Brae exam 1 questions with 100%
complete solutions already passed
Statements (1) and (2) refer to water requirements. Are these Net of Gross requirements?
(1) Each furrow requires 12 gallons per minute from the supply ditch.
(2) The peak use for cotton in this area is 0.3 inches per day. - correct answer ✔✔(1) is Gross; (2)
is Net
Statements (1) and (2) refer to water volumes. Are these Net or Gross volumes?
(1) Crop water use (cu-ft) = Seasonal ET (ft) x Crop area (acres) x 43,560 sq-ft/acre
(2) Plant water use (gal) = Plant area (sq-ft) x Plant water use (in) divided by 12 in/ft x 7.48
gal/cu-ft - correct answer ✔✔(1) is Net; (2) is Net
An irrigation system applies a gross amount of 48 inches of water during the growing season. An
evaluation determines that: 29 inches goes to satisfy crop ET; 8 inches runs off and is not
collected for reuse; 5 inches passes through the root zone as deep percolation (total), of which
2 inches are beneficial leaching for salt removal; and 1 inch is ET from weeds. What is the
irrigation efficiency (%)? - correct answer ✔✔64.6%
Benefical Uses (inches) = Crop ET + Crop Cooling + Leaching
IE (%) = Benficial IW (in) ÷ Total Applied (in) * 100
Usually, the most significant beneficial use of water is which of the following? - correct answer
✔✔Crop evapotranspiration (ETc)
Which of the following irrigation methods provides an excellent opportunity for leaching? -
correct answer ✔✔Basin
, A city of 892,013 people use 274 gallons of water per person per day. What is the city's water
use in acre-feet per year? - correct answer ✔✔273,794.8 ac-ft/yr
people x gal/person/day = gal/day
gal/day x 1 cu-ft/7.48 gal = cu-ft/day
cu-ft/day x 1 acre/43560 sq-ft = ac-ft/day
ac-ft/day x 365 days/year = ac-ft/yr
A farmer grows 89 acres of a crop that requires 33 inches (net) of irrigation per year. Water
costs $90 per ac-ft in this area. What would the annual water cost be if the irrigation efficiency
is 70%? - correct answer ✔✔$31,468/yr
Gross = Net (in) ÷ (IE/100) x 1 ft/12 in = ft/yr
Volume = Depth x Area
Volume = ft/yr x acres = ac-ft/yr
Cost = ac-ft/yr x $/ac-ft = $/yr
329,300 gallons of water are added to a reservoir (with straight sides) covering 4.3 acres. How
many inches does the water level rise after the water is added? - correct answer ✔✔2.8 inches
gallons ÷ 7.48 gal/cu-ft = cu-ft
cu-ft ÷ acres ÷ 43560 sq-ft/acre = ft
ft x 12 in/ft = inches
A metric sprinkler catalog shows a sprinkler that delivers 0.50 liters/sec (Lps) at an operating
pressure of 98 feet of head. What is the sprinkler flow rate in gallons per minute (gpm)? -
correct answer ✔✔7.9 gpm
complete solutions already passed
Statements (1) and (2) refer to water requirements. Are these Net of Gross requirements?
(1) Each furrow requires 12 gallons per minute from the supply ditch.
(2) The peak use for cotton in this area is 0.3 inches per day. - correct answer ✔✔(1) is Gross; (2)
is Net
Statements (1) and (2) refer to water volumes. Are these Net or Gross volumes?
(1) Crop water use (cu-ft) = Seasonal ET (ft) x Crop area (acres) x 43,560 sq-ft/acre
(2) Plant water use (gal) = Plant area (sq-ft) x Plant water use (in) divided by 12 in/ft x 7.48
gal/cu-ft - correct answer ✔✔(1) is Net; (2) is Net
An irrigation system applies a gross amount of 48 inches of water during the growing season. An
evaluation determines that: 29 inches goes to satisfy crop ET; 8 inches runs off and is not
collected for reuse; 5 inches passes through the root zone as deep percolation (total), of which
2 inches are beneficial leaching for salt removal; and 1 inch is ET from weeds. What is the
irrigation efficiency (%)? - correct answer ✔✔64.6%
Benefical Uses (inches) = Crop ET + Crop Cooling + Leaching
IE (%) = Benficial IW (in) ÷ Total Applied (in) * 100
Usually, the most significant beneficial use of water is which of the following? - correct answer
✔✔Crop evapotranspiration (ETc)
Which of the following irrigation methods provides an excellent opportunity for leaching? -
correct answer ✔✔Basin
, A city of 892,013 people use 274 gallons of water per person per day. What is the city's water
use in acre-feet per year? - correct answer ✔✔273,794.8 ac-ft/yr
people x gal/person/day = gal/day
gal/day x 1 cu-ft/7.48 gal = cu-ft/day
cu-ft/day x 1 acre/43560 sq-ft = ac-ft/day
ac-ft/day x 365 days/year = ac-ft/yr
A farmer grows 89 acres of a crop that requires 33 inches (net) of irrigation per year. Water
costs $90 per ac-ft in this area. What would the annual water cost be if the irrigation efficiency
is 70%? - correct answer ✔✔$31,468/yr
Gross = Net (in) ÷ (IE/100) x 1 ft/12 in = ft/yr
Volume = Depth x Area
Volume = ft/yr x acres = ac-ft/yr
Cost = ac-ft/yr x $/ac-ft = $/yr
329,300 gallons of water are added to a reservoir (with straight sides) covering 4.3 acres. How
many inches does the water level rise after the water is added? - correct answer ✔✔2.8 inches
gallons ÷ 7.48 gal/cu-ft = cu-ft
cu-ft ÷ acres ÷ 43560 sq-ft/acre = ft
ft x 12 in/ft = inches
A metric sprinkler catalog shows a sprinkler that delivers 0.50 liters/sec (Lps) at an operating
pressure of 98 feet of head. What is the sprinkler flow rate in gallons per minute (gpm)? -
correct answer ✔✔7.9 gpm
