DRAINAGE OF WET LANDS OF SOUTHERN LOUISIANA. 19 



excellent illustration of an area that eventually will need better outlet facili- 

 ties, parts of this area discharging drainage water through 80 miles of natural 

 drainage channel to reach the Gulf. As shown by the gauge at Lockport, the 

 natural water surface in the swamps already has a large fluctuation, and any 

 further extensive reclamation of land without improvement of the main 

 drainage channels will doubtless considerably increase this fluctuation. A 

 survey of this area would be needed to determine whether or not the present 

 channel should be improved or whether any channels should be cut through the 

 central portion of the district. Local landholders have suggested the possi- 

 bility of combining such a main drainage outlet with a commercial canal to the 

 Gulf, thus affording the district better transportation facilities. A thorough 

 survey of the district would determine the feasibility of such a combination of 

 interests. 



River Overflow. 



Like all delta regions this one was originally subject to periodic overflow. 

 The smaller floods of the Mississippi River were confined within the natural 

 levees that the stream itself has built up, but at irregular intervals of some 

 years great floods would for months cover practically all of the delta. As soon 

 as any serious attempt was made to bring this land under cultivation, levees 

 were built along the Mississippi River banks to protect the lands from overflow. 

 Districts were finally organized which included long stretches of river, and in 

 all millions of dollars have been spent in levee improvements. This expendi- 

 ture, with such Federal aid as has been available, has built a continuous levee 

 system on both banks of the river throughout its length in the district under 

 consideration. The levees have been increased in size as fast as the protected 

 land could supply the money. In the earlier years, owing to insufficient cross 

 section of levees and low grade line, crevasses were of frequent occurrence in 

 times of high water. As more and more work was done on the levees a greater 

 degree of protection was secured, until now crevasses and consequent overflow are 

 very rare and occur only at times of record-breaking floods. The levee system is 

 still far from complete. As illustrative of the flooding possibilities due to crevasses 

 in the present system of levees, figure 3, published by courtesy of the Mississippi 

 River Commission, shows the area overflowed during the record-breaking flood 

 of 1912. It is evident that not only the reclamation of the swamp land but 

 the successful cultivation of practically all of the higher land east of the Atcha- 

 falaya River is dependent upon the prevention of overflow of the Mississippi 

 River. The interests involved in such overflow and the damage resulting are 

 of such ever-increasing magnitude that there is every reason to believe that the 

 work of completing these levees will be done in the immediate future. Promi- 

 nent levee engineers who are acquainted with the problem believe that with 

 the completion of the levee system this whole area will be protected from over- 

 flow of the Mississippi River. The above remarks apply to the alluvial section 

 of the country, as very little land west of the Atchafalaya River is affected by 

 Mississippi overflow. Some of the larger streams, such as the Calcasieu and the 

 Sabine, flood the alluvial flats of land immediately along their banks to a depth 

 of perhaps 4 feet, but as a whole the wet prairie lands of this western portion 

 of the coast are free from river overflow. 



Tidal Overflow. 



The daily range of tide along this portion of the Gulf coast is quite small, the 

 average being from 0.5 to 1.5 foot. However, as is true of all low, flat coasts 

 bordering on wide areas of comparatively shallow water, heavy winds which 



