Meanders<\/strong><\/p>\n Meanders are an emergent behavior of the fluid dynamics of a river, causing the river’s path to oscillate back and forth across the general downstream direction.<\/p>\n From your\u00a0specified river path, meanders are added. These can be specified in all manner of realistic (and non-) ways. Although the model is deterministic rather than simulating hydrodynamics, it does an admirable job of recreating river meanders.<\/p>\n Thalweg Behavior<\/strong><\/p>\n The thalweg of a river is the deepest part of the channel. Our river model captures the repetitive pool and rapids\u00a0behavior of a river as well as the lateral movement of the thalweg back and forth across the channel due to meander bends of the river.<\/p>\n This includes cut-banks (eroded areas on the outer sweep of a meander), slip-off slopes (shallow areas of deposition at the inside of the river bend), and point bars.<\/p>\n River Width<\/strong><\/p>\n Although you specify the average river width as part of the creation process, the GCS will vary the width of the river in a pattern relative to the meanders and thalweg.<\/p>\n This is very important, as wide\/narrow points of the river are often strongly correlated with deep or shallow areas of the river.<\/p>\n Floodplain\/Valley Shape<\/strong><\/p>\n Finally, the GCS can also describe oscillations of the valley walls relative to the meanders\/etc. Although the shape of the valley is more\u00a0influenced by factors not specifically\u00a0related to the river itself (such as hillslope erosion), including this in the GCS lets you correlate things like narrow points in the valley to the behavior of the river channel itself.<\/p>\n <\/p>\n So, that’s the geology primer, now let’s look at the actual implementation in World Machine!<\/p>\n Here’s a quick walkthrough in pictures of the River Model in action:<\/p>\n <\/p>\n Above, you can see a basic straight channel with a simple but powerful River GCS applied; the river moderately meanders back and forth across the gently rising floodplain, with all of the other parameters (depth, width, riverbank cut, etc) all varying in concert to model a basic river.<\/p>\n <\/p>\n Here’s a slightly more complicated river that also includes a surrounding valley:<\/p>\n The valley walls are included in this GCS; also, note that a distinct meander belt is present at the base of the floodplain (the shelf present near the river channel itself that, in reality, represents the area that the river continuously migrates within).<\/p>\n <\/p>\n Finally, unlike the last few images that feature the river by itself, here’s a more complete example that shows the river embedded within an actual terrain:<\/p>\n![\"\"](\"http:\/\/upload.wikimedia.org\/wikipedia\/commons\/5\/51\/Meander_in_River_Don_-_geograph.org.uk_-_1363451.jpg\")
![\"\"](\"http:\/\/courses.missouristate.edu\/emantei\/creative\/WeathStrem\/meander.jpg\")
The River Model<\/h2>\n
![\"River-Snapshot\"](\"http:\/\/www.world-machine.com\/blog\/wp-content\/uploads\/2015\/02\/River-Snapshot2.jpg\")
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