Surface 5: Life & Humans as Geomorphic Agents

Biogeomorphology (define + significance)

• the study of the interactions between living organisms and geomorphic processes and landforms

• it highlights the role of plants, animals, and microorganisms in shaping landscapes

Role of beavers in shaping landscapes

building dams:

• create ponds & wetlands

• alter river channels

• influence hydrology & sediment transport

3 types of ecosystem engineers

• Bio-constructors: build new landforms → beavers, corals

• Bio-eroders: wear down landforms → badgers, rabbits

• Bio-protectors: shield landforms from erosion → plants, barnacles

Influence of bio-eroders

displace and deposit large quantities of sediment → mixing, aerating, compacting sediment → changes in soil erodibility and sediment transport rates

2 way feedback: geomorphic engineers & landforms

modify the dynamics of geomorphic processes → causes feedback to animal & plant populations → encourages natural selection → causes changes in biological traits and adjustments in the structure & function of the ecosystem

Topographic signature: short timescales

Over short timescales, biotic processes mediate chemical reactions, disrupt the ground surface, expand and strengthen soil → affecting weathering, soil formation, erosion, slope stability, and river dynamics

Topographic signature: geological timescales

biotic effects less patent but still significant → plants & animals help shape the climate → climate dictates the mechanisms and rates of erosion → constraining topographic evolution

Anthropogeomorphology (define + significance)

• the study of human interactions with geomorphic forms and processes

• highlights the impact of human activities on landscapes and the environment

Anthropocene (define + significance)

• proposed geological epoch characterized by significant human impact on the environment

• emphasizes the role of humans in shaping landscapes and geomorphic processes

Anthroposphere (define)

• comprises parts of the planet made by humans

• chief components by mass are the urban area and rural housing

Proposed anthropocenes

• Industrial Revolution: burning of fossil fuels replaced water power

• The Great Acceleration: when the rate at which humans were altering the world in ways that would leave indelible traces in the future began accelerating → growing human population

3 Types of Human Impact

• Indirect environmental changes → global warming

• Directly modifying geomorphic processes → stripping vegetation cover → increasing soil erosion rates

• Directly creating landforms → excavation & dam building → altering river flows

Geomorphic Footprint

• measures the rate at which humans create new landforms and mobilize sediment

Role of Mining & Construction

moves large amounts of earth materials → creating new landforms → influencing sediment transport & erosion rates

Role of Dam Building

• reduces the amount of sediment carried to coasts

4 Categories of Technogenic (manmade) land

• aggraded → built up deposits

• degraded → artificial induced erosion

• modified → by chemical and mechanical processes

• mixed → complex technogenic profile

Hydrological impacts of aggradation and degradation

• aggradation → relative drop in water table levels

• degradation → artificial rise in water table levels

Types of Human landforms

• Flats → widespread, created when ground is levelled for construction purposes

• Benches → associated with construction or landscaping in urban areas

• Terraces: common features of hillslope agriculture and strip-mined land

Bombturbation

• the impact of explosive munitions upon the landscape

Cities as emerging landforms

• biosphere: deforestation → habitat loss, pollution → spread of invasive species

• atmosphere: urban heat-island effect → increased regional temperatures

• hydrosphere: increased runoff → increased erosion + decline in soil quality

more pronounced in areas of neglect/abandonment

Applied geomorphology (define + benefits)

• application of geomorphological knowledge and techniques to solve societal problems

• e.g. natural hazard mitigation, land-use planning, environmental management