LAND DRAINAGE BY MEANS OF PUMPS. 



49 



AMOUNT AND COST OF PUMPING. 



Table 12 shows the yearly rainfall and amounts pumped for the 

 four districts already mentioned under " Necessary capacity of pump- 

 ing machinery." It will be noted that there is considerable varia- 

 tion in the relation between rainfall and amount pumped for different 

 years on the same district, and for the different districts during the 

 same year. The average percentage of the rainfall pumped was 40.6 

 per cent if based upon the total yearly rainfall, or 46.7 per cent con- 

 sidering only the rainfall during the months when pumping was going 

 on. The average annual rainfall for the above four stations for all 

 the years available was only 26.21 inches, while the average annual 

 rainfall for the Weather Bureau stations at Muscatine, Peoria, and 

 St. Louis is 37.39 inches. Assuming that the ratio would be the same, 

 40.6 per cent, if the rainfall were normal, we might expect the amount 

 to be pumped as a depth of 15.18 inches. Moreover, as the percent- 

 age of the rainfall appearing as run-off is usually greater during wet 

 years than in dry ones, the above figure would more likely be less 

 than the average run-off rather than greater. Those districts which 

 do not have gravity sluices may well expect to do more pumping 

 than those which have, although most of the rainfall and pumping 

 occur at the time of the year when the rivers are high. 







Table 12 



. — Annual 



rainj 



all and amounts 



pumped. 









District. 



1912 



1913 



1914 



Total. 



Per cent of 



rainfall in 



run-off. 





Rain- 

 falU 



Rain- 

 fall^ 



Run- 

 off. 



Rain- 

 fall, i 



Rain- 

 fall.2 



Run- 

 off. 



Rain- 

 fall.i 



Rain- 

 falls 



Run- 

 off. 



Rain- 

 fall.! 



Rain- 

 fall.2 



Run- 

 off. 



Rain- 

 fall. i 



Raln- 

 fall.2 



Louisa - D e s 

 Moines 



In. 

 25.67 



34.49 



In. 

 15.07 



34.49 



In. 

 15. 15 



13.41 



In. 

 28.16 



26.05 



In. 



14.84 



26.05 



In. 

 11.32 



11.80 



In. 



In. 



In. 



In. 

 53.83 



81.39 

 22. 75 

 25. 50 



In. 

 29.91 



81.39 

 22.75 

 25.50 



In. 



26.47 



30.08 

 6.98 

 10.98 



49.1 



37.0 

 30.8 

 43.6 



88.5 



Pek in-La 

 Marsh 



20.85 

 22.75 

 25. 50 



20. 85 

 22.75 

 25.50 



4.87 

 6.98 

 10.98 



37.0 

 30 8 



Coal Creek 















43.6 



















Average. 



Per rent of 

 rainfall in 

 run-off 



30. 08 

 47.5 



24. 78 

 57.6 



14.28 



27.11 

 42.6 



20.44 

 56.6 



11.56 



23.03 

 33.0 



23.03 

 33.0 



7.61 



26.21 

 40.6 



22. 79 

 46.7 



10.64 



40.6 



46.7 













Total rainfall for year. 2 Rainfall for months during which drainage was secured by means of pumps. 



The cost of operation of pumping plants for drainage pumping will 

 vary largely according to type of machinery and the method of opera- 

 lioii. While the cost of operation of various types of machinery is 

 well understood, the conditions obtaining on the average drainage 

 districl are likely to affect seriously the accepted cost figures. In 

 view of this fact cost data were obtained from a number of drainage 

 pumping plants now in operation. The operating expenses were 

 c! rifled under "Labor," "Fuel," "Repairs," "Supplies," and 

 "Superintendence." Tables 13 and 14 give the cost of such items, 

 per acre per year, for a number of districts. As some districts have 



