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:
  Design Methods Drainage Structures Floods Rational Formula (Hydraulics) Regression Analysis Runoff Watersheds
• 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.
  
  
• Format:
  PDF
• Funding:
  C1912
• Collection(s):
  University Transportation Centers US Transportation Collection
• Main Document Checksum:
  urn:sha256:8fab10c4104d292f83fa183def3571b276acdd9bb3ceb917a986499ce3a62883
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/26040/dot_26040_DS1.pdf
• File Type:
  [PDF - 2.41 MB ]