13.5.1 Moving water Erosion, transportation and deposition are the key processes rivers use to sculpt landscapes. Perennial rivers, such as the Gordon River in Tasmania, flow all year. Others, such as Cooper Creek in Queensland, are intermittent and have seasonal flows. Water is constantly moving through the water cycle; it evaporates from the surface and returns in the form of rain. It flows across the surface of the Earth into streams, eventually flowing into water bodies or soaking through rocks and soil into groundwater . Groundwater is essential for keeping rivers flowing in dry months and preventing them from running dry.
FIGURE2 Rivers of the world: the longest river on each continent
Nile River (Africa)
Amazon River (South America)
Yangtze River (Asia)
Mississippi–Missouri River (North America)
Murray–Darling River (Australia)
Volga River (Europe)
Gascoyne River (Western Australia)
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SkillBuilder discussion Geographical inquiry 1. Look at FIGURE2 . How does each of these rivers compare to the Yarra River that runs through Melbourne? 2. What is your ‘local’ or closest river? Where does it start and end? How long is it? River systems and features All parts of the Earth are related to the formation of river landscapes: • The lithosphere (rocks and soil) • The hydrosphere (water) • The biosphere (plants and animals) • The atmosphere (temperature and the water cycle) Changes to a river can happen quickly or gradually. Any change can impact other locations along its course. 13.5.2 Rivers flow downhill; the source (start) will be at a higher altitude than its mouth (end). A fast-flowing flooded river will erode and transport large amounts of material downstream . As water speed or volume decreases, much of this material will be deposited. Rivers have three main sections — the upper, middle and lower course. Different processes and landforms are associated with each section ( FIGURE3 ).
300 Jacaranda Humanities Alive 8 Victorian Curriculum Third Edition
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