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 
rainjall and amounts pumped. 
District. 
1912 
1913 
1914 
Total. 
Per cent of 
rainfall in 
run-off. 
Rain- 
Mi. i 
Rain- 
fall.2 
Run- 
off. 
Rain- 
fall.! 
Rain- 
fall. 2 
Run- 
off. 
Rain- 
fall.* 
Rain- 
fall.2 
Run- 
off. 
Rain- 
faU.i 
Rain- 
foil. 2 
Run- 
off. 
Rain- 
fall.* 
Rain- 
foll.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 
Pekin-La 
Marsh 
East Peoria. .. 
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 cent 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 
1 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- 
tion. While the cost of operation of various types of machinery is 
well understood, the conditions obtaining on the average drainage 
district 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 
classified 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 
