Hard engineering Flashcards
Dams What are they? How does it work? Positives? Negatives? Examples?
They are huge walls built across rivers with a reservoir formed behind (artificial lake)
Flood water is caught by the dam, preventing flooding downstream. the water is then released at a steady flow throughout the year
Flood prevention
Production of electricity using HEP
Reservoir prodiges water for irrigation and used for recreational activities e.g. sailing
Reservoir created behind the dam floods the area, displacing, destroying farmland, disturbing wildlife
Traps sediment behind the dam, increased erosion
Dam failure
Hoover Dam, Lake mead formed behind, vital source of water in Las Vagas
3 Gorges dam China
Channel Modification What are they? How does it work? Positives? Negatives? Examples?
Channels are modified to make them more efficient and able to transport water quickly
Meanders can be removed by building artificial cut throughs, or channels can be dredged to make it deeper and improve discharge capacity, shape + roundness building artificial smooth banks (concrete) or removing large boulders
Reduces flooding as the water will flow downstream quicker
Improves river navigation
Increased risk of flooding and erosional rates downstream
Disturbing wildlife habitats
Costly
River Derwent between Sherburn and Brompton in the vale of Pickering straightened throughout the 1800’s
Diversion channels What are they? How does it work? Positives? Negatives? Examples?
Artificial river channels that take the water elsewhere if the water level is too high
Water is normally diverted around an important area or to another river
Prevents flooding as river discharge is reduced
Spillways have gates which open and close to control the release of water
Where a diverted river joins another river, discharge increases, flooding could occur below that point
If spillways are overwhelmed, water will flood areas not used to flooding
Town of high river, southern Alberts, Canada
Levee and flood plain modification What are they? How does it work? Positives? Negatives? Examples?
Artificial levees or embankments built along the sides of a river to stop it being overwhelmed so easily
They allow the river to hold a greater discharge and floodplain to be built on
The height of the floodplain can be raised by dumping material on it
Stops overflowing so easily
Allows the river to hold a greater discharge and flood plains to be built on
Expensive- levees
If breached, can cause worse floods
Prevent water from draining back into a river
New Orleans, surrounded by artificial levees to protect the Mississippi River from flooding
Collapsed during the hurricane katrina causing devastating floods
What is a case study for hard engineering?
The 3 gorges dam
What are the characteristics of the 3 gorges dam?
2.3km long Completed in 2006 Built across the Yangtze river Generates electricity from HEP for central and Eastern China e.g. Shanghai Huge Reservoir- 660km long, 1km wide 25 billion pounds to build
What are the positives of the 3 Gorges dam?
Social- Important symbol for China’s modernisation
Environmental- Burning 40 million tonnes of coal per year will be replaced by clean, environmentally friendly HEP
Environmental- Reduces CO2 emissions to the atmosphere by 120 million tonnes a year
Social- 15 million protected from flooding
Economic- Creates employment in the area
What are the negatives of the 3 Gorges dam?
Social- Reservoir flooded the homes of more than 1 million people
Environmental- silt trapped behind the dam, making farmland less fertile
Environmental- Habitats of rare and endangered animals such as Baji are disturbed
What is hard engineering?
Hard engineering defenses are man-made structures made to act against nature
