24 



BULLETIN 1017, U. S. DEPARTMENT OF AGRICULTURE. 



until in 1921 about 50 were maintained within the Red River water- 

 shed (see fig. 1). Daily precipitation records are available for 

 twenty or more stations for the period 1892 to 1919. 



DISTRIBUTION OF PRECIPITATION. 



In making the study of precipitation data the contributing area 

 south of the international boundary was divided into seven areas as 

 indicated in figure 5. This facilitated the determination of the pre- 

 cipitation on watersheds of various tributary streams and on areas 

 above certain stream-gaging stations; it also made evident the rela- 

 tions between size of watershed and intensity of precipitation. 



CANADA 



SOUTH DAKOTA 



Fig. o. — Outline watershed map of Red River of the North, showing subdivisions for 



precipitation studies. 



The precipitation records were considered in four classes — annual, 

 monthly, and storm periods, and the period during which snow is 

 stored. The annual, monthly, and storm precipitations were com- 

 puted from the records for each area and weighted averages were 

 computed for certain larger areas whiclrcomprise two or more of the 

 subareas. The records prior to 1892 are too meager to afford satis- 

 factory basis for estimating the distribution of precipitation over 

 these areas. 



