1 / 17

Flooding

Flooding. Causes of Flooding. Too much rain: Lots of rain over short period (flash floods) Continued rain over long periods Rain on melting snow Dam failure Hurricanes (sea water floods land). Floodplains.

wylie
Télécharger la présentation

Flooding

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Flooding

  2. Causes of Flooding • Too much rain: • Lots of rain over short period (flash floods) • Continued rain over long periods • Rain on melting snow • Dam failure • Hurricanes (sea water floods land)

  3. Floodplains • Floodplain – flat areas directly adjacent to streams that is periodically covered with water.

  4. Floodplains • Importance: • Serve as natural storage area for flood waters • Flat, fertile land (floods deposit nutrient-rich sediment) • Wetland ecosystems

  5. Floodplain Construction • Over time, meandering widens a stream valley. • Floodplain is formed by shifting point bar deposits. • Note: point bar deposits can be mined for sand and gravel. Fig. 16.21

  6. Floodplain Construction • Floodplains are also constructed by overbank deposits. • water overflows channel onto floodplain • velocity decreases, sed. deposited (sand, silt, clay) Fig. 16.23

  7. Floodplain Construction • Natural levees are the highest point on a floodplain. That's why the French Quarter wasn't flooded during Katrina.

  8. Floodplain Destruction • Fine-grained overbank sediments are deposited on floodplains during a flood. Fig. 16.23

  9. Floodplain Destruction • Flooding is inevitable. • If we choose to live on floodplains, we must be prepared to deal with the consequences. Fig. 16.26

  10. Should the government restrict development in floodplains? • If not, who should pay for reconstruction when homes/buildings in floodplains are damaged or destroyed?

  11. Human Impacts on Streams • Land use changes: • Natural conditions, high infiltration, low runoff • Urban/agriculture, lower infiltration, higher runoff • Human activities tend to increase runoff.

  12. Human Impacts on Streams • Natural – water stored below ground, slowly released to streams • Urban/ag. – runoff increases stream discharge during storms. Fig. 16.30

  13. Flood "Control" • Flooding cannot be prevented and is a common geologic process. • We can only minimize the damage caused by flooding. • Levees (keeps water in the channel) • Detention basins and dams (store flood water)

  14. Levees failed Levees held Flood "Control" • A levee is an artificial wall that keeps water in the stream channel. • Increased water height can cause more damage when levees fail.

  15. Flood "Control" • Detention basins temporarily store water away from streams. • Required drainage control for new developments.

  16. Flood "Control" • Detention basins often double as open spaces.

  17. Flood "Control" • Tipton Trails, Bloomington – artificial meanders and lakes detain water.

More Related