Page 521 - Geosystems An Introduction to Physical Geography 4th Canadian Edition

THEhumanDENOMINATOR 15 Rivers, Floodplains, and Deltas
RIVER SYSTEMS HUMANS
• Humans use rivers for recreation and have farmed fertile floodplain soils for centuries.
• Flooding affects human settlements on floodplains and deltas.
• Rivers are transportation corridors, and provide water for municipal and industrial use.
HUMANS RIVER SYSTEMS
• Dams and diversions alter river flows and sediment loads, affecting river ecosystems and habitat. River restoration efforts include dam removal to restore ecosystems and threatened species.
• Urbanization, deforestation, and other human activities in watersheds alter runoff, peak flows, and sediment loads in streams.
• Levee construction affects floodplain ecosystems; levee failures cause destructive flooding.
15a
In June 2013, floodwaters following days of heavy rainfall inundated Germany, Austria, Slovakia, Hungary, and the Czech Republic. According to local residents, water levels in Passau, Germany, were higher than any recorded in the past 500 years. [Matthias Schrader/ AP Photo.]
15b Rivers in Madagascar carry an enormous sediment load as a
15c
In 2011, Americans spent USD
$42 million on fishing-related activities. Streams in Montana, Missouri, Michigan, Utah, and Wisconsin are of high enough quality that they are designated “blue ribbon fisheries” based on sustainability criteria such as water quality and quantity, accessibility, and the specific species present. [Karl Weatherly/Corbis.]
result of deforestation. The trees anchor the soil with their roots; when that stabilizing effect is gone, soil erodes into river channels and is carried into oceans, disrupting coral reefs and other aquatic ecosystems. [Kevin Schafer/Alamy.]
NASA.
ISSUES FOR THE 21ST CENTURY
• Increasing population will intensify human settlement on floodplains and deltas worldwide, especially in developing countries, making more people vulnerable to flood impacts.
• Stream restoration will continue, including dam decommissioning and removal, flow restoration, vegetation reestablishment, and restoration of stream geomor- phology.
• Global climate change may intensify storm systems, including hurricanes, increasing runoff and flooding in affected regions. Rising sea level will make delta areas more vulnerable to flooding.
geosystemsconnection
While following the flow of water through streams, we examined fluvial processes and landforms and the river-system outputs of discharge and sediment. We saw that a scientific understanding
of river dynamics, floodplain landscapes, and related flood hazards is integral to society’s ability
to perceive hazards in the familiar environments we inhabit. In the next chapter, we examine the erosional activities of waves, tides, currents, and wind as they sculpt Earth’s coastlines and desert regions. A significant portion of the human population lives in coastal areas, making the difficulties of hazard perception and the need to plan for the future, given a rising sea level, important aspects of Chapter 16.
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