1 / 16

Stream morphology and hydrology

Stream morphology and hydrology. Hydraulic geometry. Typical at a station values (midwestern streams). b = 0.25 f = 0.4 m = 0.35. B = aQ b h = cQ f U = kQ m. Typical downstream values. b = 0.5 f = 0.4 m = 0.1. Hydrology short overview. Stream records Flow duration curves

Download Presentation

Stream morphology and hydrology

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. Stream morphology and hydrology

  2. Hydraulic geometry Typical at a station values (midwestern streams) b = 0.25 f = 0.4 m = 0.35 B = aQb h = cQf U = kQm Typical downstream values b = 0.5 f = 0.4 m = 0.1

  3. Hydrology short overview • Stream records • Flow duration curves • Flood frequency curves • Importance of short-lived (<< 1 day) rare events (“flashiness”)

  4. Example: Anoka discharge record

  5. Flow duration curve

  6. Note: daily Q values do not capture true maxima For small basins (< 100 km^2), 15 min max Q can be ~10x annual daily max Q

  7. Flow duration curve

  8. Flood frequency (return period) Note: Find annual max on water year basis

  9. If gage data are not available… • USGS regional curves: multiple regression of flood frequency on basin area, other variables • Gage analysis: estimation based on discharge records from nearby basins, correcting for basin area • Literature: “prediction in ungaged basins”

  10. USGS regional curves

  11. USGS regional curves

  12. USGS regional curves

  13. USGS regional curves Minnesota Region D: Lorenz et al. USGS 2009-5250 Q1.5 = 0.892 DAREA0.778 SLOPE 0.422 (LAKE+1)-0.29 ROFF1.144 Q2 = 1.58 DAREA0.785SLOPE 0.436(LAKE+1)-0.328 ROFF 1.011 Q5 = 4.62 DAREA0.795SLOPE 0.453(LAKE+1)-0.392 ROFF 0.78 Q10 = 7.98 DAREA0.799SLOPE 0.456(LAKE+1)-0.419 ROFF 0.671 Q50 = 19.9 DAREA0.803SLOPE 0.455(LAKE+1)-0.458 ROFF0.507 Q500 = 48.9 DAREA0.803SLOPE 0.449(LAKE+1)-0.488 ROFF0.376 Qn = discharge with return interval n in years (cfs) DAREA = drainage area (sq. miles) SLOPE = channel slope (feet / mile) LAKE = area covered by lakes (as % of drainage area, 0=1%) ROFF = generalized mean annual runoff (in) Note: analogous reports also available for estimating low-flow statistics

  14. Mean annual runoff

  15. Estimating flow duration curve in ungaged basins • Assuming there is a gaged basin nearby (similar climate, vegetation, rock type, etc): • Plot Q/Q2 vs % time exceeded for the gaged basin • Estimate Q2 for the ungaged stream assuming Q2 = bankfull Q • Estimate other % time exceeded for a given Q by multiplying the Q/Q2 value from the gaged curve by the Q2 value for the ungaged stream

  16. Example Q/Q2

More Related