Soils 456 Notes Chapter 5
Triangular and Square
S= spacing between sprinklers
L= spacing between rows of sprinklers mounted on the lateral lines
For triangular spacing sprinklers are spaced equal distances from each other and L= S* 0.866
Values of Ks for different spacing.
s< ks* Dt where Dt is diameter of through
The boundary of a lawn is 110 ft. Maximum spacing is 30 ft. based on wind speed and Dt.
Spacing 110/ 4=27.5 ft.
2. Precipitation rate
P=q/Ar P= 96.3 q/A
Where P= in/hr
Example 5.2 in book.
3. Application Uniformity
Christiansen's Coefficient of Uniformity
CU = 100 (1-D/M)
D = (1/n) å ½Xi-M ½
M = (1/n) å Xi
Where: CU = Christiansen's Coefficient of Uniformity (%)
D = Average Absolute Deviation From the Mean
M = Mean Application
Xi = Individual Application Amounts
n = Number of Individual Application Amounts
Statistical Uniformity= Standard deviation/ mean *100
Value should be higher than 80% and 90% is better.
4. The total water applied to the field must satisfy the water needs of the crop in all or part of the field and must satisfy the leaching requirement. The definition of irrigation application efficiency is the Et / Water Applied and can be calculated for one irrigation or the season. See Dr. Lamm paper for a complete discussion