Imagine a wall of water taller than a two-storey house crashing onto the shore—that's a storm surge, and it is just the beginning of a tropical storm's devastation.
Primary effects are the immediate impacts of strong winds, heavy rainfall, and storm surges occurring during or right after the storm. Analyzing these impacts requires looking at both the human and environmental damage. For people, 90% of deaths in tropical storms are caused by drowning due to storm surges. Furthermore, sustained winds exceeding 119 km/h (up to 315 km/h) destroy vital infrastructure, including transport networks, power lines, and sewage systems. Environmentally, these high winds uproot trees, shatter coral reefs, and destroy mangrove forests, while torrential rainfall (often 400–500 mm) leads to immediate flash flooding.
Secondary effects are the indirect impacts that occur later (hours, days, or weeks) as a consequence of the primary effects. For human populations, stagnant floodwater breeds mosquitoes, causing malaria and dengue, while contaminated water leads to waterborne diseases like cholera and dysentery. Economically, the destruction of fishing boats or cash crops leads to long-term unemployment and poverty. Environmentally, saltwater from storm surges contaminates agricultural soil with salt (salinity), making it unusable for years. Additionally, heavy rain on saturated ground causes landslides that permanently alter terrain and block aid routes.
When a Category 5 storm hits, how do you rebuild a city where 90% of the buildings have been flattened? In 2013, Typhoon Haiyan struck the Philippines with sustained winds of 315 km/h and a 5m–6m storm surge, requiring both massive immediate and long-term responses.
The primary effects were devastating: at least 6,300 people died, 1.1 million homes were damaged, and 90% of Tacloban City was destroyed. Environmentally, 33 million coconut trees were uprooted and 8,568 hectares of mangroves were damaged. Secondary effects included an estimated 13–14 billion US dollars in economic loss as 6 million people lost income, and an 800,000-liter oil spill that killed 10 hectares of mangrove forest.
Immediate responses are actions taken in the hours and days after a hazard. The Philippine government successfully declared a "State of National Calamity" to control prices, and evacuated 800,000 people to 1,200 centres. International aid was highly effective: the US sent the USS George Washington (with 13,000 personnel), the UK sent HMS Daring, and over $475 million was pledged. However, the response had failures; the UN admitted aid took up to 5 days to reach some areas, leading to looting in Tacloban.
Long-term responses are actions taken weeks or years later to restore the community and increase resilience. Livelihood recovery was successful; Oxfam replaced 30,000 destroyed fishing boats, and UNDP "Cash for Work" programs paid survivors to clear debris. Environmental recovery was also effective, with 30,000 mangrove seedlings planted in Tacloban. Conversely, structural reconstruction struggled. The government's Build Back Better scheme aimed to upgrade buildings to withstand future storms, but by 2016, only 1% of the 205,000 planned homes had been built.
Overall Judgement: When evaluating the response to Typhoon Haiyan, it is clear that while immediate international aid and long-term livelihood recovery (like replacing fishing boats) were highly successful in preventing further humanitarian disaster, the overall response was undermined by logistical delays in the first 5 days and the severe failure of the Build Back Better structural reconstruction. Therefore, the response was only partially effective, demonstrating that while NEEs can mobilise effective community and international support, large-scale structural resilience remains a significant challenge.
How did Bangladesh manage to reduce cyclone death tolls from 500,000 in 1970 to just 4,000 in 2010? The answer lies in monitoring, prediction, protection, and planning.
Monitoring is the continuous observation of atmospheric conditions, while prediction forecasts when and where a hazard will strike. Satellites monitor cloud formations, and "Hurricane Hunter" aircraft drop dropsondes into the storm's eye to record pressure and wind speed. Ocean buoys measure Sea Surface Temperature (SST), as storms require at least 27°C to form. This technology allows the National Hurricane Centre to create a 5-day probable track. This early tracking allows authorities to issue a Hurricane Warning (conditions expected within 36 hours), enabling early evacuation and thereby reducing mortality.
Protection involves physical actions or structures to reduce impact. In Bangladesh, nearly 2,000 cyclone shelters have been built on stilts with reinforced concrete and shutters. Coastal areas use 3–8m high sea walls and levees. These physical barriers block storm surges and resist high winds, providing the physical resistance needed to lower damage to property and prevent drowning.
Planning involves actions to enable community response. Strategies include hazard mapping to restrict development in high-risk coastal zones, and warning systems (e.g., using bicycles and loudspeakers in remote Bangladesh villages). Educating the public ensures that when a storm hits, people know evacuation routes. However, planning can fail even in wealthy countries; during Hurricane Katrina (2005) in the USA, 1.7 million people were evacuated, but 30,000 vulnerable residents were sheltered in the Louisiana Superdome without adequate food or sanitation, leading to a humanitarian crisis.
Students often list 'flooding' generically as a secondary effect. AQA mark schemes generally treat coastal flooding from storm surges as a primary effect, while the outbreak of disease resulting from that stagnant water is secondary.
When the command word is 'Analyze' for effects, ensure you explicitly link the physical cause (e.g., 315 km/h winds) to the human or environmental result (e.g., homelessness or habitat loss).
In 9-mark evaluation questions, use specific names (e.g., Tacloban, HMS Daring) and exact figures (e.g., 6,300 deaths, $13 billion loss) to reach the highest marking band (Level 3). Always conclude an 'Evaluate' question with a clear overall judgement.
Do not confuse prediction with planning. Evacuation drills and hazard mapping are planning; using satellites and dropsondes is monitoring/prediction.
Primary effects
The immediate impacts of strong winds, heavy rainfall, and storm surges occurring during or right after the storm.
Secondary effects
The indirect impacts that occur later (hours, days, or weeks) as a consequence of the primary effects.
Storm surge
A temporary rise in sea level caused by low atmospheric pressure and high winds pushing water onto land.
Waterborne diseases
Illnesses such as cholera, typhoid, and dysentery caused by drinking water contaminated by floodwater or sewage.
Immediate responses
Actions taken in the hours and days after a hazard, such as search and rescue and providing basic necessities.
Long-term responses
Actions taken weeks, months, or years later to restore the community, rebuild infrastructure, and increase resilience.
Build Back Better
A recovery strategy ensuring new infrastructure is reconstructed to a higher standard of resilience than the original.
Monitoring
The continuous observation of atmospheric conditions using satellites and aircraft to detect and track a storm.
Prediction
Forecasting exactly when and where a hazard will strike using computer models and historical data.
Dropsondes
Instruments dropped from aircraft to record air pressure, temperature, and wind speed inside the eye of a storm.
Sea Surface Temperature (SST)
The temperature of the top layer of the ocean, which must be at least 27°C for a tropical storm to form and maintain energy.
Protection
Physical actions or structures, such as sea walls and cyclone shelters, designed to reduce the physical impact of a hazard.
Planning
Actions and strategies to enable community preparedness, such as evacuation routes, hazard mapping, and emergency drills.
Hazard mapping
The process of identifying areas at high risk of natural hazards to restrict development in those vulnerable coastal zones.
Put your knowledge into practice — try past paper questions for Geography
Primary effects
The immediate impacts of strong winds, heavy rainfall, and storm surges occurring during or right after the storm.
Secondary effects
The indirect impacts that occur later (hours, days, or weeks) as a consequence of the primary effects.
Storm surge
A temporary rise in sea level caused by low atmospheric pressure and high winds pushing water onto land.
Waterborne diseases
Illnesses such as cholera, typhoid, and dysentery caused by drinking water contaminated by floodwater or sewage.
Immediate responses
Actions taken in the hours and days after a hazard, such as search and rescue and providing basic necessities.
Long-term responses
Actions taken weeks, months, or years later to restore the community, rebuild infrastructure, and increase resilience.
Build Back Better
A recovery strategy ensuring new infrastructure is reconstructed to a higher standard of resilience than the original.
Monitoring
The continuous observation of atmospheric conditions using satellites and aircraft to detect and track a storm.
Prediction
Forecasting exactly when and where a hazard will strike using computer models and historical data.
Dropsondes
Instruments dropped from aircraft to record air pressure, temperature, and wind speed inside the eye of a storm.
Sea Surface Temperature (SST)
The temperature of the top layer of the ocean, which must be at least 27°C for a tropical storm to form and maintain energy.
Protection
Physical actions or structures, such as sea walls and cyclone shelters, designed to reduce the physical impact of a hazard.
Planning
Actions and strategies to enable community preparedness, such as evacuation routes, hazard mapping, and emergency drills.
Hazard mapping
The process of identifying areas at high risk of natural hazards to restrict development in those vulnerable coastal zones.