords were analyzed and, at the end of this stage, 22 articles met the eligibility criteria. These articles were submitted to bibliometric analysis using the CiteSpace software, which is a tool that allows the visualization of new trends in the scientific literature by the frequency of citations and the centrality parameter, which is used to find and measure intellectual inflection points.
3 RESULTS AND DISCUSSIONS
3.1 STATE OF THE ART
3.1.1 Platform development and updates
Rossetto et al. (2015)present the FREEWAT project, funded by the European Union under the HORIZON 2020 program. The project's main objective is to develop an open-source, public domain platform, integrated with Geographic Information Systems (GIS), for simulating the quantity and quality of surface and groundwater, promoting the sustainable management of water resources. One of the main innovations cited by the authors is the project's participatory approach, with the inclusion of stakeholders not only in the discussion of the results, but also in the implementation of the model and in the construction of scenarios.
Cannata et al. (2016)addressed the integration of the MODFLOW Lak7 module into the FREEWAT environment to improve the simulation of surface-groundwater interactions, allowing for more effective consideration of surface water bodies in water resource management. The Lak7 module simulates the hydraulic interaction between lakes and groundwater by treating lake cells as inactive in the groundwater flow equation, providing detailed water balance summaries for each lake, including level, volume, fluxes, and errors, Which are printed in the MODFLOW output file.
De Filippis et al. (2017)showed the main tools included in the FREEWAT platform. In pre-processing, the AkvaGIS codes are available for analysis and interpretation of hydrochemical and hydrogeological data, and the Observation Analyses Tool (OAT), which facilitates the import, analysis and visualization of time series of data. For modeling, FREEWAT relies on MODFLOW-2005, which simulates groundwater flow, MT3DMS, which simulates solute transport in aquifers, SEAWAT, which models viscosity and densitydependent flows, and MODFLOW-OWHM, which integrates Farm Process to simulate water demand and supply in consumption units. Finally, post-processing can be performed using the UCODE 2014 code, which performs sensitivity analysis and parameter estimation to improve model fit.
Cannata & Neumann (2017)have deepened their knowledge about the OAT module in the FREEWAT plugin for QGIS. Designed to integrate environmental monitoring data into GIS applications, OAT allows for efficient pre-processing and post-processing of temporal data. OAT functionalities include: importing data from multiple sources; storing and managing time series in the QGIS environment, with associated metadata; filtering, aggregating and resampling of time series to fit the temporal discretization of the model; calculating derived variables, such as evaporation; comparing observed and simulated time series for model calibration and validation; and visualizing results, such as groundwater levels and water balance components.
Rossetto ег al. (2018)present the FREEWAT platform as an innovative and accessible platform for water resources management, with the potential to be widely adopted in different geographic and institutional contexts. The platform, with a specific focus on groundwater, combines geoprocessing and post-processing tools for spatial data with process-based simulation models, with the execution of distributed modeling codes. The platform is built as a plugin for the QGIS software, using the SpatialLite spatial database management system, integrating several simulation codes such as MODFLOW, MT3DMS, SEAWAT and UCODE 2014, for modeling groundwater flow, contaminant transport and model calibration.
Criollo et al. (2019)present the integration of FREEWAT with AkvaGIS. An easy-touse, open-source tool that allows the management, visualization and analysis of hydrochemical and hydrogeological data, as well as the preparation of input files for numerical groundwater flow models. AkvaGIS 1s divided into three main sections: data management, hydrochemical tools and hydrogeological tools. As with most modeling tools, the quality of the results generated with AkvaGIS depends on the quality and quantity of the data available.
The study Rossetto et al. (2019)sought to provide a robust solution for the joint management of surface and groundwater, especially in agricultural contexts, through the integration of the Farm Process (FMP) with a Crop Growth Module (CGM) in the FREEWAT platform. The FMP simulates water use, allowing the simulation of the water balance in units of water demand that can represent agricultural, urban or natural vegetation areas. The CGM, based on the EPIC model, simulates crop growth and estimates productivity based on water availability.
Bittner et al. (2020)integrated the LUKARS model, developed to simulate the discharge of springs in karst systems and assess the impacts of land use changes, into FREEWAT. The integration represents a valuable contribution to water resource management in karst systems, since FREEWAT offers an intuitive graphical interface and analysis tools that facilitate the application of the model by managers and researchers in the field. In addition, it allows the simulation of land use change scenarios that can provide important information for the sustainable management of groundwater resources in karst systems. Despite some limitations, such as the need for manual calibration, the study paves the way for future improvements and applications in different hydrological contexts.
3.1.2 Applications in groundwater modeling
Arce et al. (2023)uses numerical modeling through FREEWAT to quantify groundwater flows in adjacent basins in the Gallocanta Lake basin region, Spain. The model was calibrated with groundwater level monitoring data and validated against base flows from rivers and springs, in addition to including simulations of pumping ban and recharge reduction scenarios in the region. The results showed that the Gallocanta basin is hydrogeologically connected with the adjacent Piedra-Ortiz and Jiloca basins, with annual discharges of approximately 4Mm? and 1Mn°, respectively. The scarcity of hydrogeological data in the region may affect the accuracy of the model, since the calibration was based on a relatively small number of observation points. However, the results contribute significantly to the understanding of groundwater flow in the area.
In their work, Cannata et al. (2018)they applied FREEWAT to Lake Lugano, located on the border between Switzerland and Italy, to understand the interaction between the lake and the surrounding aquifers. The study was conducted with a participatory approach involving public administration, engineering companies and local environmental agencies, to ensure acceptance and reliability of the results. This was especially true due to the lack of detailed hydrogeological data, which is a common problem in this type of study. The results showed that most of the water flow occurs from the aquifers to the lake, with little interaction in the opposite direction. Overall, the participatory approach and the integration of modeling tools in a GIS environment make FREEWAT a promising platform for sustainable management of groundwater resources.
Chrysanthopoulos ef al. (2024)presented a detailed study on groundwater modeling in coastal aquifers in the Argolis Plain, Greece. The main objective was to investigate the performance of a groundwater model calibrated under pre-development conditions, under transient conditions, to assess the sustainability of water use in this aquifer. Despite using an extensive database, the existence of sparse or incomplete measurements was one of the challenges for the accuracy of the result. The initial run of the model in the steady state presented a Nash-Sutcliffe (NS) index of 0.54, considered moderate. After calibration, the NS increased to 0.99, showing an excellent correlation between simulated and observed values. In the transient state simulation, the model presented an NS of 0.90, indicating good performance even without recalibration. This result shows that steady-state calibration can provide accurate hydraulic parameters for transient state simulations, simplifying the modeling process and reducing the need for recalibration.
The article De Filippis et al. (2020)discusses the application of FREEWAT in thirteen case studies in different countries. The cases were grouped into five main themes. In the theme Coastal Aquifer Management, three areas were analyzed, the Island of Gozo in Malta, the Follonica-Scarlino Plain in Italy, and the Lavrion area in Greece, where the platform assessed the impacts of climate change, saline intrusion and aquifer recharge strategies. Studies in Slovenia, the Czech Republic and Turkey, within the theme Surface-Groundwater Integration, focused on optimizing the joint use of surface and groundwater, especially in agricultural areas. Recharge reduction and sea level rise were evaluated in cases in Germany and Romania, under the theme Climate Change Impacts. The theme Management of Transboundary Aquifers highlighted the importance of international cooperation for the sustainable management of shared aquifers, with studies in the Lake Lugano basin, shared by Switzerland and Italy, and in the Stampriet Transboundary Aquifer System, located between Namibia, Botswana and South Africa. Finally, the issues of irrigation, drainage and protection of wetlands were addressed with case studies in Ukraine, Italy and Estonia, under the theme Water Management in Rural Areas and Protection of Groundwater-Dependent Ecosystems. FREEWAT achieved consistent results, proving to be effective in different contexts, from the local to the river basin scale, and in different hydrogeological conditions.
Dadaser-Celik & Celik (2017)conducted a study on the interactions between surface water and groundwater in the Palas Basin, located in Turkey, using FREEWAT. With a closed and semi-arid basin, the aim of the study was to analyze the relationships between agricultural water use in the basin and water flows to Lake Tuzla. The recharge input data were estimated by the SWAT hydrological model, which indicated an average recharge of 21 million m·/year, and pumping was estimated, based on water use licenses issued by the state, at 1.49 million m°/year. The model simulated an annual recharge of 5.27 million m?, with losses of 2.25 million m°/year to the Digirmen River, 1.43 million т"/уеаг by discharge to Lake Tuzla and 1.49 million m·/year by pumping. These results show the direct impact that groundwater use in the Palas Basin has on Lake Tuzla, highlighting the need for tighter control over pumping to ensure the sustainability of the lake.
Grodzynskyi & Svidzinska (2017)studied the impact of different land use scenarios on water resource management in the Bakumivka River Basin, Ukraine. In order to find the optimal spatial distribution of water supplied to local farms by modifying the land cover pattern in the basin, the numerical model using FREEWAT was developed. Three land use scenarios were developed for comparison: a traditional scenario, with the land cover pattern of the last five years; a market-oriented scenario, with cash crops occupying 70% of the land; and an environmentally sustainable scenario, where water-intensive crops are removed and ecological corridors and permanent preservation areas are introduced. The results showed that changes in the land use pattern can be an effective measure to reduce water supply to farms, but it does not solve flooding problems in lowland areas or drought problems in sandy soils.
Kopac & Vremec (2017)used hydrogeological and water quality monitoring data provided by local water supply companies and environmental agencies to simulate the Vrbanski Plato aquifer in Slovenia with FREEWAT. The main objective of the study was to analyze the interaction between the surface waters of the Drava River and the groundwater of the aquifer, as well as to assess its vulnerability to urban contamination, due to its proximity to the city of Maribor. The results showed that artificial recharge is effective in controlling pollution from the city and increasing the capacity of the system. Furthermore, even in unfavorable situations, the proportion of contaminated water still remains within acceptable limits.
The study Manea (2020)addressed the sustainable exploitation of the alluvial phreatic aquifer of the Buzau River, in Romania, using groundwater flow modeling with FREEWAT to assess the impacts of overexploitation. In order to determine the maximum flows that can be extracted without causing overexploitation of the aquifer, the author simulated the region in steady and transient states, to analyze the impact of continuous exploitation of the aquifer over 10 years. The results showed that the maximum allowable flows range from 4 to 19 Изт depending on the location of the extraction wells. Wells located close to the Calmatui River presented higher flows due to the continuous recharge of the river. In addition, it was observed that after 10 years of continuous pumping, the aquifer depression cone reached a diameter of 9.8 km, with a maximum drawdown of 8.26 m.
Sapiano et al. (2017)used FREEWAT in a freshwater aquifer at sea level on the island of Gozo, Malta, which is suffering from overexploitation. The model developed focused on assessing the impacts of groundwater management strategies developed in the River Basin Management Plan for the region. In addition, scenarios considering the effects of climate change on the aquifer were also implemented. The results showed that the plan's proposals would lead to an improvement in the aquifer's condition, which would reach a "good state" by 2021. However, saltwater intrusion into the aquifer proved to be a critical problem, especially in areas with a high density of public water supply wells.
Another study that focused on the application of numerical flow modeling using FREEWAT to analyze aquifers suffering from overexploitation was that of Positano & Nannucci (2017). The authors studied the Follonica-Scarlino aquifer, located in a coastal plain in southern Tuscany, Italy. As in the study by Sapiano ег al. (2017), the focus was to evaluate the measures proposed in the local basin management plan for improving the quantitative state of the aquifer. The construction of the model adopted a participatory approach, involving local representatives from different sectors, to identify problems, select scenarios and evaluate the proposed solutions. The results showed the need for continuous monitoring of the aquifer, with the installation of more automatic stations to improve the calibration of the model. In addition, they proposed the reuse of water from a local mine, which showed great potential to improve the sustainability of the aquifer.
Koltsida & Kallioras (2019)applied FREEWAT to simulate groundwater flow in a coastal aquifer system located in the southwestern Rhodope region of northern Greece. The model implemented using MODFLOW 2005 simulated two stress periods: a steady state lasting one day and a transient state lasting 181 days, during which 411 pumping wells were activated. Sensitivity and calibration analysis used UCODE 2014, and focused on parameters such as hydraulic conductivity, specific storage and direct recharge from precipitation. After calibration, the model presented a NS of 0.74 and a mass balance error of 0.80, indicating that the simulated values were slightly higher than the observed ones.
Perdikaki et al. (2022)proposes the use of a participatory approach to develop a groundwater management model in the Marathon coastal plain, Greece, focusing on managed aquifer recharge (MAR). The region faces groundwater salinization problems due to saltwater intrusion, over-extraction and agricultural activities. The use of the FREEWAT platform allowed the modeling of groundwater flow and solute transport, through the SEAWAT code for variable density flow simulation. The results showed that the application of MAR achieved a significant reduction in salinity. In addition, it demonstrated that participatory modeling can be an effective tool to ensure sustainable aquifer management.
Menichini & Doveri (2020)carried out modeling of the coastal aquifer system of the Versilia region in Tuscany, Italy. In order to evaluate the groundwater components and the possible effects of extreme weather events on the aquifer, the groundwater flow model was simulated using the MODFLOW code in the FREEWAT platform. The results highlighted the importance of rivers and alluvial deposits in the recharge of coastal aquifers such as the Versilia River, which is a crucial component for the protection of the aquifer against saltwater intrusion. Extreme events, such as heavy rainfall, have shown to be a real threat to the aquifer, reducing recharge and increasing its vulnerability to saline intrusion.
Khaled et al. (2021)used FREEWAT to simulate groundwater flow and calculate the water balance of the Bouteldja coastal aquifer, located in northeastern Algeria. The water balance showed that, in addition to recharge by precipitation, exchanges with surface water bodies and the adjacent alluvial aquifer contribute significantly to aquifer recharge. The model was manually calibrated, adjusting parameters such as hydraulic conductivity and recharge rates, using piezometric measurements from May 2018. This data limitation, both temporally and spatially, resulted in areas where the model was unable to simulate flow directions and piezometric levels accurately.
3.2 REFERENCE NETWORK AND AUTHORS
The 22 articles were published in fifteen journals. Approximately 86% of the publications were published after 2017, reinforcing the innovation and recent relevance of the platform, as shown in Figure 2. The number of citations and thematic patterns are shown in Table 1.
Using the CiteSpece software, it is possible to identify relevant information regarding the articles analyzed. The analysis of the reference network allows the identification of the most cited works and their degree of centrality, a parameter provided by the software itself that 1s associated with the path taken by the information in large groups. Thus, the 22 articles were analyzed together with the references contained in them, generating a co-citation network and counting how many times each article was cited in this network.
The most cited study in terms of citation frequency was Rossetto et al. (2018), with 74 citations, which presents and discusses all the tools included in the FREEWAT platform. The studies with the greatest centrality wereCannata et al. (2018) and De Filippis et al. (2020), Which discuss applications of the platform's tools in different aquifers.
Similar to the reference network, the author network identifies the influence of the author on a research field, reinforcing the importance of the names that are present in the most prominent references. The most cited authors considering the frequency of citations were Rossetto R. and De Filippis G., while the authors with the greatest centralities were De Filippis G. and Criollo R.
Rossetto R. is the lead author of three papers, including the most cited paper (Rossetto et al., 2018; Rossetto et al., 2015, 2019), and a contributor to six (Arce et al., 2023; Cannata et al., 2016, 2018; Criollo et al., 2019; De Filippis et al., 2017, 2020). De Fillipis G. is the lead author of two papers, one with 20 (De Filippis et al., 2017)and the other with 21 citations (De Filippis ег al., 2020), and a contributor to two (Rossetto et al., 2018; Rossetto et al., 2019).
4 CONCLUSION
One of the major challenges facing water resources today is the development of management plans that promote environmental sustainability. Given the impact of climate change on the quality and quantity of available water, tools that allow the creation of scenarios and analyses of the situation of groundwater are not only of theoretical or academic importance. They directly influence the quality of life of the population.
The FREEWAT platform is an attractive option for applications in both simple and complex systems. Its integration with QGIS and the existence of several modules that allow the simulation of underground flow, saltwater intrusion, the influence of different land uses on groundwater, among others, facilitate the development of a complex and robust database, capable of adequately characterizing the aquifer.
This review analyzed the state of the art on the FREEWAT platform and concluded that, although the platform needs to be further explored, it is fully viable and can be implemented for a wide range of purposes.
Future trends of FREEWAT should be directed towards increasing the quality and quantity, both spatially and temporally, of the input data required for simulation, as it is one of the main problems found in the literature.
ACKNOWLEDGMENTS
The authors would like to thank the funding agency CAPES for the doctoral scholarship granted, thus providing support for the development of scientific and technological advancement in the area of the present study.
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Abstract
Objective: The objective of this study is to investigate the existing literature on the development and application of the FREEWAT platform as a tool for groundwater modeling, addressing the technical implications and limitations that the technical-scientific community has studied so far. Method: The methodology adopted for this review comprises the application of the PRISMA method. The search term "FREEWAT" was used in the Web of Science and Scopus databases. Based on the studies found, the PRISMA method divides the systematic review process into four stages: identification, selection, eligibility, and inclusion. The articles that met the eligibility criteria were subjected to bibliometric analysis using the CiteSpace software, enabling the visualization of new trends and existing gaps in the scientific literature on the topic. Results and Discussion: A total of 22 articles were analyzed, highlighting studies on the application of FREEWAT in coastal aquifers, along with the addition of different tools to the platform. The results indicate that FREEWAT is still underutilized, especially outside Europe. However, its application is highly viable. Future research should aim to deepen its capacity for representing complex systems, as well as improving the quality and quantity of input data used to ensure greater reliability of the results obtained. Research Implications: The use of the FREEWAT platform is an attractive option for applications in both simple and complex systems. Its integration with QGIS software and the availability of multiple simulation modules facilitate the development of a complex and robust database for groundwater modeling. Originality/Value: FREEWAT is a free and open-source platform that stands out due to its integration of numerical simulation models for groundwater systems, such as MODFLOW, with the QGIS software environment. This integration is valuable for supporting planning, management, and monitoring activities of these systems. Therefore, this study contributes to the existing literature by conducting a comprehensive review of FREEWAT's use, providing valuable insights into its application in systems with different characteristics, and identifying key trends, influential studies, and emerging research areas.