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Drainage Design Manual, Hydrology - Flood Control District of ...

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<strong>Drainage</strong> <strong>Design</strong> <strong>Manual</strong> for Maricopa County<br />

<strong>Hydrology</strong>: Acknowledgements, Comments & Revisions<br />

mining the design rainfall criteria were expanded. NOAA Atlas 2 was dropped and NOAA Atlas<br />

14 was <strong>of</strong>ficially adopted. The isopluvial figures were moved to Appendix A.<br />

Chapter 3 Rational Method – The I-D-F graph was replaced with a new IDF based on NOAA<br />

Atlas 14 and then moved to Appendix B. A discussion <strong>of</strong> the computation <strong>of</strong> site specific intensities<br />

was added and is intended to replace the I-D-F graph. Procedures for determination <strong>of</strong> peak<br />

discharge at multiple points in a drainage network was added. A triangular hydrograph approach<br />

was added for combining and translating Rational Method peak discharges.<br />

Chapter 4 Rainfall Losses – Procedures for the determination <strong>of</strong> the rainfall loss variables <strong>of</strong><br />

the Green and Ampt equation were expanded.<br />

Chapter 5 Unit Hydrograph – Procedures for the determination <strong>of</strong> the Clark unit hydrograph<br />

parameters and the S-Graph ordinates were expanded. The Clark unit hydrograph time <strong>of</strong> concentration<br />

procedure for estimating average rainfall excess intensity was revised.<br />

Chapter 6 Multiple Frequency Modeling – This is an entirely new chapter.<br />

Chapter 7 Channel Routing – The Channel Routing chapter was changed to Chapter 7. The<br />

contents <strong>of</strong> this chapter were reorganized.<br />

Chapter 8 Indirect Methods – This is an entirely new chapter.<br />

Chapter 9 Application – The Application chapter was changed to Chapter 9. The procedures<br />

presented in Chapters 2 through 8 were added. User notes regarding the procedures and application<br />

<strong>of</strong> the methodologies presented in this manual were added along with detailed examples<br />

specific to each chapter.<br />

Fourth Edition Dates <strong>of</strong> Revisions<br />

The following indicates the dates in which the fourth edition has been updated and summarizes<br />

revisions made after the release <strong>of</strong> this fourth edition.<br />

01/07/2010 Corrected typographical error on page 9-22.<br />

04/24/2013 Corrected typographical errors on Page 9-6.<br />

05/09/2013 Corrected a typographical error on page B-2<br />

08/15/2013 Finalized fourth edition.<br />

August 15, 2013<br />

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