BRAE 340 Exam 1 questions n answers
graded A+ updated
How do we measure length? - correct answer ✔✔Miles
How do we measure volume? - correct answer ✔✔ac-in
How do we measure depth? - correct answer ✔✔inches
How do we measure pressure? - correct answer ✔✔head
How do we measure application rate? - correct answer ✔✔in/hr
How do we measure area? - correct answer ✔✔acres
How do we measure power? - correct answer ✔✔Kilowatts
How do we measure velocity? - correct answer ✔✔ft/sec
How do we measure flow rate? - correct answer ✔✔cu-ft/sec
Statements (1) and (2) refer to water requirements. Are these Net of Gross requirements?
(1) The sprinklers must apply 36 inches over the course of the irrigation season.
(2) The vine requires up to 8 gallons of water per day. - correct answer ✔✔1.gross 2.net
,Statements (1) and (2) refer to water requirements. Are these Net of Gross requirements?
(1) Each furrow requires 20 gallons per minute from the syphon tube.
(2) Volume of water pumped for alfalfa was 68 inches per acre. - correct answer ✔✔1.gross
2.gross
An irrigation system applies a gross amount of 42 inches of water during the growing season. An
evaluation determines that: 27 inches goes to satify crop ET; 8 inches runs off and is not
collected for reuse; 4 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 ✔✔Benefical Uses (inches) = Crop ET + Crop Cooling +
Leaching
IE (%) = Benficial IW (in) ÷ Total Applied (in) * 100
The correct answer is: 69.0%
deep percolation is beneficial - correct answer ✔✔false
leaching for salt removal is beneficial - correct answer ✔✔true
Usually, the most significant beneficial use of water is which of the following? - correct answer
✔✔Crop evapotranspiration (ETc)
water used by windbreaks is beneficial - correct answer ✔✔true
Which one of the following is NOT a reason why irrigation in the west usually requires leaching?
- correct answer ✔✔Chemical leaching with soil amendments like gypsum eliminates salt
problems and saves water.
According to some sources, California agriculture uses about 23.9 million acre-feet of water
each year. If the State's population is roughly 33 million, how many gallons per person per day
, does that ag use represent? - correct answer ✔✔million acre-ft/year ÷ million people =
ac-ft/person/year
ac-ft/person/year x 43560 cu-ft/ac-ft = cu-ft/person/year
cu-ft/person/year ÷ 365 days/year = cu-ft/person/day
cu-ft/person/day x 7.48 gallons/cu-ft = gal/person/day
The correct answer is: 646.5
A farmer grows 90 acres of a crop that requires 33 inches (net) of irrigation per year. Water
costs $87 per ac-ft in this area. What would the annual water cost be if the irrigation efficiency
is 73%? - correct answer ✔✔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
The correct answer is: $29497/yr
A pump with a discharge of 17 cfs pumps for 24 hours onto a field of 23.0 acres. What is the
gross depth of irrigation water applied in that time (inches)? - correct answer ✔✔cfs x 60
sec/min x 60 min/hr = cu-ft/hr
cu-ft/hr x hrs ÷ 43560 sq-ft/acre = ac-ft
ac-ft x 12 in/ft ÷ acres = inches
The correct answer is: 17.6
As a rule we say that 1 cfs ≈ 2 ac-ft/day, approximately. The exact converstion factor is really
1.983 ac-ft/day. - correct answer ✔✔true
An elevated water tank is used to feed water into a drip system. How high (ft) must the tank
outlet be in order to cause a 15.4 psi pressure at the inlet of the drip system? - correct answer
✔✔psi x 2.31 ft/psi = ft
graded A+ updated
How do we measure length? - correct answer ✔✔Miles
How do we measure volume? - correct answer ✔✔ac-in
How do we measure depth? - correct answer ✔✔inches
How do we measure pressure? - correct answer ✔✔head
How do we measure application rate? - correct answer ✔✔in/hr
How do we measure area? - correct answer ✔✔acres
How do we measure power? - correct answer ✔✔Kilowatts
How do we measure velocity? - correct answer ✔✔ft/sec
How do we measure flow rate? - correct answer ✔✔cu-ft/sec
Statements (1) and (2) refer to water requirements. Are these Net of Gross requirements?
(1) The sprinklers must apply 36 inches over the course of the irrigation season.
(2) The vine requires up to 8 gallons of water per day. - correct answer ✔✔1.gross 2.net
,Statements (1) and (2) refer to water requirements. Are these Net of Gross requirements?
(1) Each furrow requires 20 gallons per minute from the syphon tube.
(2) Volume of water pumped for alfalfa was 68 inches per acre. - correct answer ✔✔1.gross
2.gross
An irrigation system applies a gross amount of 42 inches of water during the growing season. An
evaluation determines that: 27 inches goes to satify crop ET; 8 inches runs off and is not
collected for reuse; 4 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 ✔✔Benefical Uses (inches) = Crop ET + Crop Cooling +
Leaching
IE (%) = Benficial IW (in) ÷ Total Applied (in) * 100
The correct answer is: 69.0%
deep percolation is beneficial - correct answer ✔✔false
leaching for salt removal is beneficial - correct answer ✔✔true
Usually, the most significant beneficial use of water is which of the following? - correct answer
✔✔Crop evapotranspiration (ETc)
water used by windbreaks is beneficial - correct answer ✔✔true
Which one of the following is NOT a reason why irrigation in the west usually requires leaching?
- correct answer ✔✔Chemical leaching with soil amendments like gypsum eliminates salt
problems and saves water.
According to some sources, California agriculture uses about 23.9 million acre-feet of water
each year. If the State's population is roughly 33 million, how many gallons per person per day
, does that ag use represent? - correct answer ✔✔million acre-ft/year ÷ million people =
ac-ft/person/year
ac-ft/person/year x 43560 cu-ft/ac-ft = cu-ft/person/year
cu-ft/person/year ÷ 365 days/year = cu-ft/person/day
cu-ft/person/day x 7.48 gallons/cu-ft = gal/person/day
The correct answer is: 646.5
A farmer grows 90 acres of a crop that requires 33 inches (net) of irrigation per year. Water
costs $87 per ac-ft in this area. What would the annual water cost be if the irrigation efficiency
is 73%? - correct answer ✔✔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
The correct answer is: $29497/yr
A pump with a discharge of 17 cfs pumps for 24 hours onto a field of 23.0 acres. What is the
gross depth of irrigation water applied in that time (inches)? - correct answer ✔✔cfs x 60
sec/min x 60 min/hr = cu-ft/hr
cu-ft/hr x hrs ÷ 43560 sq-ft/acre = ac-ft
ac-ft x 12 in/ft ÷ acres = inches
The correct answer is: 17.6
As a rule we say that 1 cfs ≈ 2 ac-ft/day, approximately. The exact converstion factor is really
1.983 ac-ft/day. - correct answer ✔✔true
An elevated water tank is used to feed water into a drip system. How high (ft) must the tank
outlet be in order to cause a 15.4 psi pressure at the inlet of the drip system? - correct answer
✔✔psi x 2.31 ft/psi = ft
