Introduction to modern instrumentation: for hydraulics and environmental sciences

Preface Natural hazards and anthropic activities threaten the quality of the environment surrounding the human being, risking life and health. Among the different actions that must be taken to control the quality of the environment, the gathering of field data is a basic one. In order to obtain the needed data for environmental research, a great variety of new instruments based on electronics is used by professionals and researchers. Sometimes, the potentials and limitations of this new instrumentation remain somewhat unknown to the possible users. In order to better utilize modern instruments it is very important to understand how they work, avoiding misinterpretation of results. All instrument operators must gain proper insight into the working principles of their tools, because this internal view permits them to judge whether the instrument is appropriately selected and adequately functioning. Frequently, manufacturers have a tendency to show the great performances of their products without advising their customers that some characteristics are mutually exclusive. Car manufacturers usually show the maximum velocity that a model can reach and also the minimum fuel consumption. It is obvious for the buyer that both performances are mutually exclusive, but it is not so clear for buyers of measuring instruments. This book attempts to make clear some performances that are not easy to understand to those uninitiated in the utilization of electronic instruments. Technological changes that have occurred in the last few decades are not yet reflected in academic literature and courses; this material is the result of a course prepared with the purpose of reducing this shortage. The content of this book is intended for students of hydrology, hydraulics, oceanography, meteorology and environmental sciences. Most of the new instruments presented in the book are based on electronics, special physics principles and signal processing; therefore, basic concepts on these subjects are introduced in the first chapters (Chapters 1 to 3) with the hope that they serve as a complete, yet easy-to-digest beginning. Because of this review of concepts it is not necessary that the reader have previous information on electronics, electricity or particular physical principles to understand the topics developed later. Those readers with a solid understanding of these subjects could skip these chapters; however they are included because some students could find them as a useful synthesis. Chapter 4 is completely dedicated to the description of transducers and sensors frequently used in environmental sciences. It is described how electrical devices are modified by external parameters in order to become sensors. Also an introduction to oscillators is presented because they are used in most instruments. In the next chapters all the information presented here is recurrently referred to as needed to explain operating principles of instruments. Unauthenticated Download Date | 10/12/14 9:29 PM VIII Preface Chapters 1 to 4 are bitter pills that could discourage readers interested in the description of specific instruments. Perhaps, those readers trying this book from the beginning could abandon it before arriving at the most interesting chapters. Therefore, they could read directly Chapters 5 to 11, going back as they feel that they need the knowledge of the previous chapters. We intended to make clear all the references to the previous subjects needed to understand each one of the issues developed in the later chapters. Chapter 5 contributes to the understanding of modern instrumentation to measure flow in industrial and field conditions. Traditional mechanical meters are avoided to focus the attention on electronic ones, such as vortex, electromagnetic, acoustic, thermal, and Coriolis flowmeters. Special attention is dedicated to acoustic Doppler current profilers and acoustic Doppler velocimeters. Chapter 6 deals with two great subjects; the first is devoted to instruments for measuring dynamic and quasi static levels in liquids, mainly water. Methods to measure waves at sea and in the laboratory are explained, as well as instruments to measure slow changes such as tides or piezometric heads for hydrologic applications. The second subject includes groundwater measurement methods with emphasis on very low velocity flowmeters which measure velocity from inside a single borehole. Most of them are relatively new methods and some are based on operating principles described in the previous chapter. Seepage meters used to measure submarine groundwater discharge are also presented. Chapter 7 presents methods and instruments for measuring rain, wind and solar radiation. Even though the attention is centered on new methods, some traditional methods are described not only because they are still in use, and it is not yet clear if the new technologies will definitely replace them, but also because describing them permits their limitations and drawbacks to be better understood. Methods to measure solar radiation are described from radiation detectors to complete instruments for total radiation and radiation spectrum measurements. Chapter 8 is a long chapter where we have tried to include most remote measuring systems useful for environmental studies. It begins with a technique called DTS (Distributed Temperature Sensing) that has the particularity of being remote, but where the electromagnetic wave propagates inside a fibre optic. The chapter follows with atmosphere wind profilers using acoustic and electromagnetic waves. Radio acoustic sounding systems used to get atmospheric temperature profiles are explained in detail as well as weather radar. Methods for ocean surface currents monitoring are also introduced. The chapter ends with ground penetrating radars. Chapter 9 is an introduction to digital transmission and storage of information. This subject has been reduced to applications where information collected by field instruments has to be conveyed to a central station where it is processed and stored. Some insight into networks of instruments is developed; we think this information will help readers to select which method to use to transport information from field to office, by means of such diverse communication media as fibre optic, digital telephony, Unauthenticated Download Date | 10/12/14 9:29 PM Preface IX GSM (Global System for Mobile communications), satellite communications and private radio frequency links. Chapter 10 is devoted to satellite-based remote sensing. Introductory concepts such as image resolution and instrument?s scanning geometry are developed before describing how passive instruments estimate some meteorological parameters. Active instruments are presented in general, but the on-board data processing is emphasized due to its importance in the quality of the measurements. Hence, concepts like Synthetic Aperture Radar (SAR) and Chirp Radar are developed in detail. Scatterometers, altimeters and Lidar are described as applications of the on-board instruments to environmental sciences. Chapter 11 attempts to transfer some experiences in field measuring to the readers. A pair of case studies is included to encourage students to perform tests on the instruments before using them. In this chapter we try to condense our ideas, most of them already expressed throughout the book, about the attitude a researcher should have with modern instruments before and after a measuring field work. As can be inferred from the foregoing description the book aims to provide students with the necessary tools to adequately select and use instruments for environmental monitoring. Several examples are introduced to advise future professionals and researchers on how to measure properly, so as to make sure that the data recorded by the instruments actually represents the parameters they intend to know. With this purpose, instruments are explained in detail so that their measuring limitations are recognized. Within the entire work it is underlined how spatial and temporal scales, inherent to the instruments, condition the collection of data. Informal language and qualitative explanations are used, but enough mathematical fundamentals are given to allow the reader to reach a good quantitative knowledge. It is clear from the title of the book that it is a basic tool to introduce students to modern instrumentation; it is not intended for formed researchers with specific interests. However, general ideas on some measuring methods and on data acquisition concepts could be useful to them before buying an instrument or selecting a measuring method. Those readers interested in applying some particular method or instrument described in this book should consider these explanations just as an introduction to the subject; they will need to dig deeper in the specific bibliography before putting hands on.Fil: Guaraglia, Dardo Oscar. Universidad Nacional de la Plata. Facultad de Ingeniería. Departamento de Hidraulica. Area Hidraulica Basica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Pousa, Jorge Lorenzo. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Laboratorio de Oceanografía Costera y Estuarios; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentin

Las fluctuaciones del nivel del mar durante el Cuaternario

Los cambios del nivel del mar han ejercido una fuerte influencia en la evolución del planeta y en la historia de la humanidad. En una escala de tiempo geológico, las variaciones de los niveles oceánicos han dejado un registro ampliamente distribuido en la forma de depósitos sedimentarios. El descenso del nivel del mar durante la Ultima Glaciación, que alcanzó unos 120 metros hace 18.000 años, permitió la emergencia del estrecho de Bering y la migración humana desde Eurasia hacia América. Se estima que actualmente reside en áreas costeras un 75% de la población mundial. Investigaciones recientes indican que el nivel medio del mar aumenta entre 1,6 y 1,8 mm/año. El incremento de los gases de invernadero y el calentamiento global resultante han planteado escenarios inquietantes ante una futura aceleración del aumento del nivel del mar, que provocaría impactos significativos en los sistemas costeros y en la población

Las fluctuaciones del nivel del mar durante el Cuaternario

Los cambios del nivel del mar han ejercido una fuerte influencia en la evolución del planeta y en la historia de la humanidad. En una escala de tiempo geológico, las variaciones de los niveles oceánicos han dejado un registro ampliamente distribuido en la forma de depósitos sedimentarios. El descenso del nivel del mar durante la Ultima Glaciación, que alcanzó unos 120 metros hace 18.000 años, permitió la emergencia del estrecho de Bering y la migración humana desde Eurasia hacia América. Se estima que actualmente reside en áreas costeras un 75% de la población mundial. Investigaciones recientes indican que el nivel medio del mar aumenta entre 1,6 y 1,8 mm/año. El incremento de los gases de invernadero y el calentamiento global resultante han planteado escenarios inquietantes ante una futura aceleración del aumento del nivel del mar, que provocaría impactos significativos en los sistemas costeros y en la población.Fundación Museo La Plat

A sedimentary basin as a cradle for biodiversity: the case of the Salado basin in the Buenos Aires province, Argentina

The sedimentary Salado basin is located in the Province of Buenos Aires, Argentina, and extends for about 150,000 km2; of which 50,000 km2 correspond to the lower estuary (or marine estuary) of the Rio de la Plata and to the adjacent sector of the Atlantic Ocean. The basin, which takes its name from the homonymous river that crosses it, is composed of blocks that allowed fluvial-lacunar environments with extended flood plains to be developed. The present configuration of the basin comes from recent sedimentary fill, and shows a broad accretion plain with a low topographic slope that extends with similar features toward the continental shelf. With a sedimentary thickness of over 6,000 m, the Salado basin is characterized by a large vertical development of Upper Paleozoic, Mesozoic and Tertiary continental sediments, with no outcrops from before the Quaternary. The origin of the basin can be related to the development of extensional fractures that took place over ancient weakness zones where the starting aperture mechanism of Gondwana began. The geographical location of the basin, together with its large extent, low elevation over sea level, geology, geomorphology and the prevalent humid climate have produced a particular hydrological behavior with strong ecological characteristics. Vertical water movements (evapotranspiration – infiltration) predominate over horizontal ones (runoff), and there is a strong connection between surface water and groundwater. Due to the low topographic gradients the regional velocity of runoff and streams are very much reduced, which results in a longer time of contact between water and the soil surface and the ensuing increase in infiltration and evapotranspiration. Local and regional seepage are identified. Local seepage refers to an active subsurface flow that outcrops in creeks or ponds, forming their base flow. Regional seepage is a very slow passive flow connected with the deep sedimentary layers in which it takes place. Because of the frequent presence of a shallow water table, surface water and groundwater are strongly related, thus allowing the existence of numerous water bodies rich in biotic resources. The study area has a high biodiversity with sectors of considerable importance for conservation purposes. It can really be considered as a cradle for biodiversity, even though sensitive to human activities. The study area periodically experiences prolonged floods and strong droughts that have frequently led to great losses in the agricultural production and in the urban and road infrastructures. However, floods prevent soil from being salinized, and control the spreading of some harmful dicotyledons in pastures. A general monitoring proposal that would be very useful for the management of natural resources is also given.Facultad de Ciencias Naturales y MuseoFacultad de Ingenierí

Las fluctuaciones del nivel del mar durante el Cuaternario

Los cambios del nivel del mar han ejercido una fuerte influencia en la evolución del planeta y en la historia de la humanidad. En una escala de tiempo geológico, las variaciones de los niveles oceánicos han dejado un registro ampliamente distribuido en la forma de depósitos sedimentarios. El descenso del nivel del mar durante la Ultima Glaciación, que alcanzó unos 120 metros hace 18.000 años, permitió la emergencia del estrecho de Bering y la migración humana desde Eurasia hacia América. Se estima que actualmente reside en áreas costeras un 75% de la población mundial. Investigaciones recientes indican que el nivel medio del mar aumenta entre 1,6 y 1,8 mm/año. El incremento de los gases de invernadero y el calentamiento global resultante han planteado escenarios inquietantes ante una futura aceleración del aumento del nivel del mar, que provocaría impactos significativos en los sistemas costeros y en la población.Fundación Museo La Plat

A sedimentary basin as a cradle for biodiversity: the case of the Salado basin in the Buenos Aires province, Argentina

The sedimentary Salado basin is located in the Province of Buenos Aires, Argentina, and extends for about 150,000 km2; of which 50,000 km2 correspond to the lower estuary (or marine estuary) of the Rio de la Plata and to the adjacent sector of the Atlantic Ocean. The basin, which takes its name from the homonymous river that crosses it, is composed of blocks that allowed fluvial-lacunar environments with extended flood plains to be developed. The present configuration of the basin comes from recent sedimentary fill, and shows a broad accretion plain with a low topographic slope that extends with similar features toward the continental shelf. With a sedimentary thickness of over 6,000 m, the Salado basin is characterized by a large vertical development of Upper Paleozoic, Mesozoic and Tertiary continental sediments, with no outcrops from before the Quaternary. The origin of the basin can be related to the development of extensional fractures that took place over ancient weakness zones where the starting aperture mechanism of Gondwana began. The geographical location of the basin, together with its large extent, low elevation over sea level, geology, geomorphology and the prevalent humid climate have produced a particular hydrological behavior with strong ecological characteristics. Vertical water movements (evapotranspiration – infiltration) predominate over horizontal ones (runoff), and there is a strong connection between surface water and groundwater. Due to the low topographic gradients the regional velocity of runoff and streams are very much reduced, which results in a longer time of contact between water and the soil surface and the ensuing increase in infiltration and evapotranspiration. Local and regional seepage are identified. Local seepage refers to an active subsurface flow that outcrops in creeks or ponds, forming their base flow. Regional seepage is a very slow passive flow connected with the deep sedimentary layers in which it takes place. Because of the frequent presence of a shallow water table, surface water and groundwater are strongly related, thus allowing the existence of numerous water bodies rich in biotic resources. The study area has a high biodiversity with sectors of considerable importance for conservation purposes. It can really be considered as a cradle for biodiversity, even though sensitive to human activities. The study area periodically experiences prolonged floods and strong droughts that have frequently led to great losses in the agricultural production and in the urban and road infrastructures. However, floods prevent soil from being salinized, and control the spreading of some harmful dicotyledons in pastures. A general monitoring proposal that would be very useful for the management of natural resources is also given.Facultad de Ciencias Naturales y MuseoFacultad de Ingenierí

A sedimentary basin as a cradle for biodiversity: the case of the Salado basin in the Buenos Aires province, Argentina

The sedimentary Salado basin is located in the Province of Buenos Aires, Argentina, and extends for about 150,000 km2; of which 50,000 km2 correspond to the lower estuary (or marine estuary) of the Rio de la Plata and to the adjacent sector of the Atlantic Ocean. The basin, which takes its name from the homonymous river that crosses it, is composed of blocks that allowed fluvial-lacunar environments with extended flood plains to be developed. The present configuration of the basin comes from recent sedimentary fill, and shows a broad accretion plain with a low topographic slope that extends with similar features toward the continental shelf. With a sedimentary thickness of over 6,000 m, the Salado basin is characterized by a large vertical development of Upper Paleozoic, Mesozoic and Tertiary continental sediments, with no outcrops from before the Quaternary. The origin of the basin can be related to the development of extensional fractures that took place over ancient weakness zones where the starting aperture mechanism of Gondwana began. The geographical location of the basin, together with its large extent, low elevation over sea level, geology, geomorphology and the prevalent humid climate have produced a particular hydrological behavior with strong ecological characteristics. Vertical water movements (evapotranspiration – infiltration) predominate over horizontal ones (runoff), and there is a strong connection between surface water and groundwater. Due to the low topographic gradients the regional velocity of runoff and streams are very much reduced, which results in a longer time of contact between water and the soil surface and the ensuing increase in infiltration and evapotranspiration. Local and regional seepage are identified. Local seepage refers to an active subsurface flow that outcrops in creeks or ponds, forming their base flow. Regional seepage is a very slow passive flow connected with the deep sedimentary layers in which it takes place. Because of the frequent presence of a shallow water table, surface water and groundwater are strongly related, thus allowing the existence of numerous water bodies rich in biotic resources. The study area has a high biodiversity with sectors of considerable importance for conservation purposes. It can really be considered as a cradle for biodiversity, even though sensitive to human activities. The study area periodically experiences prolonged floods and strong droughts that have frequently led to great losses in the agricultural production and in the urban and road infrastructures. However, floods prevent soil from being salinized, and control the spreading of some harmful dicotyledons in pastures. A general monitoring proposal that would be very useful for the management of natural resources is also given.Facultad de Ciencias Naturales y MuseoFacultad de Ingenierí

Eco-hydrological role of deep aquifers in the Salado sedimentary basin in the Province of Buenos Aires, Argentina

Although not well known, the eco-hydrological functions of deep aquifers (those having no contact with surface hydrological events) play an important role in the hydrological regime because they can affect the type of habitats, the availability of water and nutrients and the salinity of the medium, among other environmental features. This work aims at characterizing the deep Tertiary hydrogeological units of the Salado sedimentary basin in the Province of Buenos Aires, Argentina, at a regional scale, and to determine their environmental importance in the hydrological cycle. The geological characterization of the study area is based on the drilling profiles from oil exploration wells bored by different oil companies between 1948 and 1994, and also from the existing literature. The conclusion is that water exchange between quaternary surface aquifers in contact with atmospheric events and deep tertiary aquifers is one of the main processes that keep the hydrologic balance of the region. Not only is this crucial for the conservation of the numerous and well-developed ecosystems in the basin wetlands, but also significant for the agricultural and cattle-raising activities of the region.Facultad de Ciencias Naturales y Muse

Las nuevas tecnologías para la medición de niveles de agua subterránea

La medición de niveles de aguas subterráneas representa un procedimiento frecuente en hidrogeología. En este trabajo se intenta concientizar acerca de los recaudos que se deberían tener, antes, durante y con posterioridad a la utilización de registradores de niveles con sensores de presión. Se han realizado experiencias bajo distintas condiciones y se han examinado sus resultados. Se utilizan en forma comparativa los datos obtenidos con 5 registradores de presión sometidos a similares variaciones. Se analizan las características de estos registradores y se identifican posibles fuentes de error. Teniendo en cuenta las condiciones de campo en las que se realizan estas mediciones, se describe la influencia de la presión atmosférica en la calidad de los datos, los efectos de los cambios de la temperatura, la estabilidad de la calibración y la recalibración. Se resalta la necesidad de verificación del comportamiento del instrumento, en relación a la aplicación a realizar, y la estimación cuantitativa del error en las mediciones.Groundwater level measurements are a common practice in hydrogeology. This work intends the users to be aware about some matters that should be taken into account before, during and after the use of level loggers with pressure sensors. Experiments have been carried out under different conditions and their outcomes have been analyzed. Data from five pressure sensors subject to similar variations have been used comparatively. The characteristics of these sensors have been examined and possible sources of error have been identified. The influence of atmospheric pressure on data quality, the effect of temperature changes, calibration stability and recalibration are described taking into account the field conditions under which usual measurements are performed. The need for verifying the behavior of the instrument as regards the application to be carried out and the quantitative estimation of error are highlighted.Universidad Nacional de La Plat

Respuesta hidrogeomorfológica al ascenso del nivel del mar en la Bahía de Samborombón (Argentina)

El objetivo de este trabajo es plantear el significado del aumento del nivel del mar en los cambios hidrogeomorfológicos en la Bahía de Samborombón. A partir de información geológica, geomorfológica e hidrológica básica se realizó un análisis morfológico de la planicie costera de la bahía a través de la interpretación de imágenes de satélite y fotografías aéreas obtenidas entre 1972 y 2010. El modelo de elevación digital (DEM) se obtuvo de datos de SRTM (USGS/NAS). El análisis de las condiciones actuales y la evolución reciente han mostrado significativos cambios geomorfológicos (áreas de inundaciones, erosión, depositación de sedimentos) que indican la alta sensibilidad de la región frente a modificaciones en las condiciones hidrológicas. La simulación del ascenso del nivel del mar afecta seriamente las marismas y la llanura de marea, reconociéndose los efectos hacia el interior hasta alrededor de 30 km. A su vez tendrá efectos directos sobre la posición de las aguas subterráneas, con especial referencia a la capa freática. En estas condiciones la franja costera permanecerá cubierta por el agua. Hacia el interior se anegarán en forma permanente los sectores bajos, mientras que gran parte del área restante presentará un alto riesgo de inundación.Facultad de Ciencias Naturales y Muse