Mass wasting
what can we do to live more sustainbly? 4
1. reduce independence on heavy metals and fossil fuels 2. reduce our destruction of nature/ overproduction of resources 3. reduce our dependence on synthetic chemicals that persist in nature 4. ensure we are not stopping people globally from meeting there needs
How much of the worlds total energy budget is used by the US, every year?
28.5 trillion kwh/ year (97 quads) world total: 511 quads a year
What percentage of the global oceans have we impacted? What about terrestrial ecosystems? What percentage of fisheries stocks are collapsed or overexploited
58% stocks collapsed or overexploited
What is the approximate population on earth, currently
7.125 billion
How much do mass wasting events cost us annually in the US?
>$1 billion in damages
what drives mass wasting events?
Gravity
what three factors do we use to clarify mass wasting events
How material moves (falls vs flows vs creeps vs slides) Type of material (solid-ie, big chunks of rocks vs unconsolidated-i.e., sediment, loose rocks) Rate of movement (fast vs slow)
how does the input of fluid impact slope stability? know how this changes as water content increases
Some water increased cohesions (surface tension holds grains together) too much water pushes grains apart
Antropocene?
a proposed epoch that begin when human activities start to have significant global impact on earths geology and ecosystems
What is regrading, and how does it work
changing the angle of the slope to stabilize the slope trying to get closer to the angle of response
What holds a steeper slope, consolidated or unconsolidated material? what is the name for the angle that a pile of unconsolidated material will hold?
consolidated angle of response
how does material behave during a flow event? how does an earth flow differ from debris flow? which is usually faster?
earth flow moves and behaves like a fluid- speed is variable. debris flows is rock fragments supported by a muddy matrix- speed is up to 100 km/hour earthflow: finder grained material moving at a slower pace
what general concepts does the UN Brundtland Report address?
eventually earth will run out of its resources: not unlimited
how does a flow differ from a slide, in terms of how material moves?
flows: material moves and behaves like a fluid-speed variable slides: material moves as cohesive whole along defined plane
Where do we get most of our energy? what do we burn
fossil fuels
Rock falls
free falling rocks
what process commonly drives creep, and how fast does it occur? be able to recognize an image of trees that have experienced creep.
frequently related to freeze- thaw cycles. freezing: soil particle moves up, perpendicular to slope thawing: contraction
how long has it taken us to increase in population size from 1 billion people to where we are now?
from 1804 to now
creep
gradual, generally related to freeze thaw
What are our five ways to prevent mass wasting? You showld know how these work as well.
hazard mapping and zoning restrictions revegetation regrading:stabile slopes reinforcement improve drainage
What drove the OSO landslide, and what did the past history of landslides on this slope look like? What factors contributed to its unusual behavior, relative to what we might have predicted?
long history of landslides in that area, weakly consolidated sediments, soil saturation from heavy rainfall and groundwater matrix
flows
material behaves as a fluid. includes earth flows, debris flows, avalanches
landslides
material slides along defined plane
Is more surface material excavated by us, or by natural processes?
more material is excavated by human actions. 700 million metric tons compared to 550 million metric tons
How much water do you need each day to survive? how much (in the US) do you use, and where does it go?
need 5 L (1.3 gallons). The Us uses 4455 L a day Faucet, washer, toilet, etc big sink= ocean
What different observations allow us to predict potential future slope failures? You should know the list of possible clues.
past slopes steep slopes changes in slope potential triggers (rainfall, earthquakes, volcanic events)
How does physical water scarcity differ from economic water scarcity, and how many people experience each of these conditions?
physical scarcity= countries/entities withdraw > 75% river flow for agriculture,industry, and domestic purposes economic scarcity= access limited due to corruption, lack of infastructure, poverty
rock slides
rock slide along plane
How does vegetation impact slope stability?
roots of plants will hold soil together and pull out some of the water
what are some of the events that can trigger mass wasting events/ slope failure
seismic events (earthquakes) Volcanic events (can trigger lahars by melting snow) Heavy rainfall Snowmelt
What allows avalanches of snow to move so quickly? (what supports them and acts as a fluid?)
speed results from high air or water contents and steep slopes. carries wit it everything in its path
What is the carrying capacity of the world (both what does this term mean, and how many people can the world support, given the different potential consumption levels we could all try to attain
the ecological footprint resources, fresh water and food
Can a landslide ever change into a debris flow? How?
yes, addition of water and loss of sediment cohesion can transform a slide into a flow during a single event
Does any place in the US experience water scarcity?
yes, in the south and west
Is Iowa at risk for mass wasting events?
yes, intermediate danger