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29 Cards in this Set
- Front
- Back
_____ is an area where the surface runoff from precipitation onto the land and flows together toward lower areas such as lakes or oceans.
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Watershed (drainage basin)
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____ is the volume of water flowing past a specific point on the river per second.
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Discharge
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Discharge depends on the size of _____ and amount of ______.
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Watershed, participation
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Discharge (m 3/s) = ___ (m2) X ____ (m/s).
How streams respond to changes in the amount of water they carry |
Area, velocity
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______ is building roads; paved parking lots spreading across formerly vacant land (important in the Springfield area)
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Urbanization
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____ ___ flooding occurs as urbanization increases impermeable surface because rain water enters stream rather than soaking into the ground as it did prior to urbanization
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Hidden Valley
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_____ are plots of river discharge for heights in some cases over time.
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Hydrographs
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The highest point on the curve above flood stage represents flood ____.
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crest
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The _____ interval for an annual flood ranked 5 in the example of 1997-2006 period is 2 years - this flood level is reached or exceeded every two years on average.
Example: 2006-1997/5+1 = 9+1/5 = 10/5 = 2 *Big problem - this is a very short record |
reoccurance
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Flood probability = P=1/R1
A 100 year flood has a 1 in 100 chance (1%) of occurring in any given ____. |
year
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There is no meterological or statistical prohibition against ____ than one 100 year flood occurring in a century, or even a year
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more
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Whatever the cause, it is clear thatover the last 35 years the Chehaly River has produced more ___ ___ ____ than previously did.
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big time floods
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Urbanization, artificial leves and other human generated changes can alter the ___ and ___ of runoff and cause floods to become more common.
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amount, timing
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Storm surge flood, Galveston, TX reported ____ deaths, Sept. 1900.
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6,000
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____ ____ assesses stone stability, ratio of resisting force to driving force. More than 1 = close to being ____, 1.5 or 2 the resisting forces are much greater than the driving forces and the slope IS stable.
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Safety factor, stable
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Water content in slope materials affect stability in 2 ways:
1- increased water, increased weight, increases driving force= ___ likely slope failure will occur. 2 - increased water can _____ internal resisting forces. |
more, decrease
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If material becomes saturated the pressure of the water in the material (pore pressure) _____.
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increases
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Rising ___ _____ counteracts the driving force of gravity thus decreasing the resisting forces.
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pore pressure
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____ does NOT act like a lubricant. It is the pore pressures opposition to gravity.
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Water
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"___" means that more than half of the particles are larger than sand grains and the mixture has a consistency of wet concrete (debris flow)
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Coarse
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____ is a very slow type of earth flow that moves at a speed of one millimeter per year, driven by cycles of _____ and _____.
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Creep, freezing, thawing
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Gradual settling or sudden collapse of level or gently slopping land - _______.
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Subsidence
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____ - floods during high tides, the square floods (built in ____ land). Venice has ___ ___ 250+ days a year.
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Venice, swamp, aqua alta
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___ ___ is the onshore flow of water (storm surge) from the Atlantic Sea that coincides with high tides.
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Aqua alta
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The karst landscapes are characterized by ____, ____ and ____ that disappear below ground or suddenly appear as streams.
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sinkholes, caves, streams
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Natural causes of ___ ____ include above-normal rainfall, earthquakes, wildfires and slope steepening.
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slope failures
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Mitigating ____ ____ - avoid by living away from steep slopes, canyon bottoms and mouths for debris flows.
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debris flow
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The outlet of debris flow convergence structure are ___ ____ and ____ ____.
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debris basins, outlet walls
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____ ___ - sometimes this approach works, but often times the flows are so large that they over top the ____ and cover the houses below.
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Debris basins, basins
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