Estimating design discharges for drainage structures in western Kansas.

Details

• Creators:
  McEnroe, Bruce M. ; Young, C. Bryan ; Williams, Aaron R. ; Hinshaw, Matt
• Corporate Creators:
  University of Kansas. Dept. of Civil, Environmental and Architectural Engineering
• Corporate Contributors:
  Kansas State University. Transportation Center ; United States. Dept. of Transportation. Research and Innovative Technology Administration
• Subject/TRT Terms:
  • Drainage structures
  • Design methods
  • Runoff
  • Floods
  • Watersheds
  • Rational formula (Hydraulics)
  • Regression analysis
• Publication/ Report Number:
  K-TRAN: KU-12-4
• Resource Type:
  Tech Report
• Geographical Coverage:
  Kansas
• Corporate Publisher:
  Kansas. Dept. of Transportation. Bureau of Materials & Research
• NTL Classification:
  NTL-HIGHWAY/ROAD TRANSPORTATION-Bridges and Structures ; NTL-HIGHWAY/ROAD TRANSPORTATION-Design
• Abstract:
  KDOT engineers have expressed concern that the hydrologic methods in the current KDOT Design Manual (Volume I, ; Part C, 2011) may lead to over-sizing of drainage structures in Western Kansas. Some new structures designed by the current ; methods are much larger than the previous structures at these locations or existing structures directly upstream or downstream, ; where the older structures had no known history of overtopping. There are reasons to suspect that current methods may not be well ; suited to small watersheds in Western Kansas, particularly for areas with high soil permeability. ; This report examines the applicability of KDOT’s current hydrologic methods to Western Kansas and develops new ; Rational C values and flood-frequency regression equations for this region. In addition, KDOT’s current hydrologic methods are ; compared with those of nearby state DOTs. ; In order to develop new flood-frequency regression equations and recommendations for Rational C values for Western ; Kansas, we assembled a data set of all USGS gaging stations that met the following criteria: (1) at least 10 years of peak flow ; records, (2) watershed area less than 100 mi2, (3) unregulated watersheds (no major lakes or reservoirs), and (4) watersheds within ; 100 miles of the Kansas border and west of 97.5° longitude. The resulting data set contains 156 stations, 62 of which are in ; Kansas. ; Regional flood frequency analyses were performed on this data set using Generalize Least Squares regression in WREG ; 1.0. Soil permeability was found not to be a significant predictor variable. Regression equations were developed for Western ; Kansas, but our comparisons show that these equations are not a substantial improvement over existing regression equations. ; Based on an evaluation of available methods, we recommend the Extended Rational method for watershed areas > 640 ac and < 30 ; mi2 and the USGS four-parameter regression equation for watersheds ≥ 30 mi2 in both Western and Eastern Kansas. ; An analysis of Rational C values indicates that C values currently used for design in Western Kansas are too high for ; recurrence intervals below 100 years. New Rational C values for Western Kansas were developed and checked against regression ; methods for consistency. Our proposed C values for Western Kansas are lower than the current values for all recurrence intervals ; below 100 years. We also propose certain adjustments to the Rational C values for Eastern Kansas. We recommend that urban open ; spaces and pervious surfaces within the right-of-way be considered equivalent to pasture/range rather than cropland in both ; Western and Eastern Kansas.
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• Format:
  PDF
• Funding:
  C1912
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/26040/dot_26040_DS1.pdf
• File Type:
  [PDF - 2.41 MB]
• Collection(s):
  University Transportation Centers ; US Transportation Collection
• Main Document Checksum:
  urn:sha-512:943ddfda2d01b4791e3c4b6e53bb1e753f85b68854161a0853f5642f686dddd95fde33df81a6ae5db78996c8ed1d91dc6e98dc48b1eb9bb20e2133bb269a8500