Chapter 8 Flashcards
Rivers, Lakes and Landscapes
Overland flow
water that travels as unconfined sheets
Stream flow
Water that travels in confined channels
Groundwater
Soaked-in water that is present at the surface of the Geosphere
Base flow
Component of water, that initially soaks in to the ground and enters a stream through its base
Channel Gradients
Measured as metres per kilometre gradients.
Sinuous flow
Many bends causes it to flow fastest on the outside curve of each bend and more slowly on the inside curve
Discharge
The amount of water that flows through a stream. m3/second
Hydrographs
Graphs of river discharge at one point in a stream, plotted against time, typically over periods of one to many years.
Tributaries
Smaller streams that flow into larger rivers
Drainage basin
The area drained by a major river and its tributaries
Downcutting
Lowering of the floor of the channel as material is eroded
Slot canyon
a valley with almost vertical sides usually with rocks of the side
Mass wasting
Gravity-driven process that bring material down valley sides into the channel
Scree or talus
Fallen rock material may accumulate at the base of a steep slope.
Slides
Coherent masses of rock or soil, that move above distinct failure surface.
Translational slide
Failure surface is approximately planar.
Rotational slide
Failure surface is curved. Upper surface of the moved material is tilted inwards, toward the failure surface.
Flows
Masses in which the moving material loses coherence as it moves, behaving more like a liquid
Slumps
Material moves down slope in a slide it may become progressively more disrupted.
Laminar
All material is transported roughly parallel to the base of the flow
Turbulent
material is carried by swirling movements in the flow, but deposits of debris flow are typically poorly sorted.
Creep
Slow movements, occur on slopes where they are promoted by changes in the amount of water in the soil.
Solifluction
When ice melts, the grains settle more vertically downwards
Headward erosion
Rapidly downcutting streams oversteepen the region around their headwaters, causing their valleys to extend in an upstream direction
River Capture or piracy
Headward erosion may cause one stream to cut into another’s valley, eventually diverting the water in the process
Lateral erosion
Rivers with low gradients carry out erosion by widening their valleys, rather than deepening them.
Floodplain
Lateral erosion gradually pushes out the sides of the valley
Alluvial fan
dumping of large amounts of sediment at a break in slope, forming multiple distributaries.
Fluvial
Sediments deposited by rivers
Braided systems
Multiple channels that branch and rejoin repeatedly downstream
Meandering Systems
Later erosion causes a single channel to migrate sometimes across a broad valley
Point-bar
Deposition, typically of sand, occurs on the inside of the curve where the current is slower
Ox-bow lake
Isolated meander channel
Natural levee
Rapid deposition at the edge of a channel may deposit a raised bank.
Terraces
Flat areas part-way up the valley sides
Lakes
Standing body of water filling a depression on land
Open Lakes
Lakes which have an outlet with discharge comparable to the inflow that provides water to the lake.
Closed lakes
Have an inlet stream but no outlet stream. Water is reduced by evaporation. Arid climates
