Download or read book Dune Behavior in a Multidirectional Wind Regime written by Anine Oehlenschlaeger Pedersen and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: As with most dune fields, the White Sands Dune Field in New Mexico forms in a wind regime that is not unimodal. In this study, dune behavior at White Sands was documented from a time series of five lidar-derived digital elevation models (DEM) and compared to a record of wind direction and speed during the same period. For the study period of June 2007 - June 2010, 244 sand-transporting wind events occurred and define a dominant wind mode from the SW and lesser modes from the NNW and SSE. Based upon difference maps and tracing of dune brinklines, overall dune behavior consists of migration to the NE, but with along-crest migration of dune sinuosity to the SE. Permutations of the DEMs allow matching specific dune behavior with wind modes. The SW winds are transverse to dune orientations and cause most forward migration. The NNW winds cause along-crest migration of dune sinuosity and low stoss bedforms, as well as SE migration of NE-trending dune terminations. The SSE winds cause ephemeral dune deformation, especially crestal slipface reversals. Dune deformation occurs because of unequal deposition along the lee face as a function of the incidence angle formed between the wind and the local brinkline orientation. Incidence-angle control on dune deformation and types of lee-face surface processes allows for an idealized model for White Sands dunes. The dunes behave as complex systems in which each wind event deforms the dune shape, this new shape then serves as the configuration for the next wind event.

Download or read book Dune Emergence in Multidirectional Wind Regimes written by Cyril Gadal and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aeolian dunes result from the erosion and deposition of sand grains transported by the wind. In turn, the flow adapts to the shape of the sedimentary bed. This coupling between topography, hydrodynamics and transport controls the dune size, orientation and morphology, particularly during the early stage of their growth. In this thesis, we highlight the influence of certain environmental parameters, such as wind regime, sand availability, and dune field boundary conditions on dune emergence. For this, we use a theoretical approach, coupled with laboratory experiments, numerical simulations and field studies.First, we validate the description of dune emergence in areas of high sediment availability as a linear instability. These dunes form as surface waves, whose amplitude increases temporally or spatially, depending on whether they form in the middle of the sedimentary bed, or on its upstream edge. Their orientation, wavelength and spatial/temporal growth rate are then mainly controlled by the angular distribution of sand fluxes.On a non-erodible ground, dunes develop from various sources of sediments (other dunes, river and lakes deposits, etc.). Under specific wind regimes, they elongate to form linear ridges. We show that the spatial organization of these dunes is then controlled by the distribution of sedimentary sources, and not by a length scale intrinsic to the elongation mechanism. Thus, they form periodic dune fields at the downstream edge of sediment beds, or remain isolated structures in zones of localized deposition. In the latter case, they can reach a stable equilibrium state, whose morphology is controlled by the wind reorientation period.Finally, we carry out a large-scale analysis of the Namib Sand Sea based on the theoretical framework of sediment transport and dune morphodynamics, coupled to wind data from climate reanalyses. We then compare field observations with our predictions on sand fluxes and dunes (orientations, morphologies, growth rates). These results allow us to discuss the formation and evolution of sand seas on time scales covering several climatic cycles. More generally, this methodology also makes it possible to infer information on winds or sedimentary material when these are not directly measurable, as well as to gain insight into the evolution and resilience of dune systems subject to climate or anthropogenic changes.

Download or read book The Physics of Blown Sand and Desert Dunes written by R. A. Bagnold and published by Courier Corporation. This book was released on 2012-06-08 with total page 322 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first book to deal exclusively with the behavior of blown sand and related land forms, its accessible style makes it an enduring reference. 84 figures. 16 halftones.

Download or read book Dune Worlds written by Ralph D. Lorenz and published by Springer Science & Business Media. This book was released on 2014-04-22 with total page 311 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book describes how sand dunes work, why they are the way they are in different settings, and how they are being studied. Particular attention is paid to their formation and appearance elsewhere in the solar system. New developments in knowledge about dunes make for an interesting story – like the dunes themselves, dune science is dynamic – and the visual appeal of Aeolian geomorphology ensures that this is an attractive volume. The book is divided into 4 parts, the first of which introduces dunes as a planetary phenomenon, showing a landscape reflecting the balance of geological processes – volcanism, impact, tectonics, erosion, deposition of sediments. Dunes are then considered as emergent dynamical systems: the interaction of sand and wind conspires to generate very characteristic and reproducible shapes. Analogies are given with other emergent structures such as patterned ground before the influence of dunes on desert peoples and infrastructure is studied, together with their use as forensic climatological indicators. Dune Physics is looked at with regard to the mechanics of sand, the physics of wind, saltation – interaction of sand and air – dunes versus ripples and transverse Aeolian ridges, the classification of dune morphology and the sources and sinks of sand. Dune Trafficability considers soil mechanics, effects on mobility on Earth, Mars and elsewhere. In the second part, Earth, Mars, Titan and other moons and planets are examined, beginning with a survey of the major deserts and dunefields on Earth. The authors then turn to Mars and its environment, sediment type, dune stratigraphy, sediment source and sinks and the association of dunes with topographic features. Titan follows - its thick, cold atmosphere, methane dampness, low gravity, morphology – interaction with topography and the implications of dunes for climate and winds. Dunes elsewhere conclude this part. There are few dunefields on Venus, but there is a .possibility of Aeolian transport on Triton and volcanic-related windstreaks on Io.

Download or read book The Geology Ecology and Human History of the San Luis Valley written by Jared Maxwell Beeton and published by University Press of Colorado. This book was released on 2020-08-24 with total page 518 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Geology, Ecology, and Human History of the San Luis Valley explores the rich landscapes and diverse social histories of the San Luis Valley, an impressive mountain valley spanning over 9,000 square miles that crosses the border of south-central Colorado and north-central New Mexico and includes many cultural traditions. Twenty-six expert scholars and educators—including geologists, geographers, biologists, ecologists, linguists, historians, sociologists, and consultants—uncover the natural and cultural history of the region, which serves as home to the Sangre de Cristo Mountains, the San Juan Mountains, Great Sand Dunes National Park and Preserve, and the Rio Grande headwaters. The first section, “The Geology and Ecology of the San Luis Valley,” surveys the geomorphology, hydrology, animal and plant life, conservation, management, and mining of the valley’s varied terrain. The second section, “Human History of the San Luis Valley,” recounts the valley’s human visitation and settlement, from early indigenous life to Spanish exploration to Hispanic and Japanese settlements. This section introduces readers to the region’s wide range of religious identities—Catholic, Latter-day Saint, Buddhist, Jehovah’s Witness, Amish, and Mennonite—and diverse linguistic traditions, including Spanish, English, Dutch, Danish, Japanese, and Mayan. The final section, “Travel Itineraries,” addresses recreation, specifically fly-fishing and rock climbing. The book provides a comprehensive overview of the endemic flora and fauna, human history of indigenous lifeways, and diverse settlement patterns that have shaped the region. The Geology, Ecology, and Human History of the San Luis Valley will appeal to students and scholars of geology, ecology, environmental history, and cultural history, as well as residents and tourists seeking to know more about this fascinating and integral part of Colorado and New Mexico. Contributors: Benjamin Armstrong, Timothy Armstrong, Deacon Aspinwall, Robert Benson, Lorrie Crawford, Kristy Duran, Jeff Elison, Eric Harmon, Devin Jenkins, Bradley G. Johnson, Robert M. Kirkham, Bessie Konishi, Angie Krall, Richard D. Loosbrock, Richard Madole, A. W. Magee, Victoria Martinez, James McCalpin, Mark Mitchell, R. Nathan Pipitone, Andrew Valdez, Rio de la Vista, Damián Vergara Wilson

Download or read book Aeolian Sand and Sand Dunes written by and published by Springer Science & Business Media. This book was released on 2008-11-14 with total page 465 pages. Available in PDF, EPUB and Kindle. Book excerpt: It is more than half a century since the publication of R. A. Bagnold’s classic book The physics of blown sand and desert dunes, and it is a tribute to the quality of Bagnold’s work that many of the fundamental principles which he developed - main valid today. His book continues to be essential reading for any serious s- dent of aeolian processes. However, the past two decades have seen an explosion in the scale of research dealing with aeolian transport processes, sediments, and landforms. Some of this work has been summarized in review papers and edited conference proceedings, but this book provides the rst attempt to review the whole eld of aeolian sand research. Inevitably, it has not been possible to cover all - pects in equal depth, and the balance of included material naturally re ects the - thors’ own interests to a signi cant degree. However, our aim has been to provide as broad a perspective as possible, and to provide an entry point to an extensive mul- disciplinary scienti c literature, some of which has not been given the attention it deserves in earlier textbooks and review papers. Many examples are drawn from existing published work, but the book also makes extensive use of our own research in the Middle East, Australia, Europe, and North America. The book has been written principally for use by advanced undergraduates, po- graduates, and more senior research workers in geomorphology and sedimentology.

Download or read book Migration and Wind Regime of Small Barchan Dunes Within the Algodones Dune Chain Imperial County California written by Roger S. U. Smith and published by . This book was released on 1970 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Aeolian Processes Controlling Dune Morphology Salton Sea California written by Kevin Reilley Mulligan and published by . This book was released on 1997 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Coastal Dunes written by M. L. Martínez and published by Springer Science & Business Media. This book was released on 2007-09-14 with total page 391 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this book, coastal dune specialists from tropical and temperate latitudes cover a wide set of topics, including: geomorphology, community dynamics, ecophysiology, biotic interactions and environmental problems and conservation. The book offers recommendations for future research, identifying relevant topics where detailed knowledge is still lacking. It also identifies management tools that will promote and maintain the rich diversity of the dune environments in the context of continuing coastal development.

Download or read book Sand Dune Systems in Iran Distribution and Activity written by Hamidreza Abbasi and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Aeolian Dune Development and Evolution on a Macro tidal Coast with a Complex Wind Regime Lincolnshire Coast UK written by Anne-Lise Montreuil and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Coastal foredunes are natural aeolian bedforms located landward of the backshore and which interact continuously with the beach. Traditionally, coastal dunes have been associated with onshore winds, however they can be found under more complex wind regimes where offshore winds are common such as the UK East coast, Northern Ireland and New Zealand. This research investigates the ways in which foredune-beach interactions occur under a complex wind regime at a range of overlapping temporal and spatial scales and is innovative in that it explicitly links small-scale processes and morphodynamic behaviour to large scale and long-term dynamics. The study area is the north Lincolnshire coast, East England. Detailed observations of airflow at three locations under varying wind regimes revealed considerable spatial variations in wind velocity and direction, however it was possible to determine a general model of how foredune topography deflected and modified airflow and the resultant geomorphological implications (i.e. erosion and deposition). During direct offshore and onshore winds, airflow remained attached and undeflected; and distinct zones of flow deceleration and acceleration could be identified. During oblique winds airflow was deflected to become more parallel to the dune crest. The field sites used are characterized by a seasonal erosion/accretion cycle and a series of increasingly complex models was developed and tested to determine whether it was possible to predict sand volume changes in the foredune-beach system based on a limited number of variables. The model predictions were tested against detailed digital terrain models at a seasonal timescale. The model prediction that best matched the observed (surveyed) sand volume changes included wind speed, direction, grain size, fetch effect controlled by beach inundation and angle of wind approach was accurate to within ±10% for 18 out of 48 tests at the seasonal scale and 6 out of 12 tests over periods of >5 years. A key variable influencing foredune-beach sand volume is the magnitude and frequency of storm surge events and this was not factored in to the model, but may explain the model-observation mismatch over the medium-term on two occasions. Over the past 120 years historical maps and aerial photographs indicate long-term foredune accretion of approximately 2 m year-1 at the three study sites (1891-2010). At this timescale, rates of coastal foredune accretion reflect the low occurrence of severe storm surges and suggest rapid post-storm recovery. The morphological response of the foredune-beach morphology is considered to be a combination of controlling and forcing factors. Process-responses within the system, associated with nearshore interactions and sediment transfer from the littoral drift, are compiled into a multi-scale morphodynamic model. Important to match appropriate dataset to scale of research question or management plan being explored. In the case of management, long-term records of past activity are necessary to predict the future but also to understand natural responses of system to short-term impact such as storm surge.

Download or read book Modeling of Wind Blown Sand and Desert Dunes written by Gerd Sauermann and published by . This book was released on 2001 with total page 189 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Wind Erosion and Deposition Along a Coastal Sand Dune written by R. J. Lai and published by . This book was released on 1978 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Island Called California written by Elna Bakker and published by Univ of California Press. This book was released on 2023-04-28 with total page 477 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bakker’s classic of ecological science now includes three new chapters on Southern California which make the book more useful than ever. Striking new photographs illustrate the diversity of life, climate, and geological formation. This title is part of UC Press's Voices Revived program, which commemorates University of California Press's mission to seek out and cultivate the brightest minds and give them voice, reach, and impact. Drawing on a backlist dating to 1893, Voices Revived makes high-quality, peer-reviewed scholarship accessible once again using print-on-demand technology. This title was originally published in 1985. Bakker’s classic of ecological science now includes three new chapters on Southern California which make the book more useful than ever. Striking new photographs illustrate the diversity of life, climate, and geological formation. This title is

Download or read book The Physics of Blown Sand and Desert Dunes written by Ralph Alger Bagnold and published by . This book was released on 1941 with total page 165 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Proceedings written by New Zealand Geographical Society. Conference and published by . This book was released on 1999 with total page 840 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Aeolian Dune Dynamics and the Stratigraphic Record written by Sarah Christian Brothers and published by . This book was released on 2016 with total page 478 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dunes and dune fields are dynamic features that respond to the unique boundary conditions under which they evolve by changing migration habits, types and frequencies of interactions, and morphologies. As such, dunes convey information about changing atmospheric and surface conditions on planetary bodies including Earth, Mars, Venus, and Titan, and the stratigraphic record left by these bedforms is used to interpret the evolution of paleoclimate and surface environments. In four parts this work examines how the dynamics of individual dunes, dune fields, and aeolian systems influence stratigraphic architectures across multiple spatial scales. At White Sands Dune Field, New Mexico, the decadal histories of defect and bedform repulsion-type interactions are traced through a time-series of images. The resultant stratigraphic architectures are derived from plan-view exposures and ground penetrating radar sensing of dune interiors. This is the first documentation of the unique stratigraphic architectures that result from interactions between dunes. Within Chasma Boreale, Planum Boreum, Mars, boundary conditions controlling the discrete geomorphic expressions of the Hyperboreae Undae dune fields are evaluated using morphologic distributions. The distributions reveal that dune field expressions change over short horizontal scales and are dependent upon wind regime and sediment state, which operate under the background condition of dune induration by ice. Hyperboreae Undae form only part of the Chasma Boreale sediment system, however. Perennial layered ice deposits also are present on the floor of the reentrant. The changing balance of ice- and sand-dominated processes in space and time have resulted in an accumulation that transitions between ancient aeolian cavi unit-style accumulation and modern layered ice deposit-style accumulation. These accumulations can be interpreted through aeolian sequence stratigraphy. Findings from the Chasma Boreale transitional sediment system are applied to nearby outcrops of a transitional section of ancient cavi unit, which formed in an environment analogous to the modern Chasma Boreale sediment system. A sequence interpretation of the transitional cavi unit stratigraphic succession demonstrates how the aeolian system transitioned into overlying water ice deposits without a gap in the geologic record, verifying that the cavi unit and NPLD should be unified under a sequence stratigraphic framework.