Managed aquifer recharge (MAR) is the purposeful recharge of an aquifer for later recovery or environmental benefits and represents a valuable method for sustainable water resources management. Models can be helpful tools for the assessment of MAR systems. This review encompasses a survey and an analysis of case studies which apply flow and transport models to evaluate MAR. The observed modeling objectives include the planning or optimization of MAR schemes as well as the identification and quantification of geochemical processes during injection, storage and recovery. The water recovery efficiency and the impact of the injected water on the ambient groundwater are further objectives investigated in the reviewed studies. These objectives are mainly solved by using groundwater flow models. Unsaturated flow models, solute transport models, reactive geochemical models as well as water balance models are also frequently applied and often coupled. As each planning step to setup a new MAR facility requires cost and time investment, modeling is used to minimize hazard risks and assess possible constraints of the system such as low recovery efficiency, clogging and geochemical processes.

Managed aquifer recharge (MAR) is the purposeful recharge of an aquifer for later recovery or environmental benefits and represents a valuable method for sustainable water resources management. Models can be helpful tools for the assessment of MAR systems. This review encompasses a survey and an analysis of case studies which apply flow and transport models to evaluate MAR. The observed modeling objectives include the planning or optimization of MAR schemes as well as the identification and quantification of geochemical processes during injection, storage and recovery. The water recovery efficiency and the impact of the injected water on the ambient groundwater are further objectives investigated in the reviewed studies. These objectives are mainly solved by using groundwater flow models. Unsaturated flow models, solute transport models, reactive geochemical models as well as water balance models are also frequently applied and often coupled. As each planning step to setup a new MAR facility requires cost and time investment, modeling is used to minimize hazard risks and assess possible constraints of the system such as low recovery efficiency, clogging and geochemical processes.

Esta tese apresenta um estudo da integração das características geológico geotécnicas da região de São Carlos que condicionam o processo de recarga do aquífero constituído pelos arenitos da Formação Botucatu. Dentre as características avaliadas, destacam-se os parâmetros de condutividade hidráulica, de retenção de poluentes e de distribuição de poros, além das informações sobre a distribuição e ocorrência dos materiais geológicos, profundidade do nível de água, uso do solo e superfícies de difração hídrica. Tais informações foram obtidas a partir de trabalhos integrados de escritório, campo e laboratório, sendo os resultados gerados na forma de mapas considerados fundamentais para a elaboração de modelos destinados à avaliação de recarga. Foi também realizado na região monitoramento pluviográfico das chuvas, bem como dos níveis de água e de umidade da zona não saturada através de poços e tensiômetros, respectivamente. As informações integradas e os dados de monitoramento foram utilizados em simulações no programa Mike-She, que considerou os diferentes aspectos geológico-geotécnicos no estudo de avaliação das taxas de recarga. O estudo demonstrou a importância da variabilidade dos materiais geológicos, das características geológico-geotécnicas e da dinâmica das águas para a adequada avaliação das taxas de recarga de aqüífero e de fluxo dos poluentes. / This thesis presents an integrated study of the geological and geotechnical characteristics of São Carlos region which influence the recharge process of the aquifer composed of sandstones of the Botucatu Formation. Among the assessed characteristics, it can be distinguished the parameters of ydraulic conductivity, retention of pollutants and pore distribution, also information about the distribution and occurrence of the geologic materials, groundwater depth, land use and water diffraction surfaces. Such data were obtained from desk study, field and laboratory integrated works, with the results being generated in the form of maps considered fundamental to the development of models for recharge assessment. In the region, it was also conducted monitoring of rainfall, groundwater levels and water content of the unsaturated zone through pluviograph, monitoring wells and tensiometers, respectively. The integrated information and monitoring data were used in the Mike-She software simulations, which considered the different geological and geotechnical aspects in the study for assessment of the recharge rates. The study demonstrated the importance of variability of geological materials, geological and geotechnical characteristics and dynamics of water for the adequate assessment of the aquifer recharge and transport of pollutants.

Esta tese apresenta um estudo da integração das características geológico geotécnicas da região de São Carlos que condicionam o processo de recarga do aquífero constituído pelos arenitos da Formação Botucatu. Dentre as características avaliadas, destacam-se os parâmetros de condutividade hidráulica, de retenção de poluentes e de distribuição de poros, além das informações sobre a distribuição e ocorrência dos materiais geológicos, profundidade do nível de água, uso do solo e superfícies de difração hídrica. Tais informações foram obtidas a partir de trabalhos integrados de escritório, campo e laboratório, sendo os resultados gerados na forma de mapas considerados fundamentais para a elaboração de modelos destinados à avaliação de recarga. Foi também realizado na região monitoramento pluviográfico das chuvas, bem como dos níveis de água e de umidade da zona não saturada através de poços e tensiômetros, respectivamente. As informações integradas e os dados de monitoramento foram utilizados em simulações no programa Mike-She, que considerou os diferentes aspectos geológico-geotécnicos no estudo de avaliação das taxas de recarga. O estudo demonstrou a importância da variabilidade dos materiais geológicos, das características geológico-geotécnicas e da dinâmica das águas para a adequada avaliação das taxas de recarga de aqüífero e de fluxo dos poluentes. / This thesis presents an integrated study of the geological and geotechnical characteristics of São Carlos region which influence the recharge process of the aquifer composed of sandstones of the Botucatu Formation. Among the assessed characteristics, it can be distinguished the parameters of ydraulic conductivity, retention of pollutants and pore distribution, also information about the distribution and occurrence of the geologic materials, groundwater depth, land use and water diffraction surfaces. Such data were obtained from desk study, field and laboratory integrated works, with the results being generated in the form of maps considered fundamental to the development of models for recharge assessment. In the region, it was also conducted monitoring of rainfall, groundwater levels and water content of the unsaturated zone through pluviograph, monitoring wells and tensiometers, respectively. The integrated information and monitoring data were used in the Mike-She software simulations, which considered the different geological and geotechnical aspects in the study for assessment of the recharge rates. The study demonstrated the importance of variability of geological materials, geological and geotechnical characteristics and dynamics of water for the adequate assessment of the aquifer recharge and transport of pollutants.

Les facteurs qui régissent l'intensité et la répartition de la recharge naturelle et artificielle dans les aquifères cristallins altérés et fracturés sont mal connus. Ce sont cependant les caractéristiques déterminantes de ce type de roche—ces roches sont très hétérogènes—qui rendent difficile l’estimation des flux dans ces milieux ainsi que des propriétés hydrauliques qui les contrôlent. La première partie de ce manuscrit fournit un état des connaissances sur la recharge des eaux souterraines et ses méthodes d’estimation, permettant de comprendre les défis scientifiques et sociétaux abordés dans cette thèse. La deuxième partie présente les travaux numériques et expérimentaux menés pour approfondir notre compréhension de la dynamique des flux d’eaux souterraines dans ces milieux hétérogènes à plusieurs échelles. Le premier axe de recherche porte sur les processus de recharge naturelle à l’échelle du bassin versant. La recharge diffuse a été modélisée avec un modèle physique simple d’infiltration et comparée à des estimations préalables de recharge totale. Nos résultats illustrent la forte dépendance de la recharge aux précipitations et à l’irrigation, et l’importance de la recharge focalisée. Les facteurs responsables de la distribution spatiale de la recharge sont aussi étudiés. Le deuxième axe est basé sur le suivi de la mise en eau d’un bassin de recharge artificielle dans un site hautement monitoré et bien équipé. Ces observations ont été interprétées avec des modèles analytiques et numériques. Ces modèles ont mis en évidence l’existence de flux préférentiels horizontaux, mais aussi d’une compartimentation latérale qui entrave la propagation des intrants de recharge. / The factors governing the intensity and distribution of natural and artificial recharge in weathered and fractured crystalline aquifers are poorly understood. However, it is the defining characteristics of this type of rock—these rocks are very heterogeneous—that make the estimation of fluxes and the hydraulic properties controlling them difficult. The first of its two parts provides the theoretical framework on groundwater recharge processes and its estimation methods for comprehending the scientific and societal challenges discussed in this thesis. The second part presents the numerical and experimental work carried out to deepen our understanding of the dynamics of groundwater flows in these heterogeneous underground environments at several scales. The first line of research focuses on natural recharge processes at the watershed scale. Diffuse recharge was modeled with a simple physical infiltration model and compared to previous estimates of total recharge. Our results highlight the strong dependence of recharge on rainfall and irrigation, and the importance of focused recharge. The factors responsible for the spatial distribution of recharge are also studied. The second axis is based on the monitoring of the filling of an artificial recharge basin at a highly monitored and well-equipped site. These observations were interpreted with analytical and numerical models to improve our knowledge of flow dynamics in fractured crystalline rocks at the medium scale. These models illustrated the existence of preferential horizontal flows, but also of a lateral compartmentalization that hinders the propagation of recharge inputs.

Managed aquifer recharge (MAR) is a low-energy subsurface water treatment system with the potential of being an important component of sustainable water reuse schemes. Alongside common wastewater contaminants, MAR systems have been shown to attenuate a range of trace organic chemicals (TOrCs). Despite several factors being possibly important for TOrC attenuation, many have not been investigated in depth. This research effort investigated three factors affecting attenuation of the moderately degradable TOrCs: primary substrate, adaptation of the microbial community to presence of TOrCs, and groundwater temperature. The overall goal was to optimize TOrC attenuation using different MAR configurations considering how these factors affect TOrC attenuation. The primary substrate composition and concentration significantly impacted attenuation of the moderately degradable TOrCs. Lower primary substrate concentrations and more refractory carbon generally resulted in better TOrC transformation, a more diverse microbial community in the infiltration zone and more diverse capabilities for TOrC degradation. The enzyme group cytochrome P450 may be important for TOrC transformation since its genes were more abundant under carbon-starving primary substrate conditions. Adaptation of the microbial community by pre-exposure to TOrCs was not required in order to degrade them. However, adaptation to the primary substrate was necessary for TOrC biotransformation due to its effect on the microbial community. Attenuation of most TOrCs was unaffected by changes in temperature. Some moderately degradable TOrCs, however, were better attenuated at higher temperatures likely due to increased microbial activity. Others were better degraded at lower temperatures likely due to favorable sorption conditions. In the context of applying MAR systems to potential water reuse schemes within Saudi Arabia, a reconnaissance study of TOrC occurrence in treated wastewater effluents was undertaken. Most of the TOrCs targeted were detected at similar concentrations to US effluents at comparable plants. One of the plants studied, however, displayed a significantly different TOrC footprint from the other treatment plants due to the large number of international visitors in its sewershed. Findings from this occurrence study as well from other tasks provided inputs to a risk assessment framework to compare the effectiveness of MAR systems as part of a multiple-barrier water reuse scheme.

No description available.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The intention in this work is to study (locally) the fluctuation system of groundwater levels in two small watersheds. We selected Rancho do Amaral and Rincão do Soturno small watersheds for being representative of the first order streams which compose the Vacacaí-Mirim river watershed headwaters. Both are located at the border of Paraná Sedimentary Basin, in the central region of the state of Rio Grande do Sul. These small watersheds belong to the municipalities of Itaara and Santa Maria, and they are contributors of the Brazilian hydrographic region South Atlantic. They are considered exceptionally important for the municipality of Santa Maria because they are the main drinking water sources for the DNOS Dam at the Vacacaí-Mirim river. They belong to the system in which water is accumulated and provided to the population. The area under study is part of overlying sandstone in the Botucatu Formation, which belongs to the Guarani Aquifer System. In order to carry out the studies, three monitoring wells were made with equipment measuring the water levels and atmospheric pressure. The equipment was set to automatically take readings every hour. Based on the date collected from the equipment, we mounted a database and applied it to a specific computer program, which allowed us to adopt the Water Table Fluctuation (WTF) method. This method only applies to unconfined aquifers and measures direct groundwater recharges in drainage basins. The recharge was estimated to be 833.0 mm at well number 5; 746.2 mm at well number 6 and 467.2 mm at well number 7 during the period of evaluation. Therefore, the presence of groundwater recharge confirmed our work hypothesis. / A intenção neste trabalho foi de estudar, na situação local, o sistema de flutuação dos níveis de água subterrânea em duas microbacias hidrográficas. Foram selecionadas as microbacias Rancho do Amaral e Rincão do Soturno , por serem representativas de curso de água de primeira ordem, fazendo parte das cabeceiras da bacia hidrográfica do Rio Vacacaí-Mirim. Ambas situadas na borda da Bacia Sedimentar do Paraná, compreendendo a região central do Estado do Rio Grande do Sul. Estas microbacias pertencem aos municípios de Itaara e Santa Maria, e são contribuintes da região hidrográfica brasileira Atlântico Sul. Consideram-se excepcionalmente importantes para o município de Santa Maria/RS, pois são as principais fornecedoras de água potável para a barragem do DNOS, no Rio Vacacaí-Mirim, pertencente ao sistema de acumulação e distribuição de água à população. A área em estudo faz parte de afloramentos de arenitos da Formação Botucatu pertencentes ao Sistema Aquífero Guarani. Para a execução do estudo foram perfurados 3 (três) poços de monitoramento e neles instalados equipamentos de medição de nível de água e de pressão atmosférica, que são automáticos e configurados para realizarem leituras de hora em hora. Com base nos dados obtidos pelos equipamentos montou-se um banco de informações, que, aplicadas a um programa de computador específico, permitiram a adoção do método WTF (Water Table Fluctuation). Este método somente se aplica a aquífero livre e determina a recarga direta dos mananciais de água subterrânea. Estimou-se a recarga em 833 mm no Poço 5; 746,2 mm no Poço 6 e 467,2 mm no Poço 7, durante o período avaliado. A hipótese de trabalho foi comprovada, indicando haver recarga de água subterrânea.

Submitted by Lucienne Costa (lucienneferreira@ufcg.edu.br) on 2018-04-13T17:55:28Z No. of bitstreams: 1 JOÃO DEHON DE ARAÚJO PONTES FILHO – DISSERTAÇÃO (PPGECA) 2018.pdf: 3164932 bytes, checksum: ca3f762e9350a916f6bb046e39613cd8 (MD5) / Made available in DSpace on 2018-04-13T17:55:28Z (GMT). No. of bitstreams: 1 JOÃO DEHON DE ARAÚJO PONTES FILHO – DISSERTAÇÃO (PPGECA) 2018.pdf: 3164932 bytes, checksum: ca3f762e9350a916f6bb046e39613cd8 (MD5) Previous issue date: 2018-02-07 / Grande parcela dos escassos recursos hídricos do semiárido brasileiro estão armazenados nos aquíferos aluviais, servindo como importante fonte para o abastecimento de comunidades rurais e a irrigação de pequeno porte, diante da intermitência dos rios da região. Apesar da importância desses aquíferos, esgoto doméstico, tratado ou não, é depositado nos leitos secos desses rios, gerando uma recarga não gerenciada desses aquíferos que pode provocar impactos negativos, fato que demanda a criação de estratégias em busca de possibilitar o correto manejo desse sistema. Uma opção é realizar a recarga gerenciada desses aquíferos, aproveitando-se da infraestrutura hídrica existente, formada por barragens associadas aos sistemas de tratamento de esgoto. Para formulação de tal estratégia nesse estudo, buscou-se um local que possuísse características representativas da região. Foram levantados dados litológicos e monitorados o nível estático e a qualidade da água do aquífero, assim como sua relação com a precipitação. Dessa forma, o sistema, formado pelo aquífero do Rio Sucuru, o açude Sumé e o esgoto produzido pela cidade de Sumé-PB, foi estudado e observou-se que a concentração de cloreto, utilizado como traçador para indicar a presença de esgoto, manteve-se elevada na zona urbana, devido à falta de saneamento. Porém, tanto seus valores, como a variação deles ao longo do tempo, vão diminuindo com o transcorrer do fluxo subterrâneo. Ainda, em busca de entender a efetividade do tratamento solo-aquífero na região, comparou-se as análises de nutrientes e de indicador bacteriológico do poço com maior presença de cloreto e do esgoto tratado, obtendo-se resultados melhores para o efluente após passagem pelo solo do que pelo sistema de lagoas de estabilização. Apesar dessa aparente capacidade de tratamento do aquífero para tais parâmetros, o mesmo não possui capacidade de remoção de cloreto, o que mostra a necessidade de realizar recarga com águas de menores concentrações, objetivando garantir seus usos e evitar risco de salinização. Diante disso, a estratégia proposta foi dividida em quatro medidas, duas utilizando o esgoto e duas recursos hídricos superficiais, as quais consideram os desafios financeiros e operacionais que podem surgir, de modo a promover: (i) reuso de águas servidas, (ii) diminuir as perdas por evaporação, e, consequentemente, (iii) aumentar a oferta. Sendo assim, essa proposta de promoção da gestão integrada dos recursos hídricos da região atuará no sentido de atingir os objetivos de desenvolvimento do milênio. / Great amount of scarce water resources from Brazilian semiarid are stored at alluvial aquifers, serving as important source to supply rural communities and small irrigation, due to its intermittent rivers. Despite the importance of this aquifers, wastewater, treated or not, is disposed at dry riverbed, generating an un-managed aquifer recharge that can lead to negative impacts, demanding creation of strategy searching for correct management of this system. One option is to manage recharge this aquifers, taking advantage of hydric works, made by dams, in conjunction with treated wastewater. To formulate this strategy, a site that possess representative characteristics of the region was chosen, in which lithologic data and of water quality and hydraulic heads were monitored, as their relationship with precipitation. Therefore, the system made by Sucuru River, Sumé Dam and wastewater produced by the city of Sumé, in the State of Paraíba, were studied. It was observed that chloride concentration, used as a tracer to indicate wastewater presence due to lack of sanitation, kept high at the urban zone. However, its values and variation with time decrease along the aquifer. Seeking to understand the effectivity of soil-aquifer treatment, the presence of nutrients and bacteriological indicator were compered between the well with highest amount of chloride and the effluent of the wastewater treatment plant and better results were found for the passage of wastewater through the soil than the system composed by stabilization lagoons. Despite this apparent capacity of treatment from the aquifer, it cannot remove chloride, demonstrating the need to use water with less concentration of this parameter in order to secure its uses and avoid salinization hazard. In face of that, the proposed strategy was divided in four measures, two utilizing wastewater and two superficial water resources available and they consider financial and operational challenges that may occur, in order to promote: (i) water reuse, (ii) reduce evaporation losses and, consequently, (iii) increase offer. This proposal to promote integrated management of existing water resources will act to achieve millennium development goals.

The current pressure on water resources is such, that water scarcity is now an important issue in regions with abundant water resources like the Tropics. These regions are characterized by high precipitation rates almost all year long. This results in a relatively large availability of water resources. However, these water resources are not always equally distributed in time or space, which causes periods and puts areas under water stress in tropical regions. Added to this is the challenge related to the access to these water resources, resulting in a reduced availability in general terms. Costa Rica is a clear example of a country in the Tropical regions, where water scarcity is, actually, on the top of the water agenda. Costa Rica is in the torrid tropical region in Central America, yet it experiences periods of shortage in its available water resources at the end of the dry season. This affects all water sectors, specially agriculture and drinking water supply systems. This situation has been magnified by global change, with a greater demand of resources from population growth, impermeabilization of recharge areas due to urbanization, and reduction of resources due to climate change. To adapt to the situation, it is necessary to conduct an evaluation of suitable water management tools for the country’s environmental conditions in a systematic way. This work focuses on one of these tools: managed aquifer recharge (MAR) MAR techniques are a promising approach to address the defined problems, by storing the excess of available water resources during the rainy season in suitable aquifer systems for later use during the dry season. MAR techniques present certain advantages compared to surface storage: less losses through evaporation, less demand of superficial area, among others. In order to determine if MAR techniques are suitable for Costa Rica and will help overcome the temporary water scarcity challenge, three main topics at different scale are investigated. First, at a country scale, the search of suitable areas for specific MAR techniques within the country is carried out based on physical criteria. Second, at a research scale, it is reduced to a basin level. For this case, the assessment of a MAR project based on the first stage of the Australian MAR guidelines is done. This consists of a checklist of five critical elements, which constitutes the base for the assessment of a MAR project. Third, the research is taken into a laboratory scale, where the research focuses on an injection well in an unconfined aquifer system. For the first topic, suitable areas for the implementation of MAR technique spreading methods are identified in Costa Rica by conducting a geographical information science-multi-criteria decision analysis (GIS-MCDA) approach. This is based on four criteria: hydrogeological geoaptitude, terrain slope, top soil texture, and drainage network density. By carrying out a GIS-MCDA, the country is classified into suitable and unsuitable. Based on this method, 61 % of the country is suitable for spreading methods. Among the higher ranked suitable areas are the ones located in the northern and northwest regions. The ranking of the country based on spreading methods by means of a GIS-MCDA method is a first course of action to determine where further research is needed. In the second research level, the feasibility of a MAR project was assessed in the Machuca River basin. This river basin was chosen because: the drinking water supply systems (WSS) do not meet the actual demand, there is government interest to research new water supply alternatives and there is enough basic information on this water basin. To evaluate the feasibility of a MAR project in the basin, the first stage of the feasibility assessment proposed by the Australian MAR guidelines was performed. This consists of a checklist of five critical elements: 1) sufficient demand, 2) adequate recharge source, 3) suitable aquifer, 4) space to treat and, 5) human capability. For an easier analysis of the whole river basin, it was divided into five locations based on the superficial aquifer water levels. It was concluded that a MAR project seems viable in this river basin in the Coyolar and Orotina locations. Regarding the MAR technique to be applied in the MAR project at the Machuca River basin, two considerations were taken: the previously determined suitability and the local conditions. First, the entire Machuca River is ranked as suitable for surface infiltration (MAR spreading method) based on the results from the country scale analysis. The Coyolar and Orotina locations are ranked as having a moderate suitability (between 0.4-0.6). Second, the best material aquifer for recharge in these two locations are the fractured lavas and alluvium located under clay layers. For these two reasons (moderate spreading methods suitability and local conditions), it was decided that direct injection MAR techniques (aquifer storage and recovery – ASR) will be more appropriate for these two locations. At the laboratory research scale, the effect of the well screen length on the injection rate for an unconfined aquifer was corroborated under controlled laboratory conditions. This is one of the first experiments on the topic to the best of the author’s knowledge. One of the main findings of the laboratory research is the almost neglectful effect on the injection rate for screen lengths above 80 % of the saturated thickness in an unconfined aquifer. The effect on the screen length is notable in the injection rate for open screen length under 80 % of the total aquifer thickness (95 % of the maximum achievable injection rate) and it increases for open screen lengths under 40 % (90 % of the maximum achievable injection rate). Based on the experimental results, it is recommended to use a screen length of 40 % of the saturated aquifer thickness for ASR wells and of 80 % for injection wells. This assessment shows that MAR techniques are suitable for Costa Rica’s environmental conditions. Further on, the assessment at the basin level shows MAR techniques as a promising solution to overcome water scarcity issues. The laboratory scale aquifer-well interactions show promising results regarding the effect of the screen well in the injection rate. Still, more research is needed in this field regarding other aquifer types. Based on all these findings, MAR techniques are an appropriate tool for the integrated water management in the tropical regions. / Der gegenwärtige Druck auf die Wasserressourcen ist so groß, dass Wasserknappheit sogar in den Tropen zum Thema wird. Diese Regionen sind von hohen Niederschlagsraten geprägt, was zu einer relativ großen Verfügbarkeit von Wasserressourcen führt. Diese sind jedoch nicht immer zeitlich und räumlich gleich verteilt, was temporären und/oder regionalen Wasserstress verursacht. Darüber hinaus hängt die Herausforderung auch mit dem Zugang zu diesen Wasserressourcen zusammen, was zu einer allgemein reduzierten Verfügbarkeit führt. Costa Rica ist ein Beispiel für ein tropisches Land, in dem Wasserknappheit in den letzten Jahren zunehmend an Relevanz gewonnen hat. Costa Rica leidet gegen Ende der Trockenzeit fast jedes Jahr an einem temporären Wassermangel. Dies betrifft alle Wassersektoren, insbesondere die Landwirtschaft und die Trinkwasserversorgung. Diese Situation wird durch den globalen Wandel verstärkt, mit einer größeren Nachfrage nach Ressourcen aufgrund von Bevölkerungswachstum, der Verhinderung von Grundwasserneubildung durch Urbanisierung und Versiegelung und, nicht zuletzt, den Klimawandel. Um sich an diese Situation anzupassen, ist es notwendig, eine systematische Evaluierung geeigneter Wasserbewirtschaftungsinstrumente für die Umweltbedingungen des Landes durchzuführen. Die vorliegende Arbeit konzentriert sich auf eines dieser Werkzeuge: Managed Aquifer Recharge (MAR). MAR-Techniken stellen einen vielversprechenden Ansatz dar, um die zuvor definierten Probleme anzugehen, indem die überschüssigen Wasserressourcen während der Regenzeit in geeigneten Grundwasserleitersystemen zur späteren Nutzung in der Trockenzeit gespeichert werden. MAR-Techniken bieten im Vergleich zur Oberflächenspeicherung gewisse Vorteile, unter anderem geringere Verdunstungsverluste und geringeren Raumbedarf. Um zu bestimmen, ob MAR-Techniken für Costa Rica geeignet sind und dabei helfen können, die zeitlichen Wasserknappheitsherausforderungen zu überwinden, wurden drei Hauptthemen in unterschiedlichen Skalen untersucht. Die Suche nach geeigneten Gebieten für spezifische MAR-Techniken im Land erfolgte zunächst auf der Grundlage von physikalischen Kriterien. Als Zweites wurde die Forschungsskala auf ein Beckenniveau reduziert. Für diesen Fall wurde die Bewertung eines MAR-Projekts auf der Grundlage der ersten Stufe der australischen MAR-Richtlinien durchgeführt. Diese basiert auf einer Checkliste mit fünf kritischen Elementen, welche die Grundlage für die Bewertung eines MAR-Projektes bilden. Zuletzt wurde die Untersuchung im Labormaßstab durchgeführt, wobei sich die Experimente auf Injektionsbohrlöcher in einem ungespannten Grundwasserleitersystem konzentrierten. Für das erste Thema wurden in Costa Rica geeignete Bereiche für die Implementierung von MAR-Technik-Verteilungsmethoden mithilfe eines GIS-basierten Multikriterien- Entscheidungsanalysen-Ansatzes (GIS-MCDA) identifiziert. Dieser basierte auf vier Kriterien: Hydrogeologie, Geländegefälle, oberste Bodentextur und Drainagenetzdichte. Durch die Realisierung eines GIS-MCDA wurde das Land in geeignete und ungeeignete Gebiete eingeteilt. Mit dieser Methode wurden 61 % des Landes als geeignet für die Beckeninfiltration befunden. Gut eingestufte Gebiete liegen hierbei größtenteils im Norden und im Nordwesten. Das Ranking-Verfahren des Landes mit Hilfe einer GIS-MCDA-Methode ist eine erste Vorgehensweise zur Bestimmung weiterer Forschungsgebiete. In der zweiten Forschungsstufe wurde die Machbarkeit eines MAR-Projekts im Machuca-Einzugsgebiet untersucht. Dieses Flussgebiet wurde aus folgenden Gründen gewählt: Die Trinkwasserversorgungsanlagen erfüllen die tatsächliche Nachfrage nicht, weshalb es auch im Interesse der Regierung liegt, nach Alternativen für die Wasserversorgung zu forschen. Darüber hinaus ist die Region geologisch gut erschlossen und die Informationsdichte ist ausreichend hoch. Um die Realisierbarkeit eines MAR-Projektes im Einzugsgebiet zu bewerten, wurde die erste Stufe der Machbarkeitsbewertung anhand der Checkliste an fünf kritischen Elementen durchgeführt: 1) ausreichende Nachfrage, 2) angemessene Wiederaufladungsquelle, 3) geeigneter Grundwasserleiter, 4) Raum für Maßnahmen und 5) Humanressourcen. Um die Analyse des gesamten Flusseinzugsgebietes zu vereinfachen, wurde es in fünf Bereiche eingeteilt, die auf den oberflächennahen Grundwasserständen basieren. Es wurde der Schluss gezogen, dass ein MAR-Projekt in diesem Flussgebiet an den Standorten Coyolar und Orotina nachhaltig erscheint. In Bezug auf die MAR-Technik, die in einem MAR-Projekt am Machuca-Flussbecken angewendet werden soll, wurden Überlegungen angestellt hinsichtlich der zuvor ermittelten Eignung und der örtlichen Gegebenheiten. Zunächst wurde der gesamte Machuca-Fluss aufgrund der Ergebnisse der Länderanalyse als geeignet für die Oberflächeninfiltration eingestuft. Die Coyolar- und Orotina-Standorte wurden mit einer moderaten Eignung eingestuft. Weiterhin wurde festgestellt, dass die für die Grundwasseranreicherung geeignetste Formation die Kies- und Bruchlavenlagen darstellen, die sich unter einer Tonschicht befinden. Aus diesen beiden Gründen (moderate Eignung für Beckeninfiltration, und lokale Hydrogeologie) wurde entschieden, dass MAR-Techniken mit direkter Injektion (Aquifer Storage and Recovery - ASR) für diese beiden Standorte geeigneter sind. In der kleinsten Untersuchungsskala wurde der Einfluss der Filterlänge auf die Injektionsrate für einen freien Grundwasserleiter unter kontrollierten Laborbedingungen bestätigt. Dies ist eines der ersten Experimente zu diesem Thema nach bestem Wissen des Autors. Eines der Hauptergebnisse der Laborforschung ist der fast vernachlässigbare Effekt auf die Injektionsrate bei Filterlängen von über 80 % der gesättigten Mächtigkeit in einem freien Grundwasserleiter. Die Wirkung auf die Filterlänge ist bei der Injektionsrate für offene Filterlängen unter 80 % der gesamten Grundwasserleiterhöhe (95 % der maximal erreichbaren Injektionsrate) und bei offenen Filterlängen unter 40 % (90 % der maximal erreichbaren Injektionsrate). Basierend auf den experimentellen Ergebnissen wird empfohlen, eine Filterlänge von 40 % der gesättigten Grundwasserleiterhöhe für ASR-Brunnen und 80 % für Injektionsbohrungen zu verwenden. Die vorliegende Bewertung zeigt, dass MAR-Techniken für die Umweltbedingungen in Costa Rica gut geeignet sind. Darüber hinaus demonstriert die Bewertung auf der Einzugsgebietsebene MAR als eine Lösung zur Überwindung von Wasserknappheitsproblemen. Die Grundwasserleiter-Brunnen-Interaktionen im Labormaßstab zeigen vielversprechende Ergebnisse hinsichtlich der Wirkung der Filterlänge auf die Injektionsrate. Dennoch ist auf diesem Gebiet mehr Forschung in Bezug auf andere Aquifertypen erforderlich. Basierend auf all diesen Erkenntnissen sind MAR-Techniken ein geeignetes Werkzeug für das integrierte Wassermanagement in der tropischen Umwelt. / La presión actual sobre los recursos hídricos es tal, que la escasez de agua es ahora un problema importante en áreas con abundantes recursos hídricos como las regiones tropicales. Estas regiones se caracterizan por altas tasas de precipitación casi durante todo el año. Esto da como resultado una disponibilidad relativamente grande de recursos hídricos. Sin embargo, estos recursos hídricos no siempre se distribuyen equitativamente en el tiempo y el espacio, lo que causa períodos y pone áreas bajo estrés hídrico en las regiones tropicales. Además de esto, el desafío también está relacionado con el acceso a estos recursos hídricos, lo que crea una disponibilidad reducida en términos generales. Costa Rica es un claro ejemplo de un país en las regiones tropicales, donde la escasez de agua se encuentra en lo más alto de la agenda del agua. Costa Rica está situada en la región tropical tórrida de América Central, sin embargo, experimenta períodos de escasez en sus recursos hídricos disponibles al final de la estación seca. Esto afecta a todos los sectores de agua, especialmente a la agricultura y a los sistemas de suministro de agua potable. Esta situación ha sido magnificada por el cambio global, con una mayor demanda de recursos por el crecimiento de la población, la impermeabilización de las áreas de recarga por la urbanización y la reducción de recursos debido al cambio climático. Para adaptarse a esta situación, es necesario llevar a cabo una evaluación sistemática de las herramientas de gestión del agua adecuadas para las condiciones ambientales del país. Este trabajo se centra en una de estas herramientas: la gestión de la recarga acuíferos gestionados (MAR). Las técnicas de MAR son un enfoque prometedor para abordar los problemas previamente definidos, almacenando el exceso de recursos hídricos disponibles durante la estación lluviosa en sistemas acuíferos adecuados para su uso posterior en la estación seca. Las técnicas de MAR presentan ciertas ventajas en comparación con el almacenamiento en superficie: menos pérdidas por evaporación y menor demanda de área superficial, entre otras. Con el fin de determinar si las técnicas de MAR son adecuadas para Costa Rica y ayudarán a superar los desafíos temporales de escasez de agua, se investigaron tres temas principales a diferentes escalas. Primero, en una escala de país, la búsqueda de áreas adecuadas para técnicas específicas de MAR en el país se realizó con base en criterios físicos. En segundo lugar, la escala de investigación se reduce a un nivel de cuenca. Para este caso, se realizó la evaluación de un proyecto de MAR basado en la primera etapa de las directrices australianas de MAR. Esta consiste en una lista de verificación de cinco elementos críticos, que constituye la base para la evaluación de un proyecto MAR. En tercer lugar, la investigación se lleva a escala de laboratorio, donde la investigación se centra en los pozos de inyección en un sistema acuífero no confinado. Para el primer tema, las áreas adecuadas para la implementación de los métodos de infiltración de la MAR se identifican en Costa Rica mediante un enfoque de ciencia la información geográfica y análisis de decisión multicriterio (SIG-MCDA). Esto se basa en cuatro criterios: geoaptitud hidrogeológica, pendiente del terreno, textura del suelo superior y densidad de la red de drenaje. Al realizar un GIS-MCDA, el país se clasifica en áreas adecuadas e inadecuadas. Con base en este método, el 61 % del país se consideró adecuado para métodos de infiltración. Las áreas adecuadas mejor clasificadas se encuentran en las regiones del norte y noroeste del país. La clasificación del país según el potencial de los métodos de infiltración por medio de un método GIS-MCDA es un primer curso de acción para determinar otras áreas de investigación. En el segundo nivel de investigación, se evaluó la factibilidad de un proyecto MAR en la cuenca del río Machuca. Esta cuenca hidrográfica se eligió porque: los sistemas de suministro de agua potable no satisfacen la demanda real, existe un interés del gobierno en buscar nuevas alternativas de suministro de agua y hay suficiente información básica en esta cuenca hidrográfica. Para evaluar la factibilidad de un proyecto MAR en la cuenca, la primera etapa de la evaluación se realizó sobre la base de la lista de cinco elementos críticos: 1) demanda suficiente, 2) fuente de recarga adecuada, 3) acuífero adecuado, 4) espacio para tratar el agua y, 5) la capacidad humana. Para facilitar el análisis de toda la cuenca del río, se dividió en cinco localidades en función de los niveles de agua superficiales del acuífero. Se concluyó que un proyecto MAR parece viable en esta cuenca en las localidades Coyolar y Orotina. Con respecto a la técnica de MAR que se aplicará en un proyecto MAR en la cuenca del río Machuca, se tomaron dos consideraciones: la idoneidad previamente determinada y las condiciones locales. En primer lugar, todo el río Machuca se clasifica como adecuado para la infiltración superficial (método de infiltración MAR) en función de los resultados del análisis a escala de país. Las localidades Coyolar y Orotina se clasifican con una idoneidad moderada. En segundo lugar, el mejor material acuífero para la recarga en estos dos lugares son las fracturas lavas y aluviones ubicados bajo capas de arcilla. Se decidió que las técnicas de inyección directa MAR (almacenamiento y recuperación - ASR) serán más apropiadas para estas dos ubicaciones por estas dos razones (idoneidad de los métodos de propagación moderada y condiciones locales). En la escala de investigación más pequeña, el efecto de la longitud de la pantalla del pozo sobre la tasa de inyección para un acuífero no confinado se corroboró bajo condiciones de laboratorio controladas. Este es uno de los primeros experimentos sobre el tema según el mejor conocimiento del autor. Uno de los principales hallazgos de la investigación de laboratorio es el efecto casi nulo en la tasa de inyección para longitudes de pantalla superiores al 80 % del espesor saturado en un acuífero no confinado. El efecto en la longitud de la pantalla es apreciable en la velocidad de inyección para pantalla abierta inferior al 80 % del espesor total del acuífero (95 % de la máxima velocidad de inyección alcanzable) y aumenta para longitudes de pantalla abierta por debajo del 40 % (90 % de la máxima tasa de inyección alcanzable). En base a los resultados experimentales, se recomienda utilizar una longitud de malla del 40 % del espesor del acuífero saturado para los pozos ASR y del 80 % para los pozos de inyección. La presente evaluación muestra que las técnicas de MAR son adecuadas para las condiciones ambientales de Costa Rica. Más allá, la evaluación a nivel de cuenca muestra las técnicas de MAR como una solución para superar los problemas de escasez de agua. Las interacciones entre acuíferos y pozos a escala de laboratorio muestran resultados prometedores con respecto al efecto de la pantalla en la velocidad de inyección. Aun así, se necesita más investigación en este campo con respecto a otros tipos de acuíferos. Con base en todos estos hallazgos, las técnicas de MAR son una herramienta apropiada para la gestión integrada del agua en las regiones tropicales.