Anthropogeomorphology Flashcards
(36 cards)
Viles quote on anthropogeomorphology
‘Human impacts and geomorphology are all-pervasive and geomorphology textbooks need re-writing’
what are the two types of effect that humans can have?
Cumulative
Systematic
what is a cumulative impact?
building up of impacts across the world that add up to response in global systems
(eg. shaping river channels, coastal protection and quarrying)
what is a systematic impact?
whatever we do has an almost instantaneous effect on global change
e.g. climate change
Quote for anthropocene- and name/date
Steffen, 2010
Anthropocene is an epoch when human activities have ‘become so profound and pervasive that they rival, or exceed the great forces of Nature in influencing the functioning of the earths system’
Why is there contestation over when the Anthropocene started?
Because 3 potential stages:
Paleoanthropocene
industrual era
Great accelleration
how much sand is extracted each year?
50 billion tonnes
what is the use of sand?
concrete
microchips
glass
Effect of cities on geomorphology?
air pollution
enhanced surface relief - complex topography that influences wind flow and microclimates
concrete = decreased surface permeability
Tunnelling/ sewers and extraction of groundwater = cause surface instability
New sinkhole method of formation nothing to do with limestone
example of anthropogenic sinkhole
Guatemala City, 2010
rain from tropical storm Agatha
alongside volcanic eruption and leakage from sewer pipes created giant sinkhole in the city
Who coined the term ‘Anthropocene stream’ and what is this?
Merrits et al (2011)
a stream characterised by deposits, forms and processes that are the result of human interface
Explain the effects of deforestation on meanders
trees encourage stable meanders through mechanical stabilisation of river channels and retention of sediment that can create flood plains
Continued removal of trees is reverting some river landscapes to pre-vegetative conditions where sediment and the river channel were more mobile
both vegetated and barren landscapes exhibit meanders - vegetated just more stable
river deforestation increase rate of channel migration
Horton et al date?
2017
example of effects deforestation on meanders- study
Horton et al (2017)
Kinabatangan River in Malaysia -
huge areas of forest around the river cleared for palm oil monoculture production
using satellite imagery - channel migration rates calculated as 23% quicker than in areas that still remained vegetated
what research suggests afforestation is not effective?
Buechel et al (2022)
used uk land simulator to model the effects of large scale afforestation in Great Britain
found that whilst afforestation actively increases channel stability the growth in vegetation may also reduce water availability (due to increased interception and transpiration)
concern in drier areas where water is already a limited resource
Research onto significance of tree species in reforestation-
Qian et al (2024)
found that effective tree planting is also dependent on the three species planted
using native tree species increases soil nutrition and stabilises river banks for longer periods of time than non-native species
Name of study that discusses the effect of animal extirpation from fluvial landscapes?
Beschta and Ripple (2006)
explain the Beschta and Ripple (2006) wolves study
removal of wolves from the Gallatin River basin in early 1900s
Grey wolves hunted and trapped and poisoned = leaving elk population to rise without predation
elk roam river banks decrease vegetation coverage - specifically willow trees
willow trees provide stability for river channels = roughness of above ground stems reduces water velocities and increases deposition also root systems are deep
acceleration of erosion has led to channel widening, incision and avulsion
also decreased hydrological connectivity
study on repatriation of salmon into habitat?
MacDuff and Bauer (2018)
explain MacDuff and Bauer (2018) study?
highlighted that repatriation of species back into habitat is not as simple as just putting them back - prior reconstruction of the river to pre- anthropogenic conditions needed
Study of salmon in Lower Vernon Creek BC , Canada
Due to construction of McIntyre Dam prevented the movement of fish between mainstream lakes and tributaries
saw 90% decrease in spawning
modelling found that only a small fraction of the river is actually viable for reintroduction of salmon as bed material changed size - now too heavy for salmon to move during nesting and water velocity too fast
re-meandering to slow water velocity and control sediment size needed
Study to support the effects of dams on river geomorphology -
Skalak et al 2013
River damming has increased the mean residence time of river waters from 16 to 47 days and increased the volume of water by more than 700%
damming has increased voume of water by what percentage
700%
damming has increased mean residence time of river water from _____ to ______
16 to 47 days
Dams effect on river form
- prevent flow of sediment causing accumulation of material upstream and sediment starvation downstream
- downstream areas experience heightened rates of erosion resulting in channel incision
erosion increased further by straightening of channel causing higher river velocity