CYPEESS CEEEK DEAIXAGE DISTEICT, ARKANSAS. 7 



whose backwater enters the district through the gap in the levees 

 at the mouth of Cypress Creek, damaging not only the district itself 

 but a large area in Chicot County, Arkansas, and northern Louisiana^, 

 since such water, once behind the Mississippi River levee, must flow 

 south to the Red River. The drainage problem, then, is not only 

 to provide the necessary outlets and laterals to care for the run-off 

 from the 658 square miles tributary to the district, but to so design 

 and locate these outlets that the drainage water now entering the 

 Mississippi River through the levee gap will be diverted, thus making 

 it possible to close this gap. With the construction of these outlets 

 and the closing of the levee gap the reclamation of the district will 

 be assm*ed. 



RUN-OFF. 



No phase of the preliminary study of a drainage project has a more 

 vital bearing upon the success of the undertaking than the determi- 

 nation of the rate of run-off for which provision must be made. Obvi- 

 ously, precipitation is the most important element to be considered 

 in the study of run-off, although certain other factors have more or 

 less effect upon the rate of run-off. These are the size, shape, and 

 topography of the watershed; the character of soil and vegetation; 

 the rate of evaporation; the climate and seasons; and the water stor- 

 age capacity of the soil, stream channels, and other natural reservoirs. 



EUN-OFF INVESTIGATIONS MADE. 



RAINFALL. 



Southeast Arkansas is characterized by high humidity and heavy 

 rainfall. The rainfall records of the United States Weather Bureau 

 for Arkansas City and Pine Bluff have been carefully examined, the 

 former station being the only one in the Cypress Creek drainage dis- 

 trict. The records for Pine Bluff, however, may be taken as indi- 

 cating rainfall conditions on the upper portion of the Cypress Creek 

 watershed. 



The average annual rainfall for Arkansas City, including the year 

 1912^ is 45.23 inches, and for Pine Bluff, 49.63 inches. The records 

 for Arkansas City for the years 1897 to 1911, inclusive (not including 

 the years 1907 and 1908, for wbicli records are incomplete), show the 

 greatest annual rainfall to liave been 70 inches, in 1911, and the mini- 

 mum to have been 26.83 inches, in 1901. At Pine Bluff the maxi- 

 innrn annual rainfall for the same period was 82.89 inclies, in 1905, 

 and the minimum 37.21 inches, in 1901. The greatest monthly rain- 

 fall recorded at Arkansas City was 15.42 inclies in December, 1911, 

 and at Pine, i51uff, 15.71 inclies in May, 1905. 



Some of the heaviest storm periods at Arkansas City during the 16 

 years preceding 1913 were as follows : De(;ember 7-16, 191 1,9.7 inches; 



