Interactions entre l’érosion, l’hydrologie lacustre et la végétation en zone tropicale PDF Download
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Author: Yannick Garcin
Publisher:
ISBN:
Category :
Languages : fr
Pages : 0
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Book Description
Le lac de cratère Masoko (9°S, sud de la Tanzanie) a fourni un enregistrement continu des changements environnementaux au cours des derniers 45 000 ans. Une approche pluridisciplinaire couplant les processus du bassin versant et les processus lacustres a mis en évidence les différents contrôles de la dynamique sédimentaire sur ce cratère. L’étude détaillée des sédiments lacustres d’une carotte composite, a permis à partir des paramètres magnétiques, géochimiques, et des assemblages polliniques, de reconstituer l’histoire du climat et de la végétation dans cette région de l’Afrique de l’Est. A l’échelle orbitale les fluctuations du lac Masoko et les changements qui affectent la végétation locale sont contrôlés par (i) l’insolation aux basses latitudes, modulée par la précession et par (ii) les conditions aux limites liées aux variations glaciaires-interglaciaires (volume de glace, CO2). Les périodes qui coïncident avec un maximum d’insolation durant l’été austral sont caractérisées par des conditions humides dans les tropiques Sud. De même, durant les événements glaciaires les plus intenses (e.g., Dernier Maximum Glaciaire et Dryas Récent), la ceinture des pluies équatoriales s’est déplacée vers le Sud, fournissant de l’humidité aux tropiques de l’hémisphère austral et desséchant les tropiques situés au nord de l’équateur géographique. A l’échelle millénaire à centennale, l’analyse des signaux sédimentaires de Masoko montre de fortes cohérences avec les cycles d’activité solaire. Ce résultat appuie les observations obtenues sur d’autres lacs est-Africains et suggère un contrôle probable de l’activité solaire sur le climat régional. Pour la période récente, le Petit Age Glaciaire se caractérise par un climat relativement sec, confirmant le synchronisme des changements hydrologiques régionaux durant cette période. Finalement, l’impact anthropique est mis en évidence dans les sédiments du lac Masoko au cours des derniers 60 ans par l’augmentation de l’érosion.
Author: Yannick Garcin
Publisher:
ISBN:
Category :
Languages : fr
Pages : 0
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Book Description
Le lac de cratère Masoko (9°S, sud de la Tanzanie) a fourni un enregistrement continu des changements environnementaux au cours des derniers 45 000 ans. Une approche pluridisciplinaire couplant les processus du bassin versant et les processus lacustres a mis en évidence les différents contrôles de la dynamique sédimentaire sur ce cratère. L’étude détaillée des sédiments lacustres d’une carotte composite, a permis à partir des paramètres magnétiques, géochimiques, et des assemblages polliniques, de reconstituer l’histoire du climat et de la végétation dans cette région de l’Afrique de l’Est. A l’échelle orbitale les fluctuations du lac Masoko et les changements qui affectent la végétation locale sont contrôlés par (i) l’insolation aux basses latitudes, modulée par la précession et par (ii) les conditions aux limites liées aux variations glaciaires-interglaciaires (volume de glace, CO2). Les périodes qui coïncident avec un maximum d’insolation durant l’été austral sont caractérisées par des conditions humides dans les tropiques Sud. De même, durant les événements glaciaires les plus intenses (e.g., Dernier Maximum Glaciaire et Dryas Récent), la ceinture des pluies équatoriales s’est déplacée vers le Sud, fournissant de l’humidité aux tropiques de l’hémisphère austral et desséchant les tropiques situés au nord de l’équateur géographique. A l’échelle millénaire à centennale, l’analyse des signaux sédimentaires de Masoko montre de fortes cohérences avec les cycles d’activité solaire. Ce résultat appuie les observations obtenues sur d’autres lacs est-Africains et suggère un contrôle probable de l’activité solaire sur le climat régional. Pour la période récente, le Petit Age Glaciaire se caractérise par un climat relativement sec, confirmant le synchronisme des changements hydrologiques régionaux durant cette période. Finalement, l’impact anthropique est mis en évidence dans les sédiments du lac Masoko au cours des derniers 60 ans par l’augmentation de l’érosion.
Author: Martin Williams
Publisher: Cambridge University Press
ISBN: 1316832791
Category : Science
Languages : en
Pages : 425
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Book Description
The Nile Basin contains a record of human activities spanning the last million years. However, the interactions between prehistoric humans and environmental changes in this area are complex and often poorly understood. This comprehensive book explains in clear, non-technical terms how prehistoric environments can be reconstructed, with examples drawn from every part of the Nile Basin. Adopting a source-to-sink approach, the book integrates events in the Nile headwaters with the record from marine sediment cores in the Nile Delta and offshore. It provides a detailed record of past environmental changes throughout the Nile Basin and concludes with a review of the causes and consequences of plant and animal domestication in this region and of the various prehistoric migrations out of Africa into Eurasia and beyond. A comprehensive overview, this book is ideal for researchers in geomorphology, climatology and archaeology.
Author: Martin Williams
Publisher: Cambridge University Press
ISBN: 1107016916
Category : Nature
Languages : en
Pages : 653
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Book Description
A synthesis of the environmental and climatic history of every major desert and desert margin, for researchers and advanced students.
Author: Adrian M. Harvey
Publisher: Geological Society of London
ISBN: 9781862391895
Category : Science
Languages : en
Pages : 258
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Book Description
Alluvial fans are important sedimentary environments. They trap sediment delivered from mountain source areas, and exert an important control on the delivery of sediment to downstream environments, to axial drainages and to sedimentary basins. They preserve a sensitive record of environmental change within the mountain source areas. Alluvial fan geomorphology and sedimentology reflect not only drainage basin size and geology, but change in response to tectonic, climatic and base-level controls. One of the challenges facing alluvial fan research is to resolve how these gross controls are reflected in alluvial fan dynamics and to apply the results of studies of modern fan processes and Quaternary fans to the understanding of sedimentary sequences in the rock record. This volume includes papers based on up-to-date research, and focuses on three themes: alluvial fan processes, dynamics of Quaternary alluvial fans and fan sedimentary sequences. Linking the papers is an emphasis on the controls of fan geomorphology, sedimentology and dynamics. This provides a basis for integration between geomorphological and sedimentological approaches, and an understanding how fluvial systems respond to tectonic, climatic and base-level changes.
Author: Télesphore Sime-Ngando
Publisher: Springer
ISBN: 3319399616
Category : Science
Languages : en
Pages : 422
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Book Description
This book represents the first multidisciplinary scientific work on a deep volcanic maar lake in comparison with other similar temperate lakes. The syntheses of the main characteristics of Lake Pavin are, for the first time, set in a firmer footing comparative approach, encompassing regional, national, European and international aquatic science contexts. It is a unique lake because of its permanently anoxic monimolimnion, and furthermore, because of its small surface area, its substantially low human influence, and by the fact that it does not have a river inflow. The book reflects the scientific research done on the general limnology, history, origin, volcanology and geological environment as well as on the geochemistry and biogeochemical cycles. Other chapters focus on the biology and microbial ecology whereas the sedimentology and paleolimnology are also given attention. This volume will be of special interest to researchers and advanced students, primarily in the fields of limnology, biogeochemistry, and aquatic ecology.
Author: Helene Paquet
Publisher: Springer Science & Business Media
ISBN: 3642605257
Category : Science
Languages : en
Pages : 523
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Book Description
Clays and soils are of great importance in various scientific fields, such as agriculture and environmental science, and in mineral deposits. Students and close collaborators of Georges Millot, the eminent French clay sedimentologist, have put together a book with topics ranging from weathering processes and diagenetic evalution of sediments to sedimentary mineral deposits. The book is of interest to practitioners, advanced students as well as teachers in the above fields.
Author: Jacqueline Ki-Zerbo
Publisher: Univ of California Press
ISBN: 9780520066960
Category : History
Languages : en
Pages : 372
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Book Description
"This volume covers the period from the end of the Neolithic era to the beginning of the seventh century of our era. This lengthy period includes the civilization of Ancient Egypt, the history of Nubia, Ethiopia, North Africa and the Sahara, as well as of the other regions of the continent and its islands."--Publisher's description
Author: Eric Servat
Publisher:
ISBN: 9781901502121
Category : Arid regions
Languages : fr
Pages : 518
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Book Description
Author: Éloi Ficquet
Publisher: LIT Verlag Münster
ISBN: 3643904762
Category : History
Languages : en
Pages : 224
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Book Description
One hundred years ago, from 1910 to 1916 the young prince Lij Iyasu (1897-1936) assumed power as the uncrowned emperor of Ethiopia. However, he was overthrown by an alliance of oligarchs led by the future emperor Hayle Sillase. The short reign of Iyasu, disrupted by fierce inner competitions in the international context of World War I, has remained obscure, even to specialized researchers. Yet, over the past two decades, new sources have been uncovered, allowing for new questions and searching for new answers. This book assembles diverse perspectives on Lij Iyasu's politics and life, his 'pluralistic' and controversial religious inclinations, and his international relations. (Series: Northeast African History, Orality and Heritage - Vol. 3)
Author: Willem Willems
Publisher:
ISBN: 9789088903861
Category : Business & Economics
Languages : en
Pages : 434
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Book Description
Water is vital for life, and its availability has been a concern for mankind throughout the ages. Its presence has always been ascertained in a variety of ways and the development of human society everywhere is connected with various forms of water management. Man also needed to manage water to find protection from its dangers and the need for that is increasing. In the coming decades, the impact of climate change is expected to intensify floods and droughts, affect groundwater resources, raise sea levels, increase pollution and enhance the frequency and magnitude of disasters. Societies around the world are challenged to adapt to these threats to ensure water security, economic prosperity and environmental and cultural sustainability. This book deals with the heritage of water management and the use that was made of water, as well as the impact of water management on heritage. An example of the former may be an ancient irrigation system in the Filipines or in the Middle East that still functions today, while the latter may reflect the importance of maintaining groundwater levels for the preservation of organic remains on archaeological sites or of wooden piles underneath standing buildings. In either case the papers in this book reflect the dynamic nature of water, and hence the equally dynamic relation between water management and heritage. This publication follows up on a Heritage and Water conference in Amsterdam, the first of its kind. Its main purpose is to credibly present the importance and value of heritage and historical experience for water and sustainable development, and vice versa, present the importance of water management for the protection of heritage. It presents evolving insights and concepts about Water and about Heritage from a variety of disciplines, policy and public perspectives illustrated with cases studies and aims to connect decision makers with experts such as engineers, archaeologists, historians, geographers, ecologist and landscape architects
