44 



BULLETIN 1017, U. S. DEPARTMENT OE AGRICULTURE. 



of annual run-off to annual precipitation was computed. The data 

 for the area above Grand Forks are shown in figure 16. On that 

 watershed the run-off in 1897 was maximum both in depth (3.2 

 inches) and in percentage of annual precipitation (14.3 per cent). 

 In 1916, when maximum recorded annual precipitation occurred, 

 the run-off (3.1 inches) was nearly maximum, but the percentage 

 of precipitation (11.2 per cent) that appeared as run-off was less 



1882 



1883 



1884 



1885 



1886 



1887 



1888 



1889 



1890 



1891 



1892 



1893 



1894 



1895 



1896 



1897 



1898 



1899 



1900 



1901 



1902 



1903 



1904 



1905 



1906 



1907 



1908 



1909 



1910 



!9I 



1912 



1913 



1914 



1915 



1916 



1917 



191 



1919 



Depth in Inches 



5 10 15 20 25 



ISE — ' ' ' 



' — 









1 











H 









, 











H 



i 



1 1 

















m 

















I 













I , 





i 













m 



• 







*" 1 1 ' 









i 





i 





























I 



■ 



i 





1 











m 







I 





i 





1 









i 











I 





























i 



m 



i 













i 



* 





i 



i 











i 



i 













1 









i 































i 1 » 



1916 

 1882 

 1896 

 1905 

 1901 

 1891 

 1884 

 1906 

 1914 

 1900 

 1915 

 1919 

 1912 

 1902 

 1909 

 1897 

 1911 

 1904 

 1908 

 1903 

 1887 

 1892 

 1899 

 1893 

 1890 

 1898 

 1918 

 1913 

 1895 

 1894 

 1886 

 1883 

 1885 

 1807 

 1888 

 1889 

 1917 

 1910 



11.2 

 11.7 



7.7 

 7.1 

 6.5 

 3.1 

 6.7 

 9!6 

 3.7 

 4.6 

 6.5 

 5.7 

 2.2 

 7.6 

 6.3 



0) 



0; 



Depth in Inches 



5 10 15 20 25 





30 



3.1 

 3.2 

 2.1 

 1.9 

 1.7 

 0.8 

 1.7 

 2.4 

 09 

 I.I 

 1.5 

 1.3 

 0.5 

 1.7 

 1.4 



^E 



14.3 (Max.) 3.2 

 .8(Min}0.4 



10.1 



73 



7.3 



3.7 



10.5 



6.8 



10.3 



3.0 



5.1 



Z6 



3.6 



3.1 



6.7 



6.4 



11.7 



9.6 



10.3 



10.5 



3.3 



9.0 



9.9 



2A 

 1.6 

 1.6 

 0.S 

 2.2 

 1.4 

 2.1 

 0.6 

 1.0 

 0.5 

 0.7 

 0.6 

 1.3 

 1.2 

 21 



05 F 



1.2 

 1.2 



rs: 



K 



MEAN 7.0 



.5Nc 



27.8 



27.4 



27.2 



26.9 



26.0 



25.6 



25.3 



25.0 



24.2 



23.8 



23.1 



23.0 



22.6 



22.5 



22.3 



22.3 



22.2 



22.1 



21.8 



21.8 



21.8 



21.0 



20.6 



20.4 



20.3 



19.8 



19.6 



19.5 



19.5 



19.3 



18.8 



18.7 



18.7 



18.5 



17.1 



153 



13.4 



12.0 



21.5 



Fig. 16. — Annual precipitation and run-off on Red River of the North watershed above 



Grand Forks, N. Dak. 



than for 1897. The run-off during 1897 was increased by the heavy 

 precipitation of 1896, by maximum depth of snow on the ground 

 in March, 1897, and by extremely heavy monthly and storm pre- 

 cipitation during July, 1897. 



Probable future maximum run-off as estimated from a study of all 

 available data for the four watersheds mentioned above is indi- 

 cated in Table 11. It is improbable, however, that run-off equiva- 



