Groundwater is one of the main sources for drinking water and agricultural activities. Various activities of both humans and nature may lead to groundwater pollution. Very often, pollution, or contamination, of groundwater goes undetected for long periods of time until it begins to affect human health and/or the environment. Cleanup technologies used to remediate pollution can be costly and remediation processes are often protracted. A more practical and feasible way to manage groundwater contamination is to monitor and predict contamination and act as soon as there is risk to the population and the environment. Predicting groundwater contamination requires advanced numerical models of groundwater flow and solute transport. Such numerical modeling is increasingly becoming a reference criterion for water resources assessment and environmental protection. Subsurface numerical models are, however, subject to many sources of uncertainties from unknown parameters and approximate dynamics. This dissertation considers the sequential data assimilation approach and tackles the groundwater contamination problem at the port of Rotterdam in the Netherlands. Industrial concentration data are used to monitor and predict the fate of organic contaminants using a three dimensional coupled flow and reactive transport model. We propose a number of 5 novel assimilation techniques that address different challenges, including prohibitive computational burden, the nonlinearity and coupling of the subsurface dynamics, and the structural and parametric uncertainties. We also investigate the problem of optimal observational designs to optimize the location and the number of wells. The proposed new methods are based on the ensemble Kalman Filter (EnKF), which provides an efficient numerical solution to the Bayesian filtering problem. The dissertation first investigates in depth the popular joint and dual filtering formulations of the state-parameters estimation problem. New methodologies, algorithmically similar, but more efficient numerically, are then proposed based on a more consistent derivation with the Bayesian filtering approach. To reduce computational cost, I further extend the formulation of the hybrid EnKF-variational approach to the state parameter estimation problem and propose an adaptive scheme for the specification of the weights of the flow-dependent and static background covariance matrices. The new adaptive hybrid scheme is shown to provide much better results than the EnKF while using a fraction of the ensemble size. The new methods are implemented and successfully tested with a realistic coupled subsurface and transport-reaction model of the port of Rotterdam by assimilating industrial data on biodegradable chlorinated hydrocarbons. The observational design problem for placing hydrologic wells is subsequently considered and a new efficient solution is proposed that combines concepts from both information theory and data assimilation

Nonpoint source (NPS) pollution is possibly the greatest form of contamination to our nation's waters. Nutrient pollutants, such as nitrate and ammonium, often enter aquatic ecosystems through surface and subsurface hydrological transport that drain agricultural watersheds. The over-abundance of nitrogen within these watersheds is easily transported to receiving stream and rivers, and result in aquatic ecosystem degradation. In response to the problem of nutrient loading to aquatic ecosystems, ecosystems scientists and federal and state governments have recommended the use of streamside management zones (SMZ) to reduce the amount of NPS pollutants. A small agricultural watershed in southwestern North Carolina was utilized to quantify subsurface transport of nitrate and ammonium to a naturally developing riparian area along Cartoogechaye Creek. Vertical and lateral transport of nitrate and ammonium were measured along three transect perpendicular to the stream. Transects were instrumented with time domain reflectometry (TDR) and porous cup tension lysimeters to monitor soil water and nutrient flux through the pasture and riparian area located at the base of the watershed. The HYDRUS 2-D flow and transport model was used to predict and simulate subsurface flow. Predicted flow was coupled with observed field nutrient data to quantify nutrient flux as a function of slope location. HYDRUS 2-D was capable of simulating subsurface flow (saturated and unsaturated) as a function of observed soil physical properties (bulk density, saturated hydraulic conductivity, particle size distribution, water retention characteristics) and climatic data (precipitation, air temperature, wind speed, etc.). The riparian area was effective in reducing the amount of nonpoint source pollution to a naturally developing riparian area from an agricultural watershed. Dramatic decreases in both NO3- -N and NH4+ -N in upland pasture water were observed within the riparian area. Seasonal percent reductions of NO3- from the pasture to riparian area in subsurface water within the study watershed are as follows: summer (2002) = 456%; fall (2002) = 116%; winter (2003) = 29%; spring = 9%, pasture and riparian, respectively. / Master of Science

Near-level Prairie landscapes have received limited attention in hydrological research. For this thesis, hydrometric measurements and four tracing experiments were completed at three “riparian-to-stream” sites in the Catfish Creek Watershed (southeastern Manitoba) to enhance Prairie hydrology understanding. First, hydrologic state variables were examined to infer vertical and lateral water movement. Second, tracer data were analyzed to evaluate the relative importance of surface versus subsurface water movement. Results show that hydrologic state variables can be useful for inferring riparian-to-stream water movement. Tracer data also revealed that subsurface water movement can contribute significantly to streamflow during snowmelt- and rainfall-triggered events in the study watershed. This thesis demonstrated that subsurface flow is a significant runoff generation mechanism in Prairie landscapes, thus challenging surface water-focused conceptualizations and management strategies that are traditionally used. The findings summarized in this thesis will be critical to improve the performance of hydrological models when applied to the Prairies. / February 2017

A disparidade entre o crescimento populacional e a oferta de água potável apresenta grandes riscos de abastecimento em grandes centros urbanos. A utilização desse recurso em residências é diferenciada em uso potável e não potável. A utilização de água potável para finalidades menos nobres leva à escassez hídrica local em menor prazo, necessitando de busca de água cada vez mais longe, encarecendo o valor desse bem aos usuários. O uso não potável deveria ser suprido por fontes alternativas, como águas pluviais ou água de reúso. Em residências, muitas vezes o volume de água não potável é suprido pela produção de água cinza, necessitando de tratamento para que seu uso não ofereça riscos aos usuários. Sistemas de tratamento tipo wetlands podem ser uma alternativa economicamente viável em locais com disponibilidade de área, tendo como atrativos a independência de energia elétrica para o processo, ausência da necessidade de produtos químicos e forte apelo estético e ambiental. O presente trabalho visou avaliar a viabilidade técnica de sistemas tipo wetlands no tratamento de água cinza, determinando a remoção de material orgânico, a constante de remoção desse substrato, determinar as taxas de remoções de nitrogênio e fósforo e avaliar a eficiência na remoção de indicadores de contaminação fecal em um sistema tipo wetlands de fluxo subsuperficial horizontal cultivado em policultura. O sistema tipo wetlands apresentou remoção média de matéria orgânica próxima a 60% nos para os parâmetros DBO, DQO e COT, possibilitando: K20 DBO = 0,40; K20 DQO = 0,34; e K20 COT 0,30. As taxas de remoção de nutriente foram: 0,07g/m².d de fósforo total e 0,22g/m².d de nitrogênio kjeldahl total. A remoção média de indicadores de contaminação fecal foi de 56% para coliformes totais e uma média de 2,7x104 UFC/100mL e 94% para Escherichia coli com média de 4,6x101 UFC/100mL no efluente final. O efluente final do sistema tipo wetlands apresenta melhora na sua qualidade. / The disparity between population growth and supply of drinking water presents major risks to supply in large urban centers. The use of this feature in homes is different in non-potable and potable use. The use of drinking water for less noble purposes leads to local water shortages in less time, requiring the search of water each time further, the value of this expensive and users. The non-potable use should be supplied by alternative sources such as rainwater or water reuse. In homes, many times the volume of non-potable water is supplied by production of greywater, requiring treatment for their use does not offer risks to users. Systems of treatment like \"wetlands\" may be an economically viable alternative in locations where the availability of area, with attractions such as the independence of electric energy to the process, no need for chemicals and strong aesthetic appeal and environmental. This study aimed to evaluate the technical feasibility of such systems \"wetlands\" in the treatment of gray water, determining the removal of organic material, the constant removal of the substrate, determining the rates of removal of nitrogen and phosphorus and evaluate the efficiency in the removal of indicators of fecal contamination in a system like \"wetlands\" of horizontal subsurface flow grown in polyculture. The system type \"wetlands\" showed average removal of organic matter close to 60% in for the parameters BOD, COD and TOC, allowing: DBO K20 = 0.40; K20 DQO = 0.34 and K20 TOC 0.30. The rates of removal of nutrients were: 0.07 g / m².d of total phosphorus, and 0.22 g / m².d of total Kjeldahl nitrogen. The average removal of indicators of fecal contamination was 56% for total coliforms and an average of 2.7x104CFU/100mL and 94% for Escherichia coli with an average of 4.6x101CFU/100mL in the final effluent. The effluent end of the system as \"wetlands\" has improved its quality.

A disparidade entre o crescimento populacional e a oferta de água potável apresenta grandes riscos de abastecimento em grandes centros urbanos. A utilização desse recurso em residências é diferenciada em uso potável e não potável. A utilização de água potável para finalidades menos nobres leva à escassez hídrica local em menor prazo, necessitando de busca de água cada vez mais longe, encarecendo o valor desse bem aos usuários. O uso não potável deveria ser suprido por fontes alternativas, como águas pluviais ou água de reúso. Em residências, muitas vezes o volume de água não potável é suprido pela produção de água cinza, necessitando de tratamento para que seu uso não ofereça riscos aos usuários. Sistemas de tratamento tipo wetlands podem ser uma alternativa economicamente viável em locais com disponibilidade de área, tendo como atrativos a independência de energia elétrica para o processo, ausência da necessidade de produtos químicos e forte apelo estético e ambiental. O presente trabalho visou avaliar a viabilidade técnica de sistemas tipo wetlands no tratamento de água cinza, determinando a remoção de material orgânico, a constante de remoção desse substrato, determinar as taxas de remoções de nitrogênio e fósforo e avaliar a eficiência na remoção de indicadores de contaminação fecal em um sistema tipo wetlands de fluxo subsuperficial horizontal cultivado em policultura. O sistema tipo wetlands apresentou remoção média de matéria orgânica próxima a 60% nos para os parâmetros DBO, DQO e COT, possibilitando: K20 DBO = 0,40; K20 DQO = 0,34; e K20 COT 0,30. As taxas de remoção de nutriente foram: 0,07g/m².d de fósforo total e 0,22g/m².d de nitrogênio kjeldahl total. A remoção média de indicadores de contaminação fecal foi de 56% para coliformes totais e uma média de 2,7x104 UFC/100mL e 94% para Escherichia coli com média de 4,6x101 UFC/100mL no efluente final. O efluente final do sistema tipo wetlands apresenta melhora na sua qualidade. / The disparity between population growth and supply of drinking water presents major risks to supply in large urban centers. The use of this feature in homes is different in non-potable and potable use. The use of drinking water for less noble purposes leads to local water shortages in less time, requiring the search of water each time further, the value of this expensive and users. The non-potable use should be supplied by alternative sources such as rainwater or water reuse. In homes, many times the volume of non-potable water is supplied by production of greywater, requiring treatment for their use does not offer risks to users. Systems of treatment like \"wetlands\" may be an economically viable alternative in locations where the availability of area, with attractions such as the independence of electric energy to the process, no need for chemicals and strong aesthetic appeal and environmental. This study aimed to evaluate the technical feasibility of such systems \"wetlands\" in the treatment of gray water, determining the removal of organic material, the constant removal of the substrate, determining the rates of removal of nitrogen and phosphorus and evaluate the efficiency in the removal of indicators of fecal contamination in a system like \"wetlands\" of horizontal subsurface flow grown in polyculture. The system type \"wetlands\" showed average removal of organic matter close to 60% in for the parameters BOD, COD and TOC, allowing: DBO K20 = 0.40; K20 DQO = 0.34 and K20 TOC 0.30. The rates of removal of nutrients were: 0.07 g / m².d of total phosphorus, and 0.22 g / m².d of total Kjeldahl nitrogen. The average removal of indicators of fecal contamination was 56% for total coliforms and an average of 2.7x104CFU/100mL and 94% for Escherichia coli with an average of 4.6x101CFU/100mL in the final effluent. The effluent end of the system as \"wetlands\" has improved its quality.

Streamflow dynamics in mountainous environments are controlled by runoff generation processes in the basin upstream. Runoff generation processes are thus a major control of the terrestrial part of the water cycle, influencing both, water quality and water quantity as well as their dynamics. The understanding of these processes becomes especially important for the prediction of floods, erosion, and dangerous mass movements, in particular as hydrological systems often show threshold behavior. In case of extensive environmental changes, be it in climate or in landuse, the understanding of runoff generation processes will allow us to better anticipate the consequences and can thus lead to a more responsible management of resources as well as risks. In this study the runoff generation processes in a small undisturbed catchment in the Chilean Andes were investigated. The research area is characterized by steep hillslopes, volcanic ash soils, undisturbed old growth forest and high rainfall amounts. The investigation of runoff generation processes in this data scarce area is of special interest as a) little is known on the hydrological functioning of the young volcanic ash soils, which are characterized by extremely high porosities and hydraulic conductivities, b) no process studies have been carried out in this area at either slope or catchment scale, and c) understanding the hydrological processes in undisturbed catchments will provide a basis to improve our understanding of disturbed systems, the shift in processes that followed the disturbance and maybe also future process evolution necessary for the achievement of a new steady state. The here studied catchment has thus the potential to serve as a reference catchment for future investigations. As no long term data of rainfall and runoff exists, it was necessary to replace long time series of data with a multitude of experimental methods, using the so called "multi-method approach". These methods cover as many aspects of runoff generation as possible and include not only the measurement of time series such as discharge, rainfall, soil water dynamics and groundwater dynamics, but also various short term measurements and experiments such as determination of throughfall amounts and variability, water chemistry, soil physical parameters, soil mineralogy, geo-electrical soundings and tracer techniques. Assembling the results like pieces of a puzzle produces a maybe not complete but nevertheless useful picture of the dynamic ensemble of runoff generation processes in this catchment. The employed methods were then evaluated for their usefulness vs. expenditures (labour and financial costs). Finally, the hypotheses - the perceptual model of runoff generation generated from the experimental findings - were tested with the physically based model Catflow. Additionally the process-based model Wasim-ETH was used to investigate the influence of landuse on runoff generation at the catchment scale. An initial assessment of hydrologic response of the catchment was achieved with a linear statistical model for the prediction of event runoff coefficients. The parameters identified as best predictors give a first indication of important processes. Various results acquired with the "multi-method approach" show that response to rainfall is generally fast. Preferential vertical flow is of major importance and is reinforced by hydrophobicity during the summer months. Rapid lateral water transport is necessary to produce the fast response signal, however, while lateral subsurface flow was observed at several soil moisture profiles, the location and type of structures causing fast lateral flow on the hillslope scale is still not clear and needs to be investigated in more detail. Surface runoff has not been observed and is unlikely due to the high hydraulic conductivities of the volcanic ash soils. Additionally, a large subsurface storage retains most of the incident rainfall amount during events (>90%, often even >95%) and produces streamflow even after several weeks of drought. Several findings suggest a shift in processes from summer to winter causing changes in flow patterns, changes in response of stream chemistry to rainfall events and also in groundwater-surface water interactions. The results of the modelling study confirm the importance of rapid and preferential flow processes. However, due to the limited knowledge on subsurface structures the model still does not fully capture runoff response. Investigating the importance of landuse on runoff generation showed that while peak runoff generally increased with deforested area, the location of these areas also had an effect. Overall, the "multi-method approach" of replacing long time series with a multitude of experimental methods was successful in the identification of dominant hydrological processes and thus proved its applicability for data scarce catchments under the constraint of limited resources. / Die Abflussdynamik in Mittel- und Hochgebirgen wird durch die Abflussbildungsprozesse im Einzugsgebiet bestimmt. Diese Prozesse kontrollieren damit zu großen Teilen den terrestrischen Teil des Wasserkreislaufs und beeinflussen sowohl Wasserqualität als auch -quantität. Das Verständnis von Abflussbildungsprozessen ist besonders wichtig für die Vorhersage von Hochwasser, Erosion und Massenbewegungen (z.B. Erdrutsche) da hydrologische Systeme oft Schwellenwertverhalten aufweisen. Im Falle weit reichender Umweltveränderungen, wie z.B. Klima- oder Landnutzungsänderungen kann das Verständnis der Abflussbildungsprozesse ein verantwortungsvolleres Management sowohl der Ressourcen als auch der Risiken ermöglichen. In dieser Studie wurden die Abflussbildungsprozesse in einem kleinen, anthropogen unbeeinflussten Einzugsgebiet in den Chilenischen Anden untersucht. Das Untersuchungsgebiet ist durch steile Hänge, vulkanische Ascheböden, ungestörten Naturwald und hohe Niederschlagsmengen charakterisiert. Die Erforschung von Abflussbildungsprozessen ist hier von besonderem Interesse, da a) wenig über das hydrologische Verhalten der hochporösen und hochleitfähigen jungen Ascheböden bekannt ist, b) in dieser Region bisher keine Studien auf Hang- oder Einzugsgebietsskala durchgeführt wurden, und c) das Prozessverständnis in ungestörten Einzugsgebieten als Basis zum besseren Verständnis bereits anthropogen beeinflusster Gebiete dienen kann. Das hier untersuchte Gebiet hat daher das Potential zum Referenzgebiet für zukünftige Studien und Forschungsprojekte. Bedingt durch die Kürze der vorliegenden Abfluss- und Niederschlagszeitreihen war es nötig, den bestehenden Datenmangel durch eine Vielzahl von experimentellen Methoden und Ansätzen auszugleichen. Dieser Ansatz wird im Folgenden der "Multi-Methoden-Ansatz" genannt. Die ausgewählten Methoden sollten dabei so viele Aspekte der Abflussbildung abdecken wie möglich. Es wurden daher nicht nur Zeitreihen von Abfluss, Niederschlag, Bodenfeuchte- und Grundwasserdynamik gemessen, sondern auch eine große Zahl an Kurzzeitmessungen und Experimenten durchgeführt. Diese beinhalteten u.a. Messung des Bestandesniederschlags, Bestimmung der Wasserchemie, Bestimmung bodenphysikalischer Parameter und der Bodenmineralogie, sowie geophysikalische Messungen und Tracermethoden. Die Synthese der Resultate gleicht dem Zusammensetzen eines Puzzles. Das so entstandene Bild des dynamischen Prozess-Ensembles ist trotz möglicher fehlender Puzzlestücke hochinformativ. In einem nächsten Schritt wurden die ausgewählten Methoden im Hinblick auf Erkenntnisgewinn und Kosten (d.h. finanzielle Kosten und Arbeitszeit) evaluiert. Das durch die experimentellen Ergebnisse gewonnene Bild der Abflussbildung wurde anschließend mit Hilfe des physikalisch basierten Modells Catflow überprüft. Weiterhin wurde mit dem prozessbasierten Modell Wasim-ETH der Einfluss der Landnutzung auf die Abflussbildung auf Einzugsgebietsskala untersucht. Die Ergebnisse des "Multi-Methoden-Ansatzes" zeigen, dass die Abflussreaktion in diesem Gebiet sehr schnell erfolgt. Vertikales präferenzielles Fliessen ist hier von großer Bedeutung und wird in den Sommermonaten noch durch Hydrophobizitätseffekte verstärkt. Schneller lateraler Fluss im Untergrund ist eine weitere Vorraussetzung für die schnelle Reaktion des Abflusses (Oberflächenabfluss ist hier aufgrund der hohen hydraulischen Leitfähigkeiten unwahrscheinlich). Obwohl bei der Untersuchung der Bodenfeuchtedynamik in einigen Profilen laterale Fließmuster beobachtet wurden, ist die Art und Lage der Untergrundstrukturen, die auf der Hangskala schnellen lateralen Fluss verursachen, noch unklar und sollte genauer untersucht werden. Die Tatsache, dass bei Niederschlagsereignissen der Großteil der Niederschlagsmenge nicht zum Abfluss kommt (>90%, oft auch >95%), sowie der kontinuierliche Abfluss selbst nach Wochen der Trockenheit, lassen auf einen großen unterirdischen Speicher schließen. Der Wechsel von Winter (nass) zu Sommer (trocken) scheint Veränderungen im Prozess-Ensemble hervorzurufen, die sich in der Änderung von Fließmustern, von Grundwasser-Oberflächenwasser-Interaktionen, sowie veränderter Reaktion der Wasserchemie auf Niederschlagsereignisse beobachten ließ. Die Modellstudie bestätigte die Bedeutung der schnellen Fließwege. Als Folge von Informationsdefiziten über die Strukturen des Untergrunds ließ sich jedoch die Abflussbildung noch nicht vollständig reproduzieren. Die Untersuchung zur Bedeutung der Landnutzung für die Abflussbildung mit Hilfe eines Einzugsgebietsmodells zeigte die Zunahme der maximalen Abflüsse mit zunehmender Entwaldung. Weiterhin erwies sich auch die Lage der abgeholzten Flächen als ein wichtiger Faktor für die Abflussreaktion. Der "Multi-Methoden-Ansatz" lieferte wichtige Erkenntnisse zum Verständnis der Abflussbildungspozesse in den Anden Südchiles und zeigte sich als adäquates Mittel für hydrologische Prozess-Studien in datenarmen Gebieten.

Subsurface flow phenomena characterize many important societal issues in energy and the environment. A key feature of these problems is that subsurface properties are uncertain, due to the sparsity of direct observations of the subsurface. The Bayesian formulation of this inverse problem provides a systematic framework for inferring uncertainty in the properties given uncertainties in the data, the forward model, and prior knowledge of the properties. We address the problem: given noisy measurements of the head, the pdf describing the noise, prior information in the form of a pdf of the hydraulic conductivity, and a groundwater flow model relating the head to the hydraulic conductivity, find the posterior probability density function (pdf) of the parameters describing the hydraulic conductivity field. Unfortunately, conventional sampling of this pdf to compute statistical moments is intractable for problems governed by large-scale forward models and high-dimensional parameter spaces. We construct a Gaussian process surrogate of the posterior pdf based on Bayesian interpolation between a set of "training" points. We employ a greedy algorithm to find the training points by solving a sequence of optimization problems where each new training point is placed at the maximizer of the error in the approximation. Scalable Newton optimization methods solve this "optimal" training point problem. We tailor the Gaussian process surrogate to the curvature of the underlying posterior pdf according to the Hessian of the log posterior at a subset of training points, made computationally tractable by a low-rank approximation of the data misfit Hessian. A Gaussian mixture approximation of the posterior is extracted from the Gaussian process surrogate, and used as a proposal in a Markov chain Monte Carlo method for sampling both the surrogate as well as the true posterior. The Gaussian process surrogate is used as a first stage approximation in a two-stage delayed acceptance MCMC method. We provide evidence for the viability of the low-rank approximation of the Hessian through numerical experiments on a large scale atmospheric contaminant transport problem and analysis of an infinite dimensional model problem. We provide similar results for our groundwater problem. We then present results from the proposed MCMC algorithms. / text

This study is part of a project that was conducted by Florida International University (FIU), which designed, built, and characterized a constructed wetland (CW) wastewater treatment system in El Salvador, Central America. This study focuses on the detailed performance of a field-scale CW in the tropics, consisting of a subsurface flow wetland (SSF) and a surface flow wetland (SF). The SSF had a total area of 151.2 sq. m., filled with gravel and planted with Phragmites, Thalia, and Brachiaria, along three independent cells operating with a flow in parallel and receiving the influent domestic wastewater from a facultative lagoon and preceded the SF. The SF was a shallow open basin containing alternating regions of open water (195 sq. m. total) with submerged aquatic plants (Elodea) and regions of shallower water (605 sq. m. total) filled with emergent wetland vegetation (Typha, Thalia, and Cyperus). The design, construction, startup and operation phases of the field scale CW in that tropical setting are thus described with detail, including both SSF and SF characterization of influent and effluents. The SSF average hydraulic detention times during the wet and dry season were 2 days ± 0.9 days and 4 days ± 0.4 days, respectively; and the SF average hydraulic detention times during the wet and dry season were 20 days ± 11.1 days and 77 days ± 19.5 days, respectively. Brachiaria/Cyperus presented better results during the wet season with average BOD5 residuals of 36% ± 25%, and Thalia/Thalia during the dry season with average BOD5 residuals of 33% ± 22%. Phragmites/Typha presented better results during both seasons with average TSS residuals of 2% ± 3% (wet season), and 2% ± 2% (dry season). Residuals are also presented for COD, Oil & Grease, Total Fecal Coliform, Total Phosphorus, and Total Nitrogen. In addition, an assessment of the empirical models used in the design of the system is completed, having the EPA methodology as the preferred for BOD5 removal and three methodologies for TSS removal under tropical climate conditions. A comparison of the differences in treatment associated with each one of the selected plants and their combinations is also discussed. In summary, results strongly suggest that the CW system can effectively reduce contaminants in wastewater to levels that are comparable with the objective levels (i.e., secondary treatment levels).

Preferential flow paths are areas of substantially higher permeability than surrounding media. Macropores and soil pipes are a type of preferential flow path where conduit-like voids in the subsurface are typically greater than three millimeters in diameter. They are known to occur in agricultural and forest soils, often as a result of biological and physical processes. Macropores also exist in stream banks and have the potential to enhance the exchange of water and solutes between the channel and riparian groundwater, yet the geographic distribution of bank macropores is unknown. Here we determined the abundance, distribution, and geometry of naturally occurring surface-connected macropores in the banks of 20 streams across five physiographic provinces in the Eastern United States. We identified a total of 1,748 macropores, which were present in all 20 streams, with 3.8 cm average width, 3.3 cm average height, 11.5 cm average depth, and 27.9 cm average height above water surface elevation. Macropore abundance, distribution and geometry were statistically different between physiographic provinces, stream orders, and soil textures, with the latter being the most important. Macropores tended to be larger and more abundant in soils with a high cohesiveness and a low hydraulic conductivity compared to soils with a low cohesiveness and high hydraulic conductivity. As a result, streams with greater longitudinal heterogeneity of soil texture also had greater heterogeneity of macropore density. However, macropore size and height above baseflow water surface elevation also increased with stream order and therefore stream size. This work represents the first attempt to characterize macropores across a variety of riverine systems and presents evidence that macropores may play an important role in hyporheic exchange within stream banks. These results may have water quality implications, where macropores may enhance hyporheic exchange yet reduce the filtering capacity of riparian buffer zones. / MS

<p>This report deals with the performance of a batch flow treatment of landfillleachate compared with a continuous flow system. The parameters in focus were total Kjeldahl nitrogen (TKN), BOD5 and COD. The pilot-scale experiment used eight barrels with a volume of 150 liters. Each barrel was constructed differently concerning its flow, its bed material grain size and its presence of plants or not. Four of the barrels worked in batch mode, thus four in continuous flow mode. The continuous flow systems were provided with water trough small tubes with regulators. Samples were collected once a week and analysis was carried out yielding results of BOD5, COD, TKN, pH and conductivity of the effluents. The same parameters were analyzed for the influent every week. The result shows that a wetland is a good way of treating the landfill leachate as the BOD5, COD and TKN decreases. Moreover the color, which contravenes with legislative demands in the region, was distinctly decreased. Yet the report failed to show a significant difference between batch loaded and continuous flow wetlands. More studies have to be carried out in order to determine or contradict whether batch mode in fact provides a better treatment.</p>