Fluvial Landscapes

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Overview

meanders of the Owen's river as seen from satellite view

Owens river south of Bishop, CA.
Google imagery

Water is a powerful geomorphic agent. Water in rivers and streams on earth makes up only 0.003% of all fresh water on earth yet rivers have a great deal of influence on the surface of our planet. Water wears away at bedrock, carries sediment and is the dominant force reshaping nearly every landscape. These fluvial landscapes are constantly changing as precipitation, meltwater and groundwater supplies vary and river levels rise and fall. They operate on short (days/weeks), medium (decades), and long (centuries) time scales.

fluvial (flu'-vi-al) Of or pertaining to rivers; produced by the action of a stream or river

When water falls on the ground some of it is absorbed, and the remainder runs over the surface through sheet or overland flow. The water follows the pull of gravity and runs to lower areas, eventually collecting in the stream basins. As water moves over the landscape it dissolves some of the minerals that it passes over. The water will also pick up and carry small particles and push larger particles over the surface. Through these processes, flowing water can drastically shape a landscape over time.

A drainage basin or watershed is the terrain surrounding a stream valley that contributes to the water and sediments carried by the stream. Streams flow along channels which are situated in the lowest parts of valleys. The channels are linked together as a 'drainage nework'. Drainage networks develop like branches on a tree starting at the tips and collecting toward the trunk.

How to take this field trip

Fluvial landscapes are found all over California. Even where water is not a perennial presence in a landscape, such as California's many dry environments, fluvial activity in the form of flash floods has a profound effect on the shape of the land surface.

Recall the methodology that we discussed in our home room. In this module, we will visit five locations around California to examine channel development, bedrock channels, and alluvial channels. You will be asked to make observations, and we will go over them together. Then we will look in depth at the processes involved in the formation of the landform. Finally, you will apply what you have learned by visiting additional locations that have been affected by the same geomorphological processes.

The map below shows the five stops we will be making on this trip. The first will look at channel development in the Carrizo Plain and make general observations about the morphology of fluvial landscapes. Next, we will visit Fossil Falls in the southern Owens Valley to examine bedrock river channels. We will then examine two types of alluvial channels, the meandering channel of the Owens river in Owens Valley, the artificial channel created for the Owens River where it is diverted into the LA Aqueduct, and the braided channel of the Cuyama River on the eastern edge of the San Rafael Mountains. You can zoom in on these maps and change the view if you wish to get a better idea of where we are going.

yellow=bedrock river, red=channel development, purple = braded river channel, blue = meandering river channel, light blue = man-made channel
View fluvial field trip stops in a larger map

To take this virual field trip, start at the top of each page. Read the short summary, then interact with the visualizations. Finally, to navigate to the next page, click on the Next link at the bottom of the screen. You can also return to the previous page by clicking the Previous link, or jump to any section within Fluvial Landforms using the navigation links at the top of the screen.


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