We study HEP & The Three Gorges Damn case study to answer the below question on Human Interaction with Surface Processes. This question appears regularly. You may have an opportunity to answer HEP questions in Economic Geography also. You could be asked to select sites for renewable energy sources on OS Maps.
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History of Yangtze Floods - Before the damn construction
1931 China Floods:
Catastrophic flooding followed three years of drought, affecting the Yangtze and Yellow Rivers.
Considered the worst non-pandemic disaster of the century, indirectly causing millions of deaths.
1935 Yangtze Flood:
Occurred during a period of frequent flooding, famine, and social unrest in China.
Estimated death toll: 145,000, with millions displaced.
Survivors faced challenges such as displacement, injuries, property loss, food shortages, and famine.
Happened before flood defences could recover from the 1931 disaster, overwhelming drainage reservoirs and floodwater channels.
Hydroelectric Power (HEP): Positives and Negatives
Positives of HEP
Renewable Energy Source: This means that it uses water as its primary resource, which is replenished naturally through the water cycle, ensuring sustainability.
This means that countries relying on HEP reduce their dependence on fossil fuels, lowering greenhouse gas emissions.Flood Control and Irrigation: This means that dams can regulate river flow, reducing the risk of downstream flooding in vulnerable areas.
This means that reservoirs created by dams provide a stable water supply for agriculture and human consumption.Economic Development: This means that the generation of electricity can power industries and provide energy to rural areas, boosting economic activity.
This means that infrastructure associated with HEP projects, such as roads and bridges, benefits local communities.
Negatives of HEP
Environmental Damage: This means that the flooding of large areas for reservoirs destroys ecosystems, displaces wildlife, and leads to biodiversity loss.
This means that sedimentation behind dams affects water quality and alters downstream habitats.Displacement of People: This means that large-scale dam projects force communities to relocate, often losing their homes, farmland, and cultural heritage.
This means that resettlement efforts are often inadequate, leading to long-term social issues.High Construction Costs: This means that HEP projects require significant financial investment, which can strain government budgets.
This means that developing nations might take on debt to build dams, potentially hindering other development priorities.
Three Gorges Dam: Positives and Negatives
Positives
Renewable Energy Generation:
The Three Gorges Dam generates 22,500 MW of power, making it the largest HEP station in the world.
This means that it provides clean energy to millions of people, reducing China’s reliance on coal and lowering CO₂ emissions.
This means that it supports China’s push toward sustainable development.
Flood Control:
The dam reduces the risk of catastrophic flooding on the Yangtze River, which has historically caused thousands of deaths.
This means that it protects millions of people and agricultural land downstream.
This means that economic activity in the region is safeguarded from the impacts of frequent flooding.
Economic Benefits:
The dam boosts trade and commerce by improving navigation along the Yangtze River.
This means that larger ships can access inland ports, supporting regional development and trade.
This means that the project has created thousands of jobs in construction, operation, and tourism.
Negatives
Displacement:
Over 1.3 million people were displaced to make way for the dam and its reservoir.
This means that communities lost their homes, farmland, and cultural heritage, leading to social and economic challenges.
This means that resettlement efforts were criticised for being poorly planned and underfunded.
Environmental Impact:
The dam flooded 632 km² of land, submerging ecosystems and historical sites.
This means that biodiversity in the area was significantly reduced, with species like the Chinese river dolphin pushed to extinction.
This means that sediment trapped behind the dam has altered downstream habitats and increased erosion.
Seismic Risks:
The weight of the reservoir water has increased pressure on fault lines in the region.
This means that the area is now more susceptible to landslides and earthquakes.
This means that these risks could undermine the long-term stability of the dam.
Does the damn actually prevent flooding?
Three Gorges Dam – Flood Control Analysis
Chinese Government’s 1992 Proposal:
Primary goal: Prevent flooding, not power generation.
Mechanism: Trap rainwater in the reservoir and control its release through sluice gates.
Flood Storage Capacity:
The reservoir creates 22 billion cubic meters of storage space, equivalent to 9 million Olympic swimming pools.
This is only about 9% of the water volume during extreme floods (e.g., "once-a-century" floods).
Criticisms of Flood Control:
During severe floods, the dam cannot handle the vast volume of water (244 billion cubic meters can pass through in two months).
It has been likened it to using a small cup for a big tub of water.
The dam releases water during heavy rains, which has been criticised for potentially worsening downstream flooding.
Evidence from Recent Events:
Poyang Lake and downstream areas experienced record-breaking flood levels despite the dam’s operation.
The 1998 flood record was surpassed, with severe downstream impacts.
Academic Opinions:
The dam cannot prevent severe floods, as evidenced by the highest water levels ever recorded.
Studies show the reservoir is too small to reduce downstream discharge significantly during extreme floods but helps in normal years.
Broader Context:
The dam alone cannot solve the Yangtze River's flooding issues.
While it reduces upstream flood intensity, it cannot address intense rainfall in middle and lower reaches or tributaries outside its basin.
Conclusion:
Top academics and geologists have found that The Three Gorges Dam helps alleviate flooding under normal conditions but is insufficient to manage severe floods or downstream rainfall.
Source of Information: https://edition.cnn.com/style/article/china-three-gorges-dam-intl-hnk-dst/index.html
Human interaction with river processes can have a significant impact
(S) The Three Gorges Dam on the Yangtze River in China is a prime example.
(D) It influences erosion, deposition, and flooding.
(SE) This demonstrates the large-scale impact of human engineering on river systems.
The Yangtze River supports 350 million people in the valley and provides 70% of China's rice
(S) However, flooding has been a historical problem.
(D) Since 1860, over five million people have died from Yangtze River floods.
(SE) The Three Gorges Dam was built to reduce this devastating impact.
Flooding occurs after monsoons and snowmelt, raising water levels
(S) This flooding posed serious risks to lives and agriculture.
(D) The construction of the Three Gorges Dam aimed to control this.
(SE) The dam has successfully reduced the frequency and severity of floods in the region.
The dam, built between 1993 and 2008, cost €20 billion
(S) It spans 2.3 km and is 185 m high, making it the largest dam in the world.
(D) It is crucial for flood control and energy production.
(SE) The dam has become a symbol of China's advancements in infrastructure.
The dam controls the river by creating a reservoir
(S) This slows water flow, prevents flooding in summer, and eliminates shallow waters in winter.
(D) It also improved river transport.
(SE) The reservoir helps manage water levels throughout the year.
Hydroelectric power from the dam reduces China's reliance on coal
(S) This has significantly lowered carbon emissions.
(D) The renewable energy generated is environmentally friendly and cost-effective.
(SE) The dam is a major contributor to China’s clean energy efforts.
The dam displaced nearly two million people
(S) Flooded towns forced people to relocate, leading to deforestation.
(D) Deforestation has increased the risk of landslides.
(SE) Social and environmental challenges have arisen due to these relocations.
Landslides add sediment to the river, impacting deposition
(S) If unmanaged, this sediment can accumulate behind the dam, reducing its efficiency.
(D) It can also decrease the dam’s storage capacity.
(SE) This poses long-term maintenance issues for the dam.
The dam is in an earthquake zone, which increases seismic risks
(S) The weight of the water and dam structure could trigger earthquakes.
(D) This poses long-term threats to the region.
(SE) Earthquake risks are a concern for the safety and stability of the dam.
The dam has enhanced tourism in the area
(S) Its massive size and scenic surroundings attract tourists, boosting the local economy.
(D) Tourism is an additional economic benefit of the dam.
(SE) The dam has become a major tourist destination in China.
Deeper water created by the dam improves river transport
(S) Ships can now navigate year-round, supporting trade and the local economy.
(D) This has made the river more efficient for transporting goods.
(SE) The dam has enhanced the region's logistical capabilities.
The reservoir, spanning 600 km², has altered ecosystems
(S) While some species have adapted, others have declined due to changes in water quality.
(D) This has affected biodiversity in the region.
(SE) The environmental impact of the dam continues to evolve.
Hydroelectric power reduces China’s fossil fuel dependence
(S) The clean energy generated by the dam offsets millions of tons of CO₂ emissions annually.
(D) It supports China’s carbon reduction goals.
(SE) The dam plays a key role in China’s efforts to combat climate change.
An Irish example of hydroelectric power is the Ardnacrusha station on the River Shannon
(S) Built in the 1920s, it provides a significant portion of Ireland’s electricity.
(D) It also controls river flow and reduces flood risk.
(SE) This example demonstrates the benefits of hydropower in flood management and energy generation.
Condensed for Timed Exam
Impact of Human Engineering
The Three Gorges Dam on the Yangtze River in China significantly impacts river processes, influencing erosion, deposition, and flooding, demonstrating the large-scale effects of human engineering on river systems.
2.
Support for Population and Agriculture
The Yangtze River supports 350 million people, providing 70% of China's rice, but historical flooding has claimed over five million lives since 1860. The Three Gorges Dam was built to mitigate these devastating impacts.
3.
Flood Control
Flooding occurs after monsoons and snowmelt, posing risks to lives and agriculture. The construction of the Three Gorges Dam successfully reduces the frequency and severity of floods in the region.
4.
Cost and Scale of Construction
Built between 1993 and 2008 at a cost of €20 billion, the dam spans 2.3 km and stands 185 m high, making it the largest dam globally. It plays a crucial role in flood control and energy production, symbolizing China's infrastructure advancements.
5.
Reservoir Management
The dam creates a reservoir that slows water flow, prevents summer flooding, and eliminates shallow winter waters. This reservoir also improves river transport and helps manage water levels year-round.
6.
Reduction of Carbon Emissions
Hydroelectric power generated from the dam reduces China's reliance on coal, significantly lowering carbon emissions. The renewable energy produced supports China's clean energy initiatives.
7.
Social and Environmental Challenges
The dam displaced nearly two million people, flooding towns and leading to deforestation, which increases the risk of landslides. These relocations have created social and environmental challenges.
8.
Sediment Management
Landslides add sediment to the river, which can accumulate behind the dam, reducing efficiency and storage capacity, posing long-term maintenance issues.
9.
Seismic Risks
Located in an earthquake zone, the dam's weight and structure could trigger earthquakes, presenting long-term safety threats to the region.
10.
Tourism Enhancement
The dam's massive size and scenic surroundings attract tourists, boosting the local economy and establishing it as a major tourist destination in China.
11.
Improved River Transport
Deeper water created by the dam allows for year-round navigation, supporting trade and enhancing the local economy, improving logistical capabilities.
12.
Ecosystem Alterations
The reservoir, spanning 600 km², has altered ecosystems, affecting biodiversity as some species adapt while others decline due to changes in water quality.
13.
Fossil Fuel Dependence
The hydroelectric power generated by the dam offsets millions of tons of CO₂ emissions annually, supporting China’s carbon reduction goals and playing a key role in combating climate change.
14.
Irish Example of Hydropower
The Ardnacrusha station on the River Shannon, built in the 1920s, provides significant electricity for Ireland and controls river flow to reduce flood risk, exemplifying the benefits of hydropower in flood management and energy generation.
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