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UNITED STATES DEPARTMENT OF AGRICULTURE 

 BULLETIN No. 854 



Contribution from the Bureau of Public Roads 

 THOS. H. MACDONALD, Chief 



Washington, D. C. 



PROFESSIONAL PAPER 



August 26, 1920 



THE FLOW OF WATER IN DRAIN TILE 



By 



D. L. YARNELL, Senior Drainage Engineer, and SHERMAN M. 



WOODWARD, Professor of Mechanics and Hydraulics 



State University of Iowa 



CONTENTS 



Page 



Introduction 1 



Scope of the Investigation 2 



Conclusions 4 



Description of Experimental Plant . . . 5 



Pumping Plant S 



Supply Tanks 5 



Weirs 6 



Hook Gages 6 



Flume 6 



Method of Changing Grade .... 6 



Laying the Tile ........ 7 



Covering the Tile 7 



Piezometers and Piezometer Tubes . 8 



Nomenclature 9 



Formula; for Flow of Water in Drain Tile 9 



Page 

 Necessary Data for Comparing Velocity 



Formula; 12 



Mean Velocity 12 



Hydraulic Grade or Slope .... 12 



Internal Size of Drain Tile .... 13 



Actual Depth of Flow 14 



Methods of Conducting Tests .... 15 



Measurement of Mean Velocity ... 17 



Results of Observations IS 



Discussion of Computations 34 



Formula; for Tile Flowing Full . . . 35 



Formula; for Tile Flowing Partly Full 40 



Comparison of Various Formula; ... 47 



Loss of Head in Catch-Basins .... 49 



WASHINGTON 



GOVERNMENT PRINTING OFFICE 



1920 



