Soils 456 Laboratory 7

 

Title : Furrow and Boarder irrigation Laboratory

Objective:To familiarize the students with furrow and boarder irrigation

Furrow Irrigation

Procedure: A furrow 1,000 ft long in soil having an infiltration rate of 1 inch per hr is irrigated for 5 hours with a stream of 45 gpm. This represent an area of 0.069 acres since the row spacing is 3 ft.

Advance and Recession Data

Advance Time After Start hrs. Advance( ft) Recession (ft)
0 0 -
.33 200 -
.7 400 -
1.4 600 -
2.3 800 -
4 1000 -
     
5 - 0
5.2 - 200
5.4 - 400
5.6 - 600
5.8 - 800

6

-

1000

 

1.a.Plot the advance and recession curves on the computer

b.Compute the time that surface water is in the furrow at each section

c. Compute the inches of water that enters the soil at each station.

2. Determine water distribution efficiency

3. Assuming that four inches of water had been depleted from the soil before irrigation, compute the application efficiency.

Boarder Irrigation

A flat border- strip 43.5 feet wide and 2000 ft long with a border across the lower end to prevent runoff is being irrigated with 2 cfs. Assuming that 3 inches of available water have been depleted before irrigation and that the soil has a constant intake rat of 0.5 inches per hours compute

1. The cfs flowing on the ground surface across the head end of each section

2. The cfs infiltrating into each 500 ft strip after the section is covered with water.

3. The cfs on the ground surface reaching the lower end of each sections. Show the formulas used and your computations and record appropriate data in the table below

Section distance from}
head of boarder ( ft)
Area per section
(acres)
Hours required
from start to reach
lower end of each section (hrs).
cfs flowing
across head end
of each section (cfs)
cfs infiltrating into each
500 ft strip after
section is covered with
water (cfs )
cfs reaching
lower end of each
section (cfs)
0-500 0.5 1      
500-1000 0.5 2.1      
1000-1500 0.5 3.3      
1500-2000 0.5 4.6      
           

4. If the turnout is shut as the stream reaches the 1500 ft station, how many inches of water will be applied to the entire border if the stream coasts to the low end after shut-off time.

5. Compute the water application efficiency.

6. For your information qt=ad

where
q=cfs
a=acre
d=inches
t= hours.

 

 

ANS