94 



4. A flowchart showing program logic for computation of days 

 saturated is provided in Figure C-l. 



Computation of Frequency of Inundation 



General . Frequency of inundation was not used in defining hydro - 

 logic zone boundaries. However, it was used for discussion purposes. 



Frequency of inundation for a given flow rate was determined by: 



1. Counting the number of growing seasons in the historic record 

 during which the flow rate for a particular hydrologic zone 

 was exceeded at least once for a minimum of 7 days. 



2. Dividing the total number of years in the record into "a," and 

 multiplying by 100. 



For example: A flow rate of 20,000 cubic feet per second is exceeded in 

 only two growing seasons of a 20-year record. This flow rate has a fre- 

 quency of inundation of 2/20 x 100 = 10 percent. 



Computation of Parameters in Tabular Output 



Tabular output appeared as follows : 



(1) 



(2) 



(3) 



(4) 



(5) 



(6) 

 DAYS 



(7) 

 DURATION 





DAYS 





FREQ 





SATURATED 



SATURATED 



BOUNDARY 



INUN- 



DURATION 



INUN- 



DAYS 



PLUS DAYS 



AND 



FLOWRATE 



DATED 



INUNDATED 



DATED 



SATURATED 



INUNDATED 



INUNDATED 



38852. 



33. 



4.3 



100.0 



38 



5.0 



All of the above have already been explained except columns (3) , (6) and 

 (7). 



Column 3 - 



Duration inundated 



days inundated 



x 100. 



total growing season 



2. Column 6 - Days saturated plus days inundated = Columns 2+5. 



3 . Column 7 - 



Duration saturated 

 and inundated 



days inundated + 



days saturated 



total growing season days 



x 100. 



