Natural Hazards, Resources, and Sustainable Development
Water Cycle: (Rainfall, infiltration, evaporation) solar-driven. Oceanic Conveyor Belt: Distributes heat to all the seas of the planet.
Natural Hazards
Floods: A natural phenomenon with the most casualties. Overflowing rivers or streams, especially in the Mediterranean area (wadi, intermittent water courses), cause strong slope erosion.
Landslides: Falling materials due to steep slopes, often caused by heavy rains and earthquakes. Rock type is a significant risk factor.
Earthquakes: Ground vibrations caused by the mobility of lithospheric plates, resulting in earthquakes of great destructive power at plate edges.
Tsunamis: Giant waves caused by sudden deformation of the seabed, often triggered by earthquakes, volcanic eruptions, or submarine avalanches.
Volcanic Eruptions: Volcanoes erupt, launching magma particles at high speed in very hot gas clouds (nuées ardentes). If these fall into river channels, they become mudflows.
Scientists and Hazard Prediction
Meteorologists: Study satellite data to predict rainfall.
Seismologists: Study the Earth’s movement with electronic instruments.
Volcanologists: Develop volcanic hazard maps to inform inhabitants of at-risk areas.
Oceanographers: Develop approaches to localize tsunami hazards.
Hazard Maps: Fundamental tools in planning, used to approve or disapprove activities based on risk assessment.
Resource Consumption and Sustainability
Growing Consumption and Limited Resources: Humans use land resources for building, moving, feeding, and cultural expression.
Population-Carrying Capacity: The maximum number of inhabitants the land can sustain.
Overfishing: Since 1989, catches have reached 100 million tons annually, diminishing fish stocks. Species cannot reproduce fast enough to sustain the catch, leading to potential species disappearance and total depletion of fisheries by 2050.
Deforestation: Vegetation loss leads to soil erosion and desertification. Sustainable forestry practices are needed for wood production.
Energy Sources
Hydroelectric Energy: Water from a river is dammed and channeled through turbines to produce electricity.
Nuclear Energy: Nuclear power plants use enriched plutonium-uranium-235, bombarded with neutrons, to release energy that heats water to steam, driving turbines to generate electricity.
Wind Energy: Modern windmills (wind turbines) convert the motion of blades into electrical energy.
Solar Energy: An inexhaustible source used directly by converting sunlight into electricity via solar panels or as heat in solar thermal power plants.
Hydrogen Energy: Combustion produces water vapor. Two methods: photovoltaic panels decompose H2O into H2 and O2, or nuclear fusion creates miniature suns generating large amounts of energy without radioactive waste.
Sustainable Development
Sustainable Development: Meets the needs of the present generation without compromising the ability of future generations to meet their own needs. This means not exploiting renewable resources faster than their replacement rate and not releasing waste into the environment beyond its absorptive capacity.