Rivers and People Flashcards
Can rivers run north?
Yes
Why are rivers important to society?
- Drinking, washing
- Transportation
- Agriculture (fertilization, irrigation)
- Recreation
- Wildlife habitat
- Electric power
Why are rivers important to agriculture (2 reasons)?
- Rivers provide fertile cropland (flood deposits are
nutrient rich) and water for irrigation - Rivers provide water for irrigation, which is especially important in arid or semi-arid regions
What is a flood?
temporary overflow of a stream onto adjacent lands typically not covered by water
What causes flooding?
3 Main (sometimes related) Causes
- High precipitation
- Saturated ground
- Stream alteration by people
What are the 3 main type of floods?
- rising flood
- flash floods
- wind-driven flood tides
What is a rising flood?
a rising flood which occurs because of heavy prolonged rain or melting snow or both.
What is a flash flood?
flash floods which are characterized by quick rise and fall of flood levels (lots of those around here!).
What are wind-driven flood tides?
wind-driven flood tides that combine wind and tides to flood coastal areas.
What river in the world has killed the most people?
The Yellow River
What are nearly all flood deaths related to?
Auto-related
How can human alteration of river and landscapes affect flooding?
Increases flooding
Why does urbanization change natural flood regime?
- More impenetrable surfaces like concrete and asphalt cause rapid runoff and reduce absorption into ground
- Channelization and human-made levees
What is channelization?
Straightening of stream channel for efficient movement of floodwaters downstream away from urban areas or to drain farmland.
Why are artificial levees built?
To protect property such as croplands, homes, businesses
How are artificial levees both good and bad?
Channelization and artificial levees combined prevent local flooding, BUT cause dramatically increased erosion and flooding DOWNSTREAM
How are urbanized rivers bad?
- Higher floodwaters
* Shorter lag time (less warning)
What are some negative ecological impacts caused by channelization and built levees?
Channelization and built levees also cause negative ecological impacts such as degradation and loss of “riparian” zones (special area between land and river) and wetlands in general
What do wetlands do to river levels?
Wetlands keep river levels normal and purify and filter water
Is alluvium fertile?
Yes, very!
In Egypt, where do the majority of its people live?
95% live within 12 miles of the nile
Why build dams?
They generate electricity
What are some advantages to the Aswan Dam in Egypt?
slide 36
What are some disadvantages to the Aswan Dam in Egypt
- 90,000 Nubians had to be relocated, some as many as 350 mi. from home
- Had to relocate the ancient temple, Abu Simbel
-many other artifacts were lost under water - Sediment deprived delta = erosion, shrinking of delta,
and decreased shrimp harvest in Mediterranean
Slide 41
What is the worlds largest dam? What river is it on?
Three Gorges, China
20 years, $26 billion to construct
Yangtze River
What is some controversy over the Three Gorges Dam?
The reservoir has/will submerge the three world-famous gorges, along with their cultural (villages/cities) and archaeological sites.
Slide 44
What are some advantages to the Three Gorges Dam and dam power in general?
- Cleaner than coal
- May prevent catastrophic flooding (will saves thousands of lives)
- Economic benefit—large ships will be able to reach inland
Dam has 26 generators, EACH similar to medium nuclear reactor
What are some disadvantages to the Three Gorges Dam and dams in general?
- Loss of best farmland and some villages/towns
- Reduced fertilization downstream from silt
- Loss of spectacular scenery, and archaeological sites - Tourism
- Unknown consequences for river flora and fauna
- Pollution from cities upstream, Schistosomiasas
- Economic strain for China in the cost of the project
