Entre os principais métodos construtivos de barragens de contenção de rejeitos de mineração, o método da linha de montante é sem dúvida o mais vulnerável à ocorrência de acidentes originados por forças de percolação da água pelo barramento. Em um sistema barragem-reservatório constituído de solos finos e de baixa coesão, como as barragens de contenção de rejeitos, as forças de percolação da água favorecem a instalação de processos erosivos internos de piping e liquefação, maiores responsáveis pelos acidentes já registrados. Para redução dos riscos de acidentes em barragens construídas pelo método da linha de montante, a avaliação do comportamento do nível dágua deve ser constante. Neste contexto, o trabalho apresenta um programa de instrumentação e monitoramento composto por medidas piezométricas, pluviométricas, de vazão, do nível dágua do reservatório e de deslocamento horizontal com marco topográfico, com vistas ao aumento do fator de segurança destas obras. A execução de um procedimento metodológico com base no programa de instrumentação e monitoramento acima citado, possibilita a avaliação do comportamento do nível dágua nestas barragens. Por fim, são descritos os aspectos relevantes para correlação dos dados da instrumentação com os valores-limite definidos para o projeto, critério este determinante para o sucesso de um programa de instrumentação. O procedimento metodológico apresentado se mostrou eficiente na obtenção de parâmetros indispensáveis a uma correta avaliação do comportamento do nível dágua e as condições estruturais do barramento. / Among the main building methods of tailings dams, the upstream method is undoubtedly the most vulnerable to the occurrence of the failure originated by the power of seepage groundwater through the embankment. In a reservoir-dam system having low cohesion slimes, such as tailings dams, the power of seepage groundwater benefits the installation of internal erosive processes of piping and liquefaction, the most responsible for the failure already registered. For reduction of failure risks in tailings dams built through upstream method, the assessment of water level behavior must be constant. In this context, the survey presents an instrumental and monitored program composed by piezometer, rainy, downstream outlet, reservoir level of water measures and benchmark providing the increase of safety in these works. The execution of a methodological procedure based on the instrumental and monitored program above mentioned makes possible the assessment of water level behavior in these dams. At last, the relevant aspects for correlation of instrumental data with the limit-values defined for the project are described, meaningful criterion for the success of an instrumental program. The methodological procedure showed efficiency for the obtain of indispensable patterns for a right level of water behavior assessment and structure embankment condictions.

A contaminação da água subterrânea por nitrato em áreas urbanas é um problema muito comum no Brasil. Geralmente muito dos estudos restringem-se em descrever somente os problemas associados às porções mais superficiais dos aquíferos. Mais recentemente, alguns trabalhos têm detectado a presença de nitrato nas partes mais profundas de aquíferos livres no Estado de São Paulo. Então, o principal objetivo desse trabalho foi o de avaliar os impactos potenciais do saneamento urbano no Aquífero Adamantina (livre, de porosidade primária, com 120 m de espessura saturada) na cidade de Urânia, simulando diferentes cenários de usos da terra, usando modelos numéricos de fluxo e transporte, com os softwares MODFLOW e MT3DMS. A cidade de Urania é abastecida por água subterrânea e a rede de esgoto cobre quase a totalidade da área urbana, em um sistema operado pela SABESP (Companhia de Saneamento Básico do Estado de São Paulo). Poços privados e sistemas de saneamento in situ são práticas bastante comuns na cidade. Os resultados da modelagem de fluxo permitiram identificar que o tempo de trânsito das águas subterrâneas entre sua área de recarga e a porção inferior do Aquífero Adamantina (120 m da superfície), sem a operação de poços de produção, é de aproximadamente 60 anos. Este tempo diminui para menos de 40 anos quando estes poços estão bombeando. Caso a contaminação por nitrato seja de uma fonte constante em toda a área urbana, os resultados da modelação mostram que o aquífero tem capacidade de diluir apenas 30% da contaminação inicial. Considerando a construção de uma rede de esgoto totalmente eficiente, o modelo indicou que o tempo de recuperação das porções rasa e intermediária do aquífero é de 10 anos. Já na porção mais profunda, a contaminação perduraria por um período de 90 anos após o encerramento da fonte, com uma fração de 11% de sua concentração inicial, após 10 anos. Assim, conclui-se que a efetividade de estender a rede de esgoto no município em um período de 10 anos é uma medida interessante para mitigação do aquífero frente à contaminação por nitrato. A capacidade máxima de diluição do contaminante pelo aquífero na área urbana de Urânia corresponde a fontes de contaminação de até 100 mg/L de nitrato oriundas de áreas de 65 m x 65 m na zona urbana do município, com um espaçamento de 130 m x 130 m entre elas. A alternativa de contenção da contaminação para porções inferiores do aquífero por meio da existência de poços de produção com seção filtrante inserida na porção rasa do aquífero, visando à utilização desta água bombeada para usos menos nobres, enquanto os poços de produção destinados ao consumo humano, cujos filtros estariam posicionados na porção profunda, permaneceriam protegidos, somente se mostrou interessante quando as concentrações originais de nitrato forem inferior a 56 mg/L, pois, desse modo, a capacidade de diluição do aquífero faria com que a concentração em água da porção profunda fosse inferior ao limite de potabilidade. / Groundwater contamination by nitrate in urban areas is a very common problem in Brazil. Until now, many studies just describe the problem associated to shallowest part of aquifers. More recently, some works have detected the presence of nitrate in the deeper portion of some important unconfined aquifers in Sao Paulo state. Considering this potential problem, the main objective of this work was to evaluate the potential impacts of urban sanitation into the Adamantina Aquifer (primary porosity, unconfined aquifer with 120 m of saturated zone thickness) in the city of Urânia, simulating different land occupation scenarios using flow and transport mathematical models, respectively MODFLOW and MT3DMS codes. The city of Urânia is totally supplied by groundwater and the sewage mains cover almost all the urban area. Both water and sewage mains are operated by the SABESP (State of Sao Paulo water company), but it is necessary to recognize an important number of private wells and also septic tanks and pit latrines operating in the city. The numerical model results could estimate the groundwater transit time from the recharge to the Adamantina Aquifer bottom (120 mbs) in 60 years. When the water wells are pumping, this time is reduced to 40 years. A big impact is expected when the city is not served by any sewage mains and all effluent is infiltrated direct into the soil. In this case, considering a concentration of 100 mg/L, the nitrate will reach the whole aquifer (including its bottom part) with 70% of the original concentration, in 60 years. Taking into the consideration that all domestic effluent is drained by the public sewage mains, the time for recovery is about 10 years for the shallower and intermediate parts of the aquifer. For the deeper part, it takes more than 90 years, but the expected concentration is < 11% of the original one, after 10 years. This permits to conclude that the construction of an efficient public sewage mains network could be a good solution in a time frame of 10 years. It is also possible to define that to dilute a constant load of nitrate of 100 mg/L in an area of 65x65 m, it is necessary to have an area of 130 m x 130 m to keep the water below the Brazilian potable standards.

Seawater intrusion (SWI) is a widespread environmental problem, particularly in arid and semi-arid coastal areas. Unplanned prolonged over-pumping of groundwater is the most important factor in SWI that could result in severe deterioration of groundwater quality. Therefore, appropriate management strategies should be implemented in coastal aquifers to control SWI with acceptable limits of economic and environmental costs. This PhD project presents the development and application of a simulation-optimization (S/O) model to assess different management methods of controlling saltwater intrusion while satisfying water demands, and with acceptable limits of economic and environmental costs, in confined and unconfined coastal aquifers. The first S/O model (FE-GA) is developed by direct linking of an FE simulation model with a multi-objective Genetic Algorithm (GA) to optimize the efficiency of a wide range of SWI management scenarios. However, in this S/O framework, several multiple calls of the simulation model by the population-based optimization model, evaluating best individual candidate solutions resulted in a considerable computational burden. To solve this problem the numerical simulation model is replaced by an Evolutionary Polynomial Regression (EPR)-based surrogate model in the next S/O model (EPR-GA). Through these S/O approaches (FE-GA and EPR-GA) the optimal coordinates and rates of the both abstraction and recharge barriers are determined in the studied management scenarios. As a result, a new combined methodology, so far called ADRTWW, is proposed to control SWI. The ADRTWW model consists of deep Abstraction of saline water near the coast followed by Desalination of the abstracted water to a potable level for public uses and simultaneously Recharging the aquifer using a more economic source of water such as treated wastewater (TWW). In accordance to the available recharge options (injection through well or infiltration from surface pond), the general performance of ADRTWW is evaluated in different hydro-geological settings of the aquifers indicating that it offers the least cost and least salinity in comparison with other scenarios. The great capabilities of both developed S/O models in identification of the best management solutions and the optimal coordinates and rates of the abstraction well and recharge well/pond are discussed. Both FE-GA and EPR-GA can be successfully employed by a robust decision support system. In the next phase of the study, the general impacts of sea level rise (SLR), associated with its transgression nature along the coastline surface on the saltwater intrusion mechanism are investigated in different hypothetical and real case studies of coastal aquifer systems. The results show that the rate and the amount of SWI are considerably greater in aquifers with flat shoreline slopes compared with those with steep slopes. The SWI process is followed by a significant depletion in quantity of freshwater resources at the end of the century. The situation is exacerbated with combined action of SLR and groundwater withdrawals. This finding is also confirmed by 3D simulation of SWI in a regional coastal aquifer (Wadi Ham aquifer) in the UAE subjected to the coupled actions of SLR and pumping.

Surface water and groundwater systems consist of interconnected reservoirs, rivers, and confined and unconfined aquifers. The integrated management of such resources faces several challenges: High dimensionality refers to the requirement of the large number of variables that need to be considered in the description of surface water and groundwater systems. As the number of these variables increases, the computational requirements quickly saturate the capabilities of the existing management methods. Uncertainty relates to the imprecise nature of many system inputs and parameters, including reservoir and tributary inflows, precipitation, evaporation, aquifer parameters (e.g., hydraulic conductivity and storage coefficient), and various boundary and initial conditions. Uncertainty complicates very significantly the development and application of efficient management models. Nonlinearity is intrinsic to some physical processes and also enters through various facility and operational constraints on reservoir storages, releases, and aquifer drawdown and pumping. Nonlinearities compound the previous difficulties. Multiple objectives pertain to the process of optimizing the use of the integrated surface and groundwater resources to meet various water demands, generate sufficient energy, maintain adequate instream flows, and protect the environment and the ecosystems. Multi-objective decision models and processes continue to challenge professional practice. This research draws on several disciplines including groundwater flow modeling, hydrology and water resources systems, uncertainty analysis, estimation theory, stochastic optimization of dynamical systems, and policy assessment. A summary of the research contributions made in this work follows: 1.High dimensionality issues related to groundwater aquifers system have been mitigated by the use of transfer functions and their representation by state space approximations. 2.Aquifer response under uncertainty of inputs and aquifer parameters is addressed by a new statistical procedure that is applicable to regions of relatively few measurements and incorporates management reliability considerations. 3.The conjunctive management problem is formulated in a generally applicable way, taking into consideration all relevant uncertainties and system objectives. This problem is solved via an efficient stochastic optimization method that overcomes dimensionality limitations. 4.The methods developed in this Thesis are applied to the Jordanian water resources system, demonstrating their value for operational planning and management.

In Texas, landowner associations for the management of common-pool resources such as wildlife and groundwater have become increasingly popular. Successful management of white-tailed deer (Odocoileus virginianus) depends upon the collective decision-making of landowners. Likewise, aquifer reserves are a trans-boundary resource subject to the "rule of capture." Numerous factors may affect the success of common-pool associations, including property ownership and habitat characteristics, landowner demographics, and social capital. I used a mail questionnaire to explore the relationship between these factors and their effect on association activities and management practices for eight Wildlife Management Associations (WMAs) occurring within the Lower Post Oak Savannah (LPOS) and the Central Post Oak Savannah (CPOS). In addition, I compared responses of members of WMAs in CPOS to members of the Brazos Valley Water Alliance (BVWA), a groundwater association situated in the region. Compared to CPOS, members of WMAs within the LPOS belonged to much larger groups, were generally more recent landowners that met more often, raised more money using more funding methods, and tended to have longer association membership than CPOS landowners, yet they had lower social capital. CPOS landowners owned significantly more land and considered relaxation/leisure and hunting more important land uses than LPOS landowners. The smaller group size in CPOS may be the most important factor in building social capital. Intra-association trust was positively influenced by the longevity of property ownership, the number of association meetings, the percentage of males in the association, and other factors. Negative influences on trust included absentee ownership and Habitat Cover Index, which was a measure of the amount of wooded habitat present. In CPOS, members of the BVWA were part of a much larger, more heterogeneous, and more recently formed group than members of WMAs. They also placed greater importance on utilitarian aspects of their properties, as opposed to land stewardship for conservation as practiced by members of WMAs. If associations are kept small ( < 50) with more frequent meetings, greater social capital and information sharing may be achieved, which may lead to increased land stewardship practices. However, landowners may be motivated more by their shared values independent of any benefit from their association.

This study aims to determine the safe and sustainable development and management of groundwater resources in Ergene River Basin located in northwestern Turkey. A numerical groundwater model was developed for the Sandy Complex aquifer, which is the most productive and the most widespread aquifer in the basin. The finite difference model with 5900 cells was used to represent the steady and unsteady flow in the aquifer. The model was calibrated in two steps: a steady state calibration by using the observed groundwater levels of January 1970, followed by a transient calibration by using the observed groundwater levels for the period of January 1970 and December 2000. The resulting model was used to develop groundwater pumping scenarios in order to predict the changes in the aquifer system under a set of different pumpage conditions for a planning period of 30 years between January 2001 and December 2030. A total of eight pumping scenarios were developed under transient flow conditions for the planning period and the results were evaluated to determine the safe and sustainable yields of the aquifer. The results, presented in the form of a trade-off curve, demonstrate that the continuation of the present pumping rates exceeds both the safe and the sustainable yields of the aquifer system.

Entre os principais métodos construtivos de barragens de contenção de rejeitos de mineração, o método da linha de montante é sem dúvida o mais vulnerável à ocorrência de acidentes originados por forças de percolação da água pelo barramento. Em um sistema barragem-reservatório constituído de solos finos e de baixa coesão, como as barragens de contenção de rejeitos, as forças de percolação da água favorecem a instalação de processos erosivos internos de piping e liquefação, maiores responsáveis pelos acidentes já registrados. Para redução dos riscos de acidentes em barragens construídas pelo método da linha de montante, a avaliação do comportamento do nível dágua deve ser constante. Neste contexto, o trabalho apresenta um programa de instrumentação e monitoramento composto por medidas piezométricas, pluviométricas, de vazão, do nível dágua do reservatório e de deslocamento horizontal com marco topográfico, com vistas ao aumento do fator de segurança destas obras. A execução de um procedimento metodológico com base no programa de instrumentação e monitoramento acima citado, possibilita a avaliação do comportamento do nível dágua nestas barragens. Por fim, são descritos os aspectos relevantes para correlação dos dados da instrumentação com os valores-limite definidos para o projeto, critério este determinante para o sucesso de um programa de instrumentação. O procedimento metodológico apresentado se mostrou eficiente na obtenção de parâmetros indispensáveis a uma correta avaliação do comportamento do nível dágua e as condições estruturais do barramento. / Among the main building methods of tailings dams, the upstream method is undoubtedly the most vulnerable to the occurrence of the failure originated by the power of seepage groundwater through the embankment. In a reservoir-dam system having low cohesion slimes, such as tailings dams, the power of seepage groundwater benefits the installation of internal erosive processes of piping and liquefaction, the most responsible for the failure already registered. For reduction of failure risks in tailings dams built through upstream method, the assessment of water level behavior must be constant. In this context, the survey presents an instrumental and monitored program composed by piezometer, rainy, downstream outlet, reservoir level of water measures and benchmark providing the increase of safety in these works. The execution of a methodological procedure based on the instrumental and monitored program above mentioned makes possible the assessment of water level behavior in these dams. At last, the relevant aspects for correlation of instrumental data with the limit-values defined for the project are described, meaningful criterion for the success of an instrumental program. The methodological procedure showed efficiency for the obtain of indispensable patterns for a right level of water behavior assessment and structure embankment condictions.

A contaminação da água subterrânea por nitrato em áreas urbanas é um problema muito comum no Brasil. Geralmente muito dos estudos restringem-se em descrever somente os problemas associados às porções mais superficiais dos aquíferos. Mais recentemente, alguns trabalhos têm detectado a presença de nitrato nas partes mais profundas de aquíferos livres no Estado de São Paulo. Então, o principal objetivo desse trabalho foi o de avaliar os impactos potenciais do saneamento urbano no Aquífero Adamantina (livre, de porosidade primária, com 120 m de espessura saturada) na cidade de Urânia, simulando diferentes cenários de usos da terra, usando modelos numéricos de fluxo e transporte, com os softwares MODFLOW e MT3DMS. A cidade de Urania é abastecida por água subterrânea e a rede de esgoto cobre quase a totalidade da área urbana, em um sistema operado pela SABESP (Companhia de Saneamento Básico do Estado de São Paulo). Poços privados e sistemas de saneamento in situ são práticas bastante comuns na cidade. Os resultados da modelagem de fluxo permitiram identificar que o tempo de trânsito das águas subterrâneas entre sua área de recarga e a porção inferior do Aquífero Adamantina (120 m da superfície), sem a operação de poços de produção, é de aproximadamente 60 anos. Este tempo diminui para menos de 40 anos quando estes poços estão bombeando. Caso a contaminação por nitrato seja de uma fonte constante em toda a área urbana, os resultados da modelação mostram que o aquífero tem capacidade de diluir apenas 30% da contaminação inicial. Considerando a construção de uma rede de esgoto totalmente eficiente, o modelo indicou que o tempo de recuperação das porções rasa e intermediária do aquífero é de 10 anos. Já na porção mais profunda, a contaminação perduraria por um período de 90 anos após o encerramento da fonte, com uma fração de 11% de sua concentração inicial, após 10 anos. Assim, conclui-se que a efetividade de estender a rede de esgoto no município em um período de 10 anos é uma medida interessante para mitigação do aquífero frente à contaminação por nitrato. A capacidade máxima de diluição do contaminante pelo aquífero na área urbana de Urânia corresponde a fontes de contaminação de até 100 mg/L de nitrato oriundas de áreas de 65 m x 65 m na zona urbana do município, com um espaçamento de 130 m x 130 m entre elas. A alternativa de contenção da contaminação para porções inferiores do aquífero por meio da existência de poços de produção com seção filtrante inserida na porção rasa do aquífero, visando à utilização desta água bombeada para usos menos nobres, enquanto os poços de produção destinados ao consumo humano, cujos filtros estariam posicionados na porção profunda, permaneceriam protegidos, somente se mostrou interessante quando as concentrações originais de nitrato forem inferior a 56 mg/L, pois, desse modo, a capacidade de diluição do aquífero faria com que a concentração em água da porção profunda fosse inferior ao limite de potabilidade. / Groundwater contamination by nitrate in urban areas is a very common problem in Brazil. Until now, many studies just describe the problem associated to shallowest part of aquifers. More recently, some works have detected the presence of nitrate in the deeper portion of some important unconfined aquifers in Sao Paulo state. Considering this potential problem, the main objective of this work was to evaluate the potential impacts of urban sanitation into the Adamantina Aquifer (primary porosity, unconfined aquifer with 120 m of saturated zone thickness) in the city of Urânia, simulating different land occupation scenarios using flow and transport mathematical models, respectively MODFLOW and MT3DMS codes. The city of Urânia is totally supplied by groundwater and the sewage mains cover almost all the urban area. Both water and sewage mains are operated by the SABESP (State of Sao Paulo water company), but it is necessary to recognize an important number of private wells and also septic tanks and pit latrines operating in the city. The numerical model results could estimate the groundwater transit time from the recharge to the Adamantina Aquifer bottom (120 mbs) in 60 years. When the water wells are pumping, this time is reduced to 40 years. A big impact is expected when the city is not served by any sewage mains and all effluent is infiltrated direct into the soil. In this case, considering a concentration of 100 mg/L, the nitrate will reach the whole aquifer (including its bottom part) with 70% of the original concentration, in 60 years. Taking into the consideration that all domestic effluent is drained by the public sewage mains, the time for recovery is about 10 years for the shallower and intermediate parts of the aquifer. For the deeper part, it takes more than 90 years, but the expected concentration is < 11% of the original one, after 10 years. This permits to conclude that the construction of an efficient public sewage mains network could be a good solution in a time frame of 10 years. It is also possible to define that to dilute a constant load of nitrate of 100 mg/L in an area of 65x65 m, it is necessary to have an area of 130 m x 130 m to keep the water below the Brazilian potable standards.

I takt med att våra städer växer ställs det högre krav på exploateringen av nya områden. Befolkningen i våra städer ökar, detta medför att behovet av bostäder, infrastruktur, skolor och kollektivtrafik med mera ökar. För att tillgodose samhällets krav såväl som skapa attraktiva miljöer finns ett stort intresse i att omvandla tidigare obebodda områden till nya stadsdelar. För att tillgodose vår miljö och natur krävs att samtliga resurser och tillgångar värnas så att nästkommande generation ska kunna bedriva liv på vår planet. De områden som exploateras i dagsläget kan ha komplexa grundläggningsförutsättningar, exempelvis bestå av mark som är förorenad, något som ställer höga krav på grundläggningsarbetet.Denna rapport syftar till att undersöka ifall metoden förhöjd grundläggning är ett alternativ för kommande exploateringar. I rapporten jämförs en traditionell grundläggningsmetod med en förhöjd grundläggningsmetod. Områden som masshantering, grundvattenhantering, samordning samt behovet att stödkonstruktioner avhandlas här då de är centrala i jämförelsen. Ett referensområde söder om Stockholm studeras där komplexa grundläggningsförutsättningar råder som dessutom utgör en bra grund för att göra jämförelsen så verksam som möjligt. Rapporten avhandlar ungefärliga kostnader för grundläggning i de område som studeras ovan, även tillståndsprocesser för hantering av grundvatten samt frågan kring samordning utgör en central del kring de resultat och slutsatser rapporten påvisar.Resultaten visar att kostnadsbesparingar kan göras med metoden förhöjd grundläggning utifrån ett antal givna förutsättningar. De största besparingarna som kan göras är med mindre masshantering samt minskat behov av stödkonstruktioner. Resultatet påvisar en nyanserad bild av konsekvenserna där även negativa aspekter med förhöjd grundläggning lyfts fram. Samordning mellan inblandade aktörer blir än mer relevant då metoden vänder på den traditionella byggnadsordningen. Rapporten ger ett underlag till frågeställningen kring huruvida metoden är tillämpbar eller ej, där rapporten påvisar konkreta för- och nackdelar. / As our cities continue to grow, there is a high demand for exploitation of new areas. Population continue to shift to cities, which means that the need for housing, infrastructure, schools, public transportation, and more is increasing. To meet society's demands and create attractive environments, there is a great interest in transforming previously uninhabited areas into new neighborhoods. To ensure the protection of our environment and nature, all resources and assets must be preserved. The areas being exploited currently may have complex conditions for buildings and may include contaminated land. Which puts high demands on the foundation work.This report aims to investigate whether elevated foundations are an alternative for future developments. The report compares traditional foundation methods with elevated foundation. Areas such as mass management, groundwater management, coordination, and the need for retaining walls are discussed as they are central to the comparison. A reference area south of Stockholm is also discussed, where complex foundation conditions exist. This makes the comparison as effective as possible. The report covers costs as well as the licensing process for groundwater management and the issue of coordination, which are central to the results and conclusions the report presents.The results show that cost savings can be achieved with the elevated foundations under certain conditions. The area where the largest savings can be made is mass management and the reduced need for support structures. The results show a nuanced picture of the consequences, where negative aspects of Elevated Foundation are also highlighted. Coordination among actors involved becomes even more relevant as the method turns the traditional building order upside down. The report provides as advantages and disadvantages a basis for the question of whether the method is applicable or not.

<p>Fresh groundwater quality and availability in coastal areas is affected by seawater intrusion into coastal aquifers, and coastal water quality and ecosystem status may be significantly affected by groundwater pollutants that are transported into coastal waters by submarine groundwater dis-charge (SGD). This thesis uses an overall regional perspective for investigating: i) seawater intru-sion and its possible control in sustainable coastal groundwater management; ii) SGD and its relevant quantification as one interacting part among the diverse main regional pathways of freshwater and tracer/pollutant inputs from land to sea; and iii) the integrated system functioning of both i) and ii) as main components of the same coastal groundwater system.</p><p>Results show that intensive pumping rates may be maintained for a long time before major re-gional seawater intrusion problems are recognized by too high salinities in pumped groundwater. After such late recognition, pumping wells are no longer useful and a common strategy of mov-ing groundwater pumping further upstream from the coast only increases the extent of the salt-water intrusion zone into the aquifer. An alternative strategy may be to control seawater intrusion through artificial groundwater recharge, for instance by sufficiently treated wastewater, which may considerably reduce long-term trends of salinity increase in pumped groundwater, even for small artificial recharge rates compared to pumping rates. In general, account for natural spatial-temporal variability and randomness may be essential for relevant prediction of groundwater dynamics for management purposes. Spatial and temporal randomness effects, however, may not be additive, but rather largely overlapping, with either spatial or temporal randomness being the dominating part that must be accounted for in predictive groundwater dynamics calculations. Aquifer depth is identified as an important control parameter in this context, yielding much greater temporal randomness effects in shallow than in deep aquifers.</p><p>Combined simulation results suggest a simple, approximately linear regional relationship between total SGD and its hydrologically determined freshwater component. Tidal oscillation may signifi-cantly affect such linear dependence of steady-state SGD, but primarily for low SGD conditions. High SGD appears to depend mainly on a dominant freshwater component, which effectively counteracts density-driven flow of seawater into the aquifer and thus decreases also effects of sea-level oscillation on the seawater component of total SGD. Comparative analysis between different SGD estimation methods in different reported high-SGD regions of the world indicates possible anomalously large regional SGD estimation from tracer concentrations in coastal waters, by confusing different main pathways of groundwater flow and pollutant inputs to the sea.</p>