Embedded Files
Controls:
Q= adjust flow rate in the flume, in the world would be snow or rain or groundwater discharge
S= grade the bed, or rotate the table forward or back, in the world it would be tectonics and baselevel changes
Qs= adjust flow rate or slope or base level, it essentially depends on slope and discharge from above, there's also some impact of grain size. larger grains require more power.
Profile= Easiest way is by adjusting the base level
Baselevel= by moving the little spigot at the bottom up or down. in the world it would be the creation or destruction of a lake (damns being a clear one) or change in sea level.
Geomorphic Processes
Geomorphic Mechanisms
This shows all of the processes: bed and bank erosion, deposition and sediment transport. Bed erosion are the little grains moving from the bottom of the stream, bank erosion are the ones coming from the banks. Deposition are the grains settling and stopping, Transport is just the grains moving without being plucked off of anything and/or settling and stopping.
meandering and braiding meanders are the big swoops and braiding is the multi threaded channels
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V
It's described in the video but an avulsion is when a flow channel is abandoned and a new one is formed, commonly seen in deltaic areas.
grain sorting occurs due to differences in grain size and the ability for the flow to carry said grains.
Very clear showing of how structures can wildly change the bed.
Meandering?
A true single threaded meandering stream was not observed. We got meanders, however they were multi threaded channels. The keys to a single threaded meandering stream are vegetation roots and strong cohesion between clay particles in the system. The flume does not easily have these controls. The best way I can think of is by getting a root simulative matrix to stabilize the "soil". Whatever it is, it would take some engineering.
Events
Done by significantly increasing the flow velocity. There overall is a lot of scouring during such a process. There is high deposition at base level during these events since there is so much erosion in the channel.
Done by adjusting the flow velocity slightly. The processes appear to be definitely erosion of the bed but there is also some bar creation just downstream from erosion zones. Overall varied and dynamic responses
This was done by changing the base level of the channel. Overall there was a longitudinal change in the entire channel to adjust to the base level change to meet a nice concave profile.
Questions
From what you did, what seems to be the roll/impact of small flood vs. big flood?
small floods in general were reworking a reach, however big floods seemed to be scouring the reach. Large floods eroded significantly more sediment and had little deposition while small floods actually had some deposition within the system
In your experimentation, did you observe overbank flows, bankfull flows and/or baseflow flows?
Baseflow would be analogous to a relatively low flow rate and the soil was saturate so there was some flow coming out of the pore space. Bankfull was observed during the small floods. Overbank flows were observed during large floods and when the channel was impounded with no outlet, it would overflow the banks.
What role did hyporehic flow play in what you observed?
Hyporehic flow likely played a large role since the soil was entirely saturated, meaning the pore space was very filled up. That allows geomorphic work to be done easier and it also contributed to flow conditions. We also saw some chute dissection (see video) from hyporehic flows alone with baseflow conditions from the water within the pores.
What roll did recession limb flows seem to play in what you observed?
Recession limb flows were just elevated flows from a flood surge, however approaching the baseflow condition. It seemed to take a little longer for flows to return to base flow than it took for the flows to reach peak flow. That aided in the geomorphic work done within the flume since there were these intermediary flows of varying powers rather than a singular large flood pulse flow. I am not entirely sure about just how much work was done compared to rising limb, however the main picture of "intermediate varying and settling flows allowing dynamic work to take place" is still true and important in geomorphic work because it determines geomorphic units and bedform units.
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