Ch 6a: Hydrosphere Flashcards
Define hydrologic cycle
Natural cycle of water movement at or near the surface of the Earth
Energy from gas to liquid
energy is released
Energy from liquid to gas
energy absorbed
Melting & Freezing do not take as much energy as
Phase change from liquid to gas
Define Latent heat
Amount of energy that is locked up in the system during phase change
Phase Change either
requires energy or lose energy
Characteristic of Water
bond mainly covalent but electron spend more time near oxygen due to polarity
Water is what kind of fluid
miscible fluid: excellent solvent for ionic and polar substances
Surface water:
rivers, lakes
Surface water is the ____ of the reservoirs
smallest but most visible
Surface water is a major
modifier of the landscape, largest natural movement of matter and sediments. Used to build deltas
Un-channeled flow is
overland or sheet flow
Channeled flow is
streams
River Systems:
streams are organized in river systems, tributaries typically merge downstream.
Define tributaries
river or stream flowing into a larger river or lake
Drainage basin:
area drained by a major river, separated by drainage divides
Drainage Styles depends on…
depends on topography and geology of the drainage area
Drainage Styles:
Dendritic, radial, rectangular, trellis
Drainage styles: dendritic
tree-like branching pattern, typical of terrains with uniform bedrock, stratified sedimentary or massive rocks
Drainage styles: radial
radial pattern, away from a central high point. eg. volcano
Drainage styles: rectangular
Follows 2 directions, at right angles, mimics pre-existing fractures of joint sets in bedrock, not much sedimentary rock
Drainage styles: Trellis
parallel stream systems, develop in valley and ridge terrain
Distributary
referred to as channels, root like
Characteristics of stream flow:
streams show variability in
gradient, velocity, discharge
Stream Flow Char: Velocity
velocity of flow varies within channel, slowest at base and sides, viscous drag
Stream Flow Char: Discharge
Volume of water passing a given point in unit time. Q = A* Vavg
Stream Flow Char: Gradient
Gradient decreases, steeper at the beginning and shallows out at the bottom
Sediment Transport
Competence and capacity of the stream depends on fluid velocity.
Methods of sediment movement
suspension, rolling and sliding on the bed (creep), saltation
Load types:
suspended load, bed load, dissolved load
Load types: suspended load
mainly silts and clays, some saltation of sand. will flow
Load types: bed load
coarsest material, movement through creep, traction or saltation
Load types: dissolved load
suspension, ions in solution
Downstream variation in sediment
net effect: downstream fining.
Downstream variation in sediment: suspended load
deposited when velocity drops
Downstream variation in sediment: dissolved load
typically carried to sea and precipitated out. eg. limestone or salt. Deposited as non-clastic sediment
what are Channel Patterns, and what do the types depends on
typically carve V-shaped valleys, the type depends on the channel shape and number of internal channels
Channel Patterns types:
straight, braided, meandering, anatastomosing
Channel Patterns: straight
single channels with low sinuosity. Characteristic of: young streams, areas with steep gradients
Channel Patterns: Braided
several small channels that join, low sinuosity, channels separate by islands or river bars of coarse materials
Channel Patterns: anastomosing
similar to braided, multiple channels within a larger channel, gradient is low, lots of finer sediments, lots of vegetation, steep, stable sides
Channel patterns: meandering
single channels, high sinuosity, older streams and areas with low gradients, sediment supply low to moderate and fine grained
Meandering migration
meander loops migrate downstream, highest velocity at the outside of the curve, lower velocity on the inside. Sinuosity increases with time
Meander loops: outside of the curve
higher velocity leads to erosion (cutbanks, thalwegs)
Meander loops: inside of the curve
lowest velocity leads to deposition (point bars)
Floodplain
typically alternating beds of silt and clay, grain size decreases away from the channel. bigger pieces of sediment rests near the edge
Flooding rivers
occurs when river level exceeds the channel banks
Terraces
former floodplains, pair or unpaired, result of stream incision and regional uplift
Alluvial Fans
Large, fan-shaped accumulations. Along the flank of a mountain, drier climates, form when channel opens into a valley or plain
Deltas
roughly triangular shaped deposits, form when a stream enters a standing body of water (Ocean/Lake). River may become divided into distributaries
Lakes
Standing bodies of water, many ways to form them. In general, an obstacle to flow is necessary. Most are geologically short-lived.