DRAINAGE OF WET LANDS OF SOUTHERN LOUISIANA. 57 



cast-iron centrifugal pumps, this type having proved to be very reliable. Con- 

 tinuous runs of 140 hours have been made without trouble. 



On most of the pumps the suction and discharge piping has been so arranged 

 that the friction losses are small, and the areas of intake and discharge open- 

 ings of the pipes have been enlarged to decrease velocity head losses. On some 

 plants this velocity head loss often amounts to 4 feet, and as a result the plant 

 does nearly twice the amount of work necessary. The piping of the centrifugal 

 pump on area No. 1 and on two pumps on area No. 11 is not enlarged or 

 tapered, and there are large losses due to this defect. All of the more modern 

 pumps have large intake and discharge openings, and the pipes often are 

 tapered the full length. When the suction ends of the intake pipes are cut 

 vertically whirlpools will develop over the pipes and air will be admitted, even 

 when the water is 2 feet deep over the pipes. If these pipes be cut horizontally 

 the water can be lowered to within an inch of the ends of the pipes before air 

 enters. 



On the smaller and older districts simple and reliable engines have been used, 

 but most of them have a very large steam consumption. Reliability and low 

 first cost have been sought, but, due to low-class labor, many of these plants 

 have had frequent breakdowns and large repair charges. A few of the large 

 districts are installing high-class machinery, and one, as shown in the sum- 

 mary, has installed cross-compound condensing engines and water-tube boilers. 

 Gasoline engines have been used on one small plant only, and although fairly 

 satisfactory no general use of them is expected. 



Owing to the mild nature of the climate very few of the plants have been in- 

 closed in permanent structures. Timber frame structures covered with heavy 

 corrugated galvanized iron are very common among the plants, and while these 

 are quite durable the danger from fire is very great. Two plants of this type 

 have recently burned. 



The cost of such plants as those described ranges from $4 to $7 per acre of 

 the district drained, according to the type and the capacity of the machinery. 



VEGETATION AND DEPTH OF DRAINAGE. 



As noted in the general description of this section, most of this land, whether 

 salt or fresh-water marsh, is covered with a heavy growth of grass (see PL 

 II, fig. 1). This seems to thrive even if the land is continuously submerged 

 with a small depth of water. However, when the land is drained sufficiently 

 to remove the water from the surface this grass grows much more luxuriantly, 

 and has been cut for hay two to four times in a single season. It appears to 

 grow better with deeper drainage. When cut for hay it makes excellent feed for 

 stock, and is much in favor with all the local planters who have given it a feed- 

 ing test. Deeper drainage is required for cane and corn, although fair crops 

 of corn have been grown with only about one foot of drainage. It would appear 

 that good crops can be grown if the water is held down to 2 feet below the sur- 

 face, but all planters are of the opinion that the deeper the drainage the better, 

 down to a depth of 3i feet. The truck crops all require complete and early 

 drainage, but not necessarily as deep as that required for cane and corn. As 

 droughts are of rare occurrence, not much trouble has been experienced in 

 getting the ground water too low in the soil. By proper management of the 

 pumping plant the stage of water in the canals and ditches can be so arranged 

 that the water will not be reduced too great a distance below the surface. This 

 artificial control of the water content of the soil is of decided advantage, and 

 it should make these lands as independent of natural conditions as are the 

 irrigated lands of the West. Crops on the muck lands seem to withstand 



