1 / 15

Flood (and drought) prediction

Flood (and drought) prediction. ERS 482/682 Small Watershed Hydrology. Floodplain management. Any action to reduce future flood damages Flood control Structures to control floods May reduce flood frequencies at certain locations May increase flood frequencies at other locations

rivka
Download Presentation

Flood (and drought) prediction

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. Flood (and drought) prediction ERS 482/682 Small Watershed Hydrology

  2. Floodplain management • Any action to reduce future flood damages • Flood control • Structures to control floods • May reduce flood frequencies at certain locations • May increase flood frequencies at other locations • Tend to lead to increased development  bigger floods

  3. Figure 11-8: Dunne and Leopold (1978)

  4. Floodplain management • Any action to reduce future flood damages • Flood control • Structures to control floods • May reduce flood frequencies at certain locations • May increase flood frequencies at other locations • Tend to lead to increased development  bigger floods • Damage control • Policies to reduce flood damage

  5. Figure 11-6: Dunne and Leopold (1978)

  6. Figure 16.37: Viessman and Lewis (1997)

  7. Figure 11-29: Dunne and Leopold (1978)

  8. Figure 10-29: Dingman (2002)

  9. Flood prediction • Statistical analysis of historical streamflows • Construct annual series of peak flows • Calculate exceedence probability • Non-parametric • Parametric • Normal distribution • Log-normal distribution • Gamma (Pearson Type III) distribution • Gumbel’s extremal distribution • Predict flows for extreme events

  10. Flood prediction at ungaged sites • Flood magnitude-frequency relations • Relate magnitude of floods to measurable basin characteristics (see example in Box 10-9) • USGS has relationships for all 50 states • Apply rainfall-runoff models • Rational method • SCS Curve Number method • Etc. ASSUMPTION:Ungaged basin isthe same asgaged basin

  11. Drought definitions • Low flows • Frequency analysis with minimum flows • Annual minimum flows averaged over consecutive days • High exceedence probability (e.g., 95%) • Example: 7Q10 10% probability that the lowest 7-consecutive-day average flow will be less than the 7Q10 value • See Table 10-18

  12. Drought definitions • Extended severe dry periods • Must have duration • Must be a significant departure from normal • Can be defined in terms of • Precipitation • Streamflow • Groundwater level

  13. Define drought threshold severity Figure 10-36: Dingman (2002)

  14. 6 8 5 8 Average = 709 cfs D  5 years

More Related