Use of Rational and Modified Rational Method for ... - CTR Library
Use of Rational and Modified Rational Method for ... - CTR Library
Use of Rational and Modified Rational Method for ... - CTR Library
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Technical Report Documentation Page<br />
1. Report No.:<br />
2. Government Accession No.: 3. Recipient’s Catalog No.:<br />
FHWA/TX–08/0–6070–1<br />
4. Title <strong>and</strong> Subtitle:<br />
<strong>Use</strong> <strong>of</strong> the <strong>Rational</strong> <strong>and</strong> <strong>Modified</strong> <strong>Rational</strong> <strong>Method</strong> <strong>for</strong> Hydraulic Design<br />
5. Report Date:<br />
February 28, 2011<br />
6. Per<strong>for</strong>ming Organization Code:<br />
7. Author(s):<br />
Theodore G. Clevel<strong>and</strong>, David B. Thompson, <strong>and</strong> Xing Fang<br />
9. Per<strong>for</strong>ming Organization Name <strong>and</strong> Address:<br />
Texas Tech University<br />
College <strong>of</strong> Engineering<br />
Box 41023<br />
Lubbock, Texas 79409-1023<br />
12. Sponsoring Agency Name <strong>and</strong> Address<br />
Texas Department <strong>of</strong> Transportation<br />
Research <strong>and</strong> Technology Implementation Office<br />
P. O. Box 5080<br />
Austin, TX 78763-5080<br />
8. Per<strong>for</strong>ming Organization<br />
Report No. 0–6070–1<br />
10. Work Unit No. (TRAIS):<br />
11. Contract or Grant No. :<br />
Project 0–6070<br />
13. Type <strong>of</strong> Report <strong>and</strong> Period<br />
Cover:<br />
Technical Report: September 2007–<br />
August 2010<br />
14. Sponsoring Agency Code:<br />
15. Supplementary Notes:<br />
This study was conducted in cooperation with the Texas Department <strong>of</strong> Transportation <strong>and</strong> the Federal Highway<br />
Administration.<br />
16. Abstract:<br />
This report examines the rational <strong>and</strong> modified rational methods using rainfall-run<strong>of</strong>f datasets developed from<br />
Texas watersheds <strong>for</strong> application to Texas Department <strong>of</strong> Transportation hydraulic design problems.<br />
A unified rational method <strong>for</strong> Texas (URAT) is proposed as an alternative to the conventional method in current<br />
use. URAT substitutes l<strong>and</strong>-use specification, slope influence, <strong>and</strong> probability adjustments to run<strong>of</strong>f coefficients by<br />
a simple area-weighted coefficient based on functional impervious cover. URAT incorporates the effect <strong>of</strong> slope<br />
<strong>and</strong> probability adjustments in the specification <strong>of</strong> the watershed time <strong>of</strong> equivalence, a characteristic time that<br />
makes rational peak discharges <strong>and</strong> regression equation peak discharges equal at some specified recurrence interval.<br />
An extended application (example) is presented to illustrate how to use the URAT method <strong>for</strong> both peak discharge<br />
<strong>and</strong> hydrograph estimation. Several appendices document various approaches examined, <strong>and</strong> provide an extensive<br />
examination into the run<strong>of</strong>f coefficient.<br />
17. Key Words<br />
Hydrology, hydraulics, rational method, modified<br />
rational method<br />
19. Security Classif. (<strong>of</strong> this report)<br />
Unclassified<br />
Form DOT F 1700.7 (8-72)<br />
20. Security Classif. (<strong>of</strong> this page)<br />
Unclassified<br />
18. Distribution Statement<br />
No restrictions. Document available to public<br />
through National Technical In<strong>for</strong>mation Service,<br />
Springfield, VA 22161, www.ntis.gov<br />
21. No. Pages<br />
157<br />
22. Price
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