Скачать или смотреть Streams & Floods – The Geology of Running Water | Chapter 17 – Earth: Portrait of a Planet

In Chapter 17 of Earth: Portrait of a Planet, Stephen Marshak explores the dynamic and often destructive power of streams and floods, emphasizing how running water sculpts the landscape, forms life-sustaining features like valleys and floodplains, and poses major natural hazards. The chapter begins with the origin of stream channels, the formation of drainage networks, and the structure of watersheds, introducing key processes like downcutting and headward erosion. Marshak describes the mechanics of stream flow, including discharge, velocity variations, and the transport of sediment as dissolved load, suspended load, or bed load. The chapter also explains how rivers shape land through erosion, deposition, and features like braided streams, meanders, oxbow lakes, natural levees, alluvial fans, and deltas. It covers stream evolution over geologic time, including stream rejuvenation, drainage reversals, and antecedent streams, then transitions to the causes and types of floods—from slow-onset to catastrophic flash floods. The chapter closes with human impacts on streams, such as pollution, damming, urban runoff, and how climate and infrastructure shape our future interactions with river systems.

📚 Key Topics in This Chapter
🔸 Formation of streams: sheetwash, downcutting, and headward erosion
🔸 Drainage networks: dendritic, radial, rectangular, trellis, parallel
🔸 Watersheds, drainage divides, and the continental divide
🔸 Stream discharge, flow velocity, and turbulence
🔸 Sediment transport: competence, capacity, and sediment load types
🔸 Valley vs. canyon formation, rapids, and waterfalls
🔸 Braided vs. meandering streams and how meanders evolve
🔸 Formation of floodplains, natural levees, and deltas
🔸 Stream rejuvenation, incised meanders, stream piracy, and drainage reversal
🔸 Causes and types of floods: slow-onset floods, flash floods, glacial outburst floods
🔸 Flood control methods: levees, floodways, dams, and flood-hazard mapping
🔸 Human impacts: river pollution, dam construction, urbanization, and agriculture







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