Landscapes, Hazards, and Human Impacts
Landscapes and Their Formation
A landscape is what we perceive of a territory that has been modeled by natural processes and human activities.
Natural Hazards and Environmental Impacts
Natural hazards refer to the probability that a natural process may inflict damage on people and their property within a given landscape.
Environmental impacts are the effects, both positive and negative, that human actions have on the landscape.
Landscape Types
Landscapes can be broadly categorized into: natural landscapes, rural landscapes, and urban landscapes.
Water Systems: Streams and Rivers
Streams and Their Characteristics
Surface runoff consists of water that cannot be absorbed by the ground and moves quickly across the surface. Wild waters are those without a fixed channel.
Streams are irregular watercourses that flow through a small, fixed channel with a steep gradient.
Parts of a stream: A stream typically includes a catchment area, a drainage channel, and an alluvial fan.
Stream-Related Landforms
- Ravines: Deep depressions with steep slopes.
- Ramblas: Streambeds formed by highly irregular streams.
- Gullies: Deep grooves carved by streams in areas of soft, inconsistent rock.
- Badlands: Clay-rich landscapes with numerous gullies.
Rivers and Their Features
Rivers are streams that flow through a fixed, larger bed, and have a longer course than streams. A river has three sections: the upper course, middle course, and lower course.
River-Related Landforms
- Sedimentation:
- Vegas: Plains that form at the bottom of river valleys.
- Deltas: Landforms created when large amounts of sediment are deposited at a river’s mouth.
River-Related Risks
Flood prevention measures: These include building dams, reforestation, avoiding human settlements in flood-prone areas, cleaning streambeds, and constructing channels for redirection.
Groundwater and Aquifers
Groundwater: Water that infiltrates the ground and moves beneath the surface.
Aquifer: A porous rock formation where all cracks and pores are saturated with infiltrated water.
Impacts on Groundwater
The primary impact on groundwater is pollution. Contamination occurs through the infiltration of sewage, agricultural fertilizers, and water from the washing of minerals.
Coastal Processes and Landforms
Littoral Forms and Processes
- Abrasion:
- Cliffs: High, steep coastal walls.
- Abrasion platforms: Surfaces that slope gently towards the sea.
- Caves, arches, and stacks: Formations that originate in coastal rocks with varying resistance to erosion.
- Transport and Sedimentation:
- Beaches: Accumulations of gravel and sand.
- Barrier islands: Sandbanks arranged parallel to the coastline.
- Tombolos: Landforms connecting islands near the coast.
- Spits: Elongated deposits of sand and gravel.
- Lagoons: Bodies of water formed when a spit closes off a bay.
- Wetlands: Marshy areas influenced by tides.
Coastal Hazards
Coastal hazards include hurricanes, storms, tsunamis, waterspouts, and the collapse of buildings.
Coastal Impacts
Coastal impacts include oil spills, dumping of debris, increased sedimentation (altering coastal dynamics), and the salinization of aquifers.
Glaciers and Their Impact
Glacier: A huge mass of ice that can slide due to the slope and shape of the terrain. There are two main types: ice sheets and valley glaciers.
Structure of a Valley Glacier
- Cirque: A hollow where snow accumulates, compacts, and turns into ice.
- Glacial tongue: The part of the glacier that moves slowly downhill.
- Moraines: Collections of materials deposited at the front, bottom, and sides of the glacier.
Glacier-Related Risks
Risks associated with glaciers include avalanches and falling ice blocks.
Impacts of Glaciers
The main impacts on glaciers are pollution and climate change.
Wind Erosion and Sedimentation
Wind:
- Erosion:
- Abrasion: The weathering of rocks exposed to the impact of wind-carried particles.
- Deflation: The mobilization of fine particles from the ground.
- Transportation: Wind carries both large and small fragments.
- Sedimentation: Materials are moved by gravity and streams, including sand and finer particles.