Welcome to Chapter 6.5: The Impacts of Natural Hazards!

Hi future Environmental Managers! This chapter is incredibly important. We've looked at *what* natural hazards are (earthquakes, cyclones, floods, droughts) and *why* they happen. Now, we dive into the heartbreaking reality: the consequences these events have on people and the planet.

Understanding these impacts is the first step toward managing them effectively, which is what the rest of this section is all about. Don't worry, we'll break down the devastating effects into clear categories so you can analyze them easily in the exam!

The Three Major Categories of Impact (S.E.E.)

When discussing any natural hazard's impact, it's helpful to categorize the effects into three main areas. This framework (S.E.E.) is your secret weapon for extended response questions!

  • Social Impacts: Effects on people, communities, health, and daily life (e.g., loss of life, trauma).
  • Economic Impacts: Effects on money, jobs, infrastructure, and financial stability (e.g., damage costs, loss of crops).
  • Environmental Impacts: Effects on the natural world, ecosystems, and resources (e.g., habitat loss, soil erosion).

6.5.1 Impacts of Tectonic Hazards (Earthquakes, Volcanoes, Tsunamis)

Tectonic hazards, caused by plate movement, tend to be sudden and highly destructive, leading to catastrophic immediate effects.

Social and Human Impacts

  • Loss of Life and Trauma: This is the most immediate and severe impact. Earthquakes can collapse buildings, killing and injuring thousands instantly. Surviving such an event often leads to severe psychological trauma.
  • Water-Related Disease: Damage to sewage systems and water pipes contaminates drinking water supplies. This increases the risk of infectious diseases like typhoid and cholera spreading rapidly amongst displaced populations.
  • Displacement: Many people lose their homes and must seek refuge, sometimes requiring emergency shelter for months.

Economic and Infrastructure Impacts

  • Damage to Buildings and Infrastructure: Roads, bridges, hospitals, power lines, and factories are destroyed or severely damaged. Rebuilding costs billions (a major financial loss).
  • Secondary Hazards (Fire and Landslides):
    • Earthquakes break gas and power lines, leading to widespread fire.
    • Ground shaking can trigger massive landslides, burying entire communities or blocking crucial transport links.
  • Loss of Farmland: Volcanic eruptions can cover productive land with ash, or earthquakes/tsunamis can flood coastal farmland, making it unusable temporarily or permanently.

Environmental Impacts

  • Tsunamis: These massive waves destroy coastal habitats (like coral reefs and mangrove forests) and flood low-lying areas with saltwater, killing crops and delicate ecosystems.
  • Loss of Habitats: Landslides and lava flows destroy natural habitats, leading to localized losses of biodiversity.
Quick Review: Tectonic Impacts

The key word for tectonic impacts is destruction. They cause massive immediate physical damage, followed closely by disease and high financial cost.

6.5.2 Impacts of Atmospheric and Hydrological Hazards (Tropical Cyclones and Flooding)

Tropical cyclones (hurricanes, typhoons, storms) cause their primary damage through extremely high winds, heavy rainfall, and storm surges (a rise in sea level). Flooding is the most common impact for both.

Social and Health Impacts

  • Loss of Life: Primarily caused by drowning during the surge or flash floods.
  • Contamination of Water: Floodwater often mixes with sewage and chemicals. This contamination of drinking water supplies is a huge risk, causing outbreaks of water-related diseases (cholera, dysentery).
  • Damage to Homes: Houses, especially those poorly constructed, are destroyed by wind or water, leading to the need for emergency shelters.

Economic and Livelihood Impacts

  • Loss of Crops and Livestock: Flooding washes away crops that are ready to harvest (loss of immediate food supply) and kills farm animals, leading to financial disaster for farmers and potential food shortages.
  • Damage to Infrastructure: Similar to tectonic events, roads and power grids are damaged, halting transport and business operations.
  • Financial Losses: The cost of damage and clean-up leads to huge financial losses for local communities and the government.

Environmental Impacts

  • Loss of Habitats: Coastal ecosystems (like mangroves) may be ripped up by storm surges.
  • Soil Erosion: Intense rainfall washes away the topsoil, reducing future agricultural fertility.
Did You Know?

When a tropical cyclone hits, the coastal flooding caused by the storm surge is often more deadly than the wind itself!

6.5.3 Impacts of Drought

Unlike the rapid destruction caused by floods or earthquakes, drought is a slow, creeping disaster caused by a prolonged lack of rain. Its impacts often worsen over many years.

Social and Human Impacts

  • Starvation and Malnutrition: The most serious social impact. Drought causes a decline in crop yields (or total crop failure), leading to widespread food scarcity, particularly in Less Economically Developed Countries (LEDCs).
  • Water Sources Dry Up: Reservoirs, wells, and rivers become empty. People must walk huge distances to find water, disrupting education and work.
  • Displacement of People: As land becomes unproductive, farmers and communities are forced to leave their homes in search of water and food (environmental refugees).

Economic Impacts

  • Loss of Income: Farmers lose their only source of income when crops fail, leading to widespread poverty.
  • Death of Livestock: Farm animals die due to lack of water and grazing land, crippling the pastoral economy.

Environmental Impacts (Focus Area!)

  • Death of Organisms: Widespread death of plants and animals due to water stress.
  • Increased Soil Erosion: Dry, loose soil is easily picked up and blown away by the wind (wind erosion), especially if vegetation cover is lost.
  • Desertification: This is the process where fertile land turns into desert, often caused or accelerated by drought and poor management. This greatly reduces the amount of land available for future farming.
  • Decrease in Air Quality: More dust in the air due to dry conditions and exposed soil can cause respiratory problems.
  • Increased Risk of Wildfires: Extremely dry vegetation acts as perfect fuel, making the risk of catastrophic fires much higher.
Analogy for Desertification

Imagine trying to plant seeds in dry sand—it won't hold water or nutrients. Drought turns soil into this kind of dead material. When soil erosion and drought combine, they accelerate the land's change into a desert-like state: desertification.

Summary Table: Key Impacts

Use this table to quickly review the specific impacts you must be able to recall for the exam (Syllabus 6.5).

Hazard Type: Tectonic Events (Earthquakes, Tsunamis)

  • Damage to buildings/infrastructure
  • Fire/Landslides/Tsunamis
  • Loss of life and trauma
  • Water-related disease (from contamination)
  • Financial losses

Hazard Type: Flooding / Tropical Cyclones

  • Loss of life, livestock, and crops
  • Damage to buildings/infrastructure
  • Contamination of drinking water supplies
  • Water-related disease (cholera, typhoid)

Hazard Type: Drought

  • Decline in crop yields / Starvation
  • Water sources dry up
  • Increased soil erosion and desertification
  • Decrease in air quality (dust)
  • Increased risk of wildfires

Keep practicing categorizing these impacts—it will prepare you perfectly for the management strategies in the next section! Good luck!