This site focuses on channel forms created on a stream table in the Department of Geography and Geology at the University of Nebraska at Omaha. There is an overview site discussing stream table modeling of river (fluvial) systems in general, and a site that focuses on the depositional fan/deltas created.
In the left photo, taken about 5 hours after flow was initiated, is a low-angle oblique view of the channel and its source. Note the bends and the steep cut bank. The lower portion of the cut bank is being formed at present, but the upstream portion was formed when the main channel meandered back to the right. Note the scalloped edge of the bank - this is due to small slumps that contributed to cut bank formation. The main channel is fed by two channels at the head. The right photo is a map view of the two feeding channels. Channel b will continue to develop and channel a will be abandoned, and then later destroyed by later channel migration and flood plain development. The channels are fed by a combination of seepage from the sand (equivalent to groundwater fed), and by shallow standing water in slight depressions. This differs significantly from many natural river systems that are fed over the span of the drainage basin by precipitation. These channels may be more similar to some seen on Mars, where a periodic release of water from the ground is thought to have occurred.
This is an oblique upstream view after about a day had passed. For reference, the scar of channel a in the above is image is marked. This channel has been abandoned, and it is evident that channel b has developed quite a bit. It has undergone headward retreat (cut up slope towards the source), has grown in sinuosity, and has shifted from point A to point B in the process. Some parts of the inner bend now elevated above the present channel could be considered a small scale erosional terrace. Note that there is a new branching pattern at the channel system head. This will undergo a similar history to the previous branching system (evident below), with the left channel becoming the main channel, and the right one abandoned. Note also the marked lensoidal sand bodies farther down. These are featured in the map view photo below.
This is a map view photo of the middle section of the photo above. The main channel meanders within a wider stretch created by past migrations of the channel, truncating old meander scars. This area might be considered similar to a flood plain, although in the stream table it is an erosional surface, while in real river systems it is often a depositional surface due to flooding and variability of sediment grain size being transported by the river. The channels do split and meet around the lensoidal sand bodies and this geometry could be considered as replicating a braided channel system such as is evident in the Platte River. Similar patterns of meandering channels truncating old channel scars can be seen in air photos of some flood plains. Note also that collections of coarser grains occurs within some of the channels illustrating the process of sorting.
This oblique photo looking upstream was taken after about two days worth of flow. Careful comparison with the above photos allows insight into channel system evolution. Several abandoned channel scars are evident and marked to the right, including channel a. A sharp meander bend has developed. The presently active channels continue to form a braided system. Some downcutting has occurred and an elevated surface that is similar to an erosional terrace, is marked. A possible equivalent can be seen on the other side so you might consider this a paired terrace.
If you have any questions or comments about this web page please contact Harmon D. Maher Jr. at University of Nebraska at Omaha (firstname.lastname@example.org). Thank you!