Soils 456 Irrigation and Drainage Answers to chapter 5 questions

5.1

Model 570 sprinkler 15 ft series operated at 30 lb/in.^2. Wind 5
mph

Radius of throw 15 ft

s<ksDt

ks= .5 for square spacing and .55 for triangular spacing

square spacing= .5*30= 15 ft

triangular spacing .55*30= 16.5 ft

5.2

sprinkler radius of throw 22.ft

ks= 0.45

s= .45*44= 19.8

5.3

Boundry of 300 ft , wind 3mph , sprinkler radius of throw 35

square spacing k= 0.55

s= 0.55*70=38.5 ft

spacing = 300ft/6=33ft

5.4

area 66ft* 83 ft, sprinkler model 300 Toro head , wind 7 mph

ks= 0.55 triangular spacing and 0.5 square spacing

66ft/4=16.5 ft

83ft/5= 16.6 ft

spacing =ksD= 0.5*16.6*2= 16.6ft

select 300 nozzle 01 psi 35= 16 ft of throw

select 300 nozzle 01 50 psi= 18 ft of throw

operate 300 nozzle 01 at 39 psi to throw 16.6ft. square spacing

5.5

Triangular spacing l=0.866s k=0.55

five sprinklers spaced 16.6ft

check 16.5= 0.55*D D=30 ft radius=15ft but lowest pressure 35psi
at D= 16ft

Set 5 sprinklers at 16.5ft

l=0.866s= 0.866*16.5=14.6ft

length 66ft/5=13.2ft for lateral spacing which is less than 14.6 ft

5.6

Christansen's unifromity for:

1,0.9,0.7,1.2 inches

5.7

Using a Toro model 700 sprinkler head . The ks value is 0.5

Use a nozzle size of 1.0 at a pressure of 25 psi which has a radius of throw of 34 ft. Spacing is 21.7 feet so some water will throw into sidewalk. Design in book is the best.

5.8

Area 40 ft by 50 ft has full cicrle 4 gal/min sprinklers located
at each corned

Pricipitation = 96.3 * 4/ 40*50=0 .192 in/hr.

5.9

A 12 m x 15 m area has quater-circle 0.25 l/s sprinkler at each corner.

15m= 49.2 ft, 12 m= 39.3 ft, .25 l/s= 4.03 gmp

p= 96.3 *4.04/49.2*39.3= 0.2 in/hr-0.51 cm/hr

5.10

SC= 95/.7-1.35

BC= 0.95/1.2=0.79