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Human activity in deserts - Coggle Diagram
Human activity in deserts
Urbanisation
Pressure of population growth in semi-arid areas on edges of desert
Growth of cities increases demand for water
Agriculture takes place to provide for cities = reduces further the limited water resources.
Deforestation increases for land and building supplies
Impact varies from LEDC to MEDC
Mining
Deserts often have rich mineral deposits
Minerals - examples are gold, silver, copper, uranium, iron and lead-zinc.
Disturbs habitats and ecosystem
Roads need to be built for operations
Toxic waste - Uranium mining creates a host of radioactive hazards.
Urban areas needed for support facilities and workers
Mining often need waters
Drilling alters the ecology – worse if any oil is spilled.
Tourism
Desert tourism growing.
Egypt – pyramids; Aswan Dam
Desert Safaris in areas such as Qatar
Hoover Dam and Las Vegas
Need to ‘experience something different’
Causes conflict – demand for water; damage to fragile environment; cultural conflicts
Desertification - The process by which productive land changes into desert-like landscape.
Overgrazing and farming – this causes soil to be exposed as less grows on it; exposed soil is at risk from greater erosion
Poor irrigation – this can cause salinity of the soil so reducing what can be grown so soil is exposed and at risk from erosion
Deforestation – less trees mean less protection for soil; no roots to bind the soil; no leaves so less nutrients in soil so less grows; soil exposed
Urbanisation- growth of city puts pressure on water resources and encourages deforestation
Population can also be used for a 5th mark – as this then causes an increase in the above
Climate change – only use if pushed for another mark as often question is focused on more local causes
Solutions to desertification
Aim: to reduce soil erosion
Windbreaks – planting of trees “Great Green Wall”
Drip irrigation
Reduce number of cattle
(Magic) stones – placed around plants
https://www.bbc.com/news/technology-56428984
UAE to use drones to increase rainfall
Case study
Location
• Southern USA – S. California, S. Arizona and into Northern Mexico
• Subtropical desert – located around 32⁰N [know formation of subtropical deserts]
Climate characteristics
• High average annual temperature [15-30 ⁰C] and low rainfall [300mm]
• 2 rainy seasons with short, heavy spells of rain
• Flash floods are frequent - removes any soil that is uncovered
Vegetation features
• Adaptations to climate – know general information from book
• Saguaro cactus [can live for 175 years] Stem – swells when rains,
reduces wind speed, sunken stomata reduce transpiration, shallow roots
• Cacti such as the prickly pear and hedgehog
cacti show many of the adaptations
• Palo Verde is a small drought tolerant tree; loses leaves in dry season, green bark allows photosynthesis
Threats
• Urbanization – growth of cities such as Phoenix, leading to increased infrastructure
• Increasing retirement population: demand for water high for swimming pools and golf courses
• Increasing tourism – Marana: resort town of 30,000
• Overgrazing and off-road vehicles compacting ground and removing vegetation
• Changing ecosystem as non-native plants and animals threaten the area
Consequences
• Mesquite bushes and cottonwood along water courses have died as water has been extracted
• Road construction and pipelines have affected migration routes of animals
• Increasing use of fences, preventing pronghorn antelopes from reaching water supplies
• Increased flood risk as soils compacted and vegetation removed.
• Alien plants such as tamarisk have replaced native cottonwood in many areas
• Water table being lowered due to increasing demand
• Pygmy owl under threat
Solutions
• Development of sustainable tourism, focusing especially on water conservation
• Sonoran Desert Conservation Plan – focusing on wildlife and housing expansion threats
• Areas mapped to produce zones
• Advice given on new homes to make them water and energy efficient
• National Parks [Saguaro National Park] and reserves created [Sonoran Preserve]
