Evaluation of Design Flood Frequency Methods for Iowa Streams, TR-533, 2009

(2009) Evaluation of Design Flood Frequency Methods for Iowa Streams, TR-533, 2009. Transportation, Department of

Preview	PDF IADOT_tr_533_Eval_Design_Flood_Freq_Methods_Iowa_Streams_2009.pdf File Size:1MB
Preview	PDF TR-533 Tech Brief.pdf File Size:265kB

Abstract

The objective of this project was to assess the predictive accuracy of flood frequency estimation for small Iowa streams based on the Rational Method, the NRCS curve number approach, and the Iowa Runoff Chart. The evaluation was based on comparisons of flood frequency estimates at sites with sufficiently long streamgage records in the Midwest, and selected urban sites throughout the United States. The predictive accuracy and systematic biases (under- or over-estimation) of the approaches was evaluated based on forty-six Midwest sites and twenty-one urban sites. The sensitivity of several watershed characteristics such as soil properties, slope, and land use classification was also explored. Recommendations on needed changes or refinements for applications to Iowa streams are made.