Aryana Libris

Author : Bravard Jean-Paul
Title : Sedimentary Crisis at the global scale 1 Large rivers, from abundance to scarcity
Year : 2019

Link download : Bravard_Jean-Paul_-_Sedimentary_Crisis_at_the_global_scale_1.zip

Foreword. Rivers and deltas have been essential to the human enterprise on planet Earth since the dawn of civilization, along the Tigris and the Euphrates, the Nile, the Yangtze and the Indus. Rivers provide domestic, commercial and industrial users with water, not to mention irrigation for agricultural purposes; they are a means of transport, a habitat for fauna, a source of hydroelectric production and fertile river sediment to enrich the floodplains. Some of them carry solid sediment in the form of tailings, which may affect aquatic ecosystems and be deposited on the floodplains. Transported sediment comes from the bed and banks of the river as well as the watershed of the highlands, which has consequences for the stability of the channel, every use of rivers and its floodplains. Rivers transport more sediment to the world’s oceans than all other agents, such as glaciers, groundwaters, wind, volcanoes and waves. When water rich in energy and sediment enters a low-energy water plane, low-altitude deltas are formed. These are as important for humans as they are for fauna. They can serve as a buffer against floods, but less and less efficiently as they sink and are occupied, over time, by humans. Rivers and deltas have been struck by natural disasters like hurricanes and floods. They have also been transformed by humans over the centuries, through direct manipulation in the form of dams, levees, diversions, bank stabilization, channeling/recovery, and the extraction of sand and gravel. Rivers and deltas are also indirectly affected in the watershed by human activities that modify the delicate balance between the water and sediment in the river system and that bring about change in the vegetation (deforestation/reforestation, grazing livestock, forest fires and agriculture). ...