Quiz 2 Notes

Quiz 2 Notes - Lab 9 Fluvial Geomorphology the study of the...

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Lab 9 Fluvial Geomorphology – the study of the processes and landforms created by running water at the Earth’s surface - running water erodes, transports, deposits minerals and inorganic material - other flowing substances includes waves, wind and glacial ice o basic physical relationships control stream behavior and channel formation 1) Running Water - flows as a sheet across land surface, picks up particles and moves them downslope into the stream channel o large/heavy rainfall moves large amounts of sediment downstream o this is how erosion of hills and mountain occurs carving valleys depositing sediment Denudation - total of all processes that exposed rocks are worn away resulting in sediment that are transported to the sea or inland basin o results in an overall lowering of land surface Stream Load - amount of material that a stream carries at any one time - material comes from the channel through which it flows Carrying Capacity - the actual amount of sediment a stream is capable of carrying 2) Channel Form - shape of the river is controlled by topography - straight channels are rare – only occurs in short distances Braided Stream - many interconnected shallow channels - form when the sediment load is larger than the stream energy required to carry the load Meandering Stream - a single winding channel - formed on broad shallow slops allowing stream to move freely over the topography - has enough energy to deposit and remove sediment Aggrade – deposit sediment forms point bars Degrade – removes sediment forms undercut banks These two processes can cause meanders to migrate and cause some to get cut off
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- Oxbow Lake – a cut off meander Thalweg – imaginary line connecting all the deepest points in a channel aggradation typically occurs opposite the thalweg 3) Fluvial Landforms - most rivers in humid climates have a floodplain - floodplain – the broad and flat ground immediately on one or both sides of a river - alluvial fan – a sloping conical accumulation of coarse aggradation o found at the mouth of a canyon or ravine with the fan spreading out into the adjacent plain 4) Stream Velocity and Channel Geometry - aggradation and degradation relate directly to the stream velocity and mean particle size within the channel Calculation for stream velocity: Velocity = (s)(r)/n S = slope (rise over run) R = hydraulic radius(area/wetted perimeter)=(width x depth/width +2(depth)) N = empirical coefficient of surface roughness Hydraulic radius – measures the energy in a stream channel Wetted Perimeter – the portion of the channel that touches the water in the channel 5) Stream Order - the relationship between a channel and the connecting tributaries - stream order is assigned to improve management of river systems - Guidelines for ordering streams o 1 st order streams have no tribuaries o when two streams of the same order merge, the resulting merged channel becomes the next highest order o when streams of different order merge, the resulting stream remains
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Quiz 2 Notes - Lab 9 Fluvial Geomorphology the study of the...

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