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 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 Geomorphology of Desert Dunes written by Nicholas Lancaster and published by Cambridge University Press. This book was released on 2023-02-28 with total page 349 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sand dunes are a globally important depositional landform and sedimentary system. Their origins and dynamics are important in understanding how deserts have evolved in response to climate change and changes in sand supply and mobility, and how they will continue to evolve in the future. This book provides a state-of-the-art review of the characteristics of desert dunes and their sediments, and explores their dynamics on timescales from days to millennia as they respond to changes in wind speed and direction, precipitation and sand supply. This extensively revised edition reflects the advances in our understanding of desert dunes, their dynamics and history; and covers recent developments including the luminescence dating revolution, ground penetrating radar and advances in numerical modeling. Also covering dunes on Mars and Titan, this authoritative reference is a must-have for researchers and graduate students working on desert dunes and aeolian geomorphology.
Download or read book Encyclopedia of Geomorphology written by Andrew Goudie and published by Routledge. This book was released on 2013-04-15 with total page 1190 pages. Available in PDF, EPUB and Kindle. Book excerpt: Volume editor is the leading authority in the field Alphabetically organized in two volumes c.700 comprehensively signed, cross-referenced and indexed entries Detailed bibliographies and suggestions for further reading follow most entries Fully illustrated: over 300 plates and line drawings Written by an editorial team of over 270 experts from over thirty countries
Download or read book Earth Environments written by David Huddart and published by John Wiley & Sons. This book was released on 2020-01-07 with total page 1006 pages. Available in PDF, EPUB and Kindle. Book excerpt: Comprehensive coverage of the whole Earth system throughout its entire existence and beyond Complete with a new introduction by the authors, this updated edition helps provide an understanding of the past, present, and future processes that occur on and in our Earth—the fascinating, yet potentially lethal, set of atmospheric, surface, and internal processes that interact to produce our living environment. It introduces students to our planet’s four key interdependent systems: the atmosphere, lithosphere, hydrosphere and biosphere, focusing on their key components, the interactions between them, and environmental change. The book also uses geological case studies throughout, in addition to the modern processes. Topics covered in the Second Edition of Earth Environments: Past, Present and Future include: an Earth systems model; components systems and processes; atmospheric systems; oceanography; surface and internal geological systems; biogeography; and aspects of Earth's record. The book also discusses the impact of climate and environmental change in a final chapter that draws together Earth's systems and their evolution, and looks ahead to potential future changes in Earth’s environments. Updated to include all the major developments since 2008 Features research boxes containing summaries based on recent key journal articles Includes a companion web site containing multiple choice revision quizzes for students, PowerPoint slides for lecturers, useful links, and more Presents further reading for each topic so that students can build their knowledge base to underpin their own undergraduate research project/dissertation Offers additional case studies in each chapter for enhanced reader understanding Earth Environments: Past, Present and Future is an excellent text for undergraduates in geosciences, environmental science, physical geography, natural hazards, and ecology.
Download or read book Terrigenous Clastic Depositional Systems written by William E. Galloway and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 505 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nonrenewable energy resources, comprising fossil fuels and uranium, are not ran domly distributed within the Earth's crust. They formed in response to a complex array of geologic controls, notably the genesis of the sedimentary rocks that host most commercial energy resources. It is this genetic relationship between economic re sources and environment that forms the basis for this book. Our grouping of petro leum, coal, uranium, and ground water may appear to be incongruous or artificial. But our basic premise is that these ostensibly disparate resources share common genetic attributes and that the sedimentological principles governing their natural distributions and influencing their recovery are fundamentally similar. Our combined careers have focused on these four resources, and our experiences in projects worldwide reveal that certain recurring geologic factors are important in controlling the distribution of com mercial accumulations and subsurface fluid flow. These critical factors include the shape and stability of the receiving basin, the major depositional elements and their internal detail, and the modifications during burial that are brought about in these sediments by pressure, circulating fluids, heating, and chemical reaction. Since the first edition of this book in 1983, there has been a quantum leap in the volume of literature devoted to genetic stratigraphy and refinement of sedimentologi cal principles and a commensurate increase in the application of these concepts to resource exploration and development.
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 Encyclopedia of Geography written by Barney Warf and published by SAGE Publications. This book was released on 2010-09-21 with total page 3543 pages. Available in PDF, EPUB and Kindle. Book excerpt: Simply stated, geography studies the locations of things and the explanations that underlie spatial distributions. Profound forces at work throughout the world have made geographical knowledge increasingly important for understanding numerous human dilemmas and our capacities to address them. With more than 1,200 entries, the Encyclopedia of Geography reflects how the growth of geography has propelled a demand for intermediaries between the abstract language of academia and the ordinary language of everyday life. The six volumes of this encyclopedia encapsulate a diverse array of topics to offer a comprehensive and useful summary of the state of the discipline in the early 21st century. Key Features Gives a concise historical sketch of geography′s long, rich, and fascinating history, including human geography, physical geography, and GIS Provides succinct summaries of trends such as globalization, environmental destruction, new geospatial technologies, and cyberspace Decomposes geography into the six broad subject areas: physical geography; human geography; nature and society; methods, models, and GIS; history of geography; and geographer biographies, geographic organizations, and important social movements Provides hundreds of color illustrations and images that lend depth and realism to the text Includes a special map section Key Themes Physical Geography Human Geography Nature and Society Methods, Models, and GIS People, Organizations, and Movements History of Geography This encyclopedia strategically reflects the enormous diversity of the discipline, the multiple meanings of space itself, and the diverse views of geographers. It brings together the diversity of geographical knowledge, making it an invaluable resource for any academic library.
Download or read book Geomorphology of Desert Environments written by Anthony J. Parsons and published by Springer Science & Business Media. This book was released on 2009-03-20 with total page 824 pages. Available in PDF, EPUB and Kindle. Book excerpt: About one-third of the Earth’s land surface experiences a desert climate, and this area supports approximately 15% of the planet’s population. This percentage continues to grow, and with this growth comes the need to acquire and apply an understanding of desert geomorphology. Such an understanding is vital in managing scarce and fragile resources and in mitigating natural hazards. This authoritative reference book is comprehensive in its coverage of the geomorphology of desert environments, and is arranged thematically. It begins with an overview of global deserts, proceeds through treatments of weathering, hillslopes, rivers, piedmonts, lake basins, and aeolian surfaces, and concludes with a discussion of the role of climatic change. Written by a team of international authors, all of whom are active in the field, the chapters cover the spectrum of desert geomorphology.
Download or read book Environmental Sedimentology written by Chris Perry and published by John Wiley & Sons. This book was released on 2009-03-12 with total page 460 pages. Available in PDF, EPUB and Kindle. Book excerpt: Environmental Sedimentology provides a comprehensive introduction to this rapidly expanding field which addresses the functioning and dynamics of contemporary sediment systems and how these systems respond to a range of both natural and anthropogenically-induced disturbance events. considers a range of sedimentary environments; mountain and upland, fluvial, lacustrine, arid, urban, deltaic and estuarine, temperate coastal, tropical coastal, and continental shelf aspects of sediment management and remediation are also considered as are the potential impacts of on-going and future climatic and environmental change Readership: advanced level undergraduates in earth science, environmental science and physical geography, and graduate students in the earth and environmental sciences with an interest in contemporary sediment systems
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 Landscapes and Landforms of Namibia written by Andrew Goudie and published by Springer. This book was released on 2014-10-15 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: The landscapes of Namibia are of world-class quality in beauty, diversity and interest. This book provides the first ever overview of the most important of these landscapes, explains why they look as they do, and evaluates why they are of note. Writing from a geomorphological perspective, the authors introduce the key processes and controls which influence landscape and landform development in Namibia. Geological and tectonic background, climate now and in the past, vegetation and animals (including humans) are all identified as crucial factors influencing the landscape of Namibia today. The book presents twenty one richly-illustrated case studies of the most significant landscapes of Namibia, ranging from the iconic Etosha Pan at the heart of the biggest wildlife conservation area in the north, to the famous dunes and ephemeral river at Sossus Vlei in the heart of the Namib desert. Each case study also contains a full list of the key references to the scientific work on that landscape. The authors provide an assessment of the current state of conservation of these landscapes, and their importance to tourism. The book is recommended reading for anyone with a professional or amateur interest in the spectacular and intriguing landscapes of this part of southern Africa. It provides a useful handbook for those travelling around Namibia, and an invaluable reference guide for those interested in how landscapes develop and change.
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2005 with total page 858 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 1960 with total page 332 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Geomorphology of Desert Dunes written by Nicholas Lancaster and published by Burns & Oates. This book was released on 1995 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt: Heinrich Schenker: A Research and Information Guide is an annotated bibliography concerning both the nature of primary sources related to the composer and the scope and significance of the secondary sources which deal with him, his compositions, and his influence as a composer and theorist.
Download or read book Arid and Semi Arid Geomorphology written by Andrew S. Goudie and published by Cambridge University Press. This book was released on 2013-05-27 with total page 467 pages. Available in PDF, EPUB and Kindle. Book excerpt: Based on four decades of research by Professor Andrew Goudie, this volume provides a state-of-the-art synthesis of our understanding of desert geomorphology. It presents a truly international perspective, with examples from all over the world. Extensively referenced and illustrated, it covers such topics as the importance of past climatic changes, the variability of different desert environments, rock breakdown, wind erosion and dust storm generation, sand dunes, fluvial and slope forms and processes, the role of the applied geomorphologist in desert development and conservation, and the Earth as an analogue for other planetary bodies. This book is destined to become the classic volume on arid and semi-arid geomorphology for advanced students and researchers in physical geography, geomorphology, Earth science, sedimentology, environmental science and archaeology.
Download or read book Geology of Utah s Parks and Monuments written by Douglas A. Sprinkel and published by . This book was released on 2000 with total page 676 pages. Available in PDF, EPUB and Kindle. Book excerpt: General geology papers and road logs for the Millenium Field Conference in Utah.
