ACA CORRECT FINALS ANSWERS AND QUESTIONS
SET A+
✔✔A floating object travelled a distance of 10m in 9.5 seconds on the average in a
0.5m deep parabolic channel. If the top width is 1.0m the discharge is - ✔✔Answer:
0.3m3/s
✔✔The peak runoff in the mainstream of a watershed has a mean of 128 m3/s and a
standard deviation of 52 m3/s. If the sample data is normally distributed, the magnitude
of runoff corresponding to a probability of exceedance of 16% is - ✔✔Answer: 180 m3/s
✔✔The peak runoff in the mainstream of a watershed has a mean of 128 m3/s and a
standard deviation of 52 m3/s. If the sample data is normally distributed, the magnitude
of runoff corresponding to a probability of exceedance of 16% is - ✔✔Answer: 180 m3/s
✔✔The following infiltration capacity equation has been derived based on experimental
data: f = 10 + 5e-12t where f is in mm/hr and t is in hr. The cumulative infiltration in mm
after 45 minutes is - ✔✔Answer: 7.9 mm
✔✔The velocities at depths of 0.16m and 0.64m in a 0.8m deep and 1.0m wide
rectangular open channel are 1.2m/s and 0.3m/s, respectively. The discharge is. -
✔✔Answer: 0.6m3/s
✔✔A fully penetrating well installed in a confined aquifer with a transmissivity of 197
m2/day is pumped at a constant rate. If the drawdowns in two observation wells 8 m
and 22 m from the pumped well were observed to be 1.42 m and 0.44 m, respectively,
the steady state pump discharge is - ✔✔Answer: 220 gpm
✔✔The velocities at 0.2 and 0.8 of the depth of flow in a parabolic open channel are 1.0
m/s and 0. 2 m/s, respectively. If the flow depth is 0.5 m and the top width is 1.5 m, the
discharge is - ✔✔Answer: 300 lps
,✔✔Given the following direct runoff hydrograph in m3/s taken at 1-hr interval in the
mainstream of a 50 sq. km watershed: 0, 2.8, 13.8, 44.8, 77.8, 37.8, 12.8, 4.5, 1.8, 1.3,
0.9, 0.6, 0.2. The equivalent depth of direct runoff is - ✔✔Answer: 14.3 mm
✔✔A fully penetrating well installed in a confined aquifer with a transmissivity of
197m2/day is pumped at a constant rate. If the drawdowns in two observation wells 8m
and 22m from the pumped well were observed to be 1.42m and 0.44m, respectively the
steady state pump discharge is. - ✔✔Answer: 220gpm
✔✔The peak runoff in a 50 ha-watershed corresponding to a rainfall intensity of 25
mm/hr and a runoff coefficient of 0.8 is - ✔✔Answer: 280 m3/s
✔✔Compute the unidirectional flow in two parallel drains; 1200 m apart if the soil
hydraulic conductivity is 10m/day and the water level at the drains are 7 and 9 meters. -
✔✔Answer: 0.0056 m2/hr
✔✔Compute the land soaking requirement for a soil ( depth of rootzone = 35cm) with
residual moisture content of 15% by mass, bulk density of 1,280 kg/m3 and porosity of
45%. Standing water for planting is 25 mm. - ✔✔Answer: 90.3 mm
✔✔A 25-ft thick confined aquifer with hydraulic conductivity of 500ft/day was tapped by
a 4" shallow tubewell. With a radius of influence of 2000 ft, determine the maximum
discharge of the STW in liters per second. Assume an allowable drawdown of 10 ft. -
✔✔Answer: 27.43
✔✔For an 8m x 8m sprinkler spacing, what is the design sprinkler throw for a 40%
overlap? - ✔✔Answer: 5.6 m
✔✔Determine the design freeboard for a canal with a 100% safety factor for discharge.
The canal bottom width is 1.2 meters and the inverse side slope is 1.75. The design
discharge is 10. 4427 m3/s; roughness coefficient is .015 and the water surface slope is
5x10-3. - ✔✔Answer: 0.58 m
✔✔The 60 cm deep rootzone of a soil has volumetric field capacity and wilting point of
0.345 and 0.236 respectively. Crop consumptive use is 7.2 mm/day. Compute for the
irrigation interval assuming there is 1.7 mm daily rainfall and 80% allowable moisture
depletion. - ✔✔Answer: 9 days
✔✔The critical depth in a rectangular channel with a bottom width of 4.0 m for a
discharge of 5 m3/s is - ✔✔Answer: 0.54 m
✔✔A 30-inch diameter 1-meter long culvert has been designed to carry a maximum
discharge of 1.7 m3/s when flowing half-full. Its roughness coefficient n is 0.014. If the
, inlet and the outlet are both unsubmerged, the difference in elevation between the inlet
and the outlet should be - ✔✔Answer: 5 cm
✔✔What is the depth of water in a trapezoidal channel with a sideslope of 2 and
carrying a 2.5 m3/s water flow? The channel's bottom width is 1.5 meters and the
flowing water has a velocity of 0.8 m/s. - ✔✔Answer: 0.93m
✔✔A concrete-lined trapezoidal canal is to carry a maximum discharge of 2.0 m3/s. The
required head loss over a horizontal distance of 1 km is 2.0 m. The side slope is to be
set at 1:1 and the permissible b/d ratio is 3. If the Manning's roughness coefficient is
0.015, the design depth required is - ✔✔Answer: 0.56 m
✔✔The most hydraulically efficient trapezoidal channel section to carry a discharge of 5
m3/s on a bed material with a roughness n of 0.02 and a bottom slope of 1 in 800
should have a bottom width of - ✔✔Answer: 1.65 m
✔✔The soil has a field capacity of 22% and a permanent wilting point of 12 %, both on
a dry mass basis. The apparent specific gravity is 1.4. If the rootzone depth is 1.0 m and
the management allowable deficit is 50%, the net application depth is - ✔✔Answer: 70
mm
✔✔A 3-ha of cornfield is to be irrigated at a discharge of 250 lps. The average available
water holding capacity is 140 mm/m soil, the management allowable deficit is 40%, and
the rootzone depth is 0.5 m. The reference crop potential evapotranspiration is 5
mm/day and the crop coefficient is 0.8. Assuming 70% application efficiency, the
irrigation period should be - ✔✔Answer: 1 1/3
✔✔The soil has the following characteristics: porosity = 50 %, bulk density = 1.25g/cc,
residual moisture content is 15% dry mass. The rooting depth is 300 mm and the
duration of land soaking is 5 days. If the evaporation and percolation losses amount to 5
mm/day the gross land soaking requirement is - ✔✔Answer: 27.75 mm/day
✔✔How much water should be applied to a 6 ha farm where the rooting depth is 80 cm
if it is in its permanent wilting point? Volumetric moisture contents are 0.15 and 0.32 for
permanent wilting point and field capacity, respectively. - ✔✔Answer: 8,160m3
✔✔Sugarcane is to be irrigated using sprinkler irrigation. The sprinkler spacing is 12.2
m while the lateral spacing is 18.3 m. The soil water holding capacity is 120 mm/m, crop
rooting depth is 1.0 m and management allowable deficit is 45%. If the irrigation period
is 12 hrs and the application efficiency is 70%, the required sprinkler discharge is -
✔✔Answer: 0.4 lps
✔✔Groundwater is to be pumped from a shallow aquifer for irrigation purposes. The
required discharge is 300 gpm. The suction head is 8 ft and the maximum drawdown is
SET A+
✔✔A floating object travelled a distance of 10m in 9.5 seconds on the average in a
0.5m deep parabolic channel. If the top width is 1.0m the discharge is - ✔✔Answer:
0.3m3/s
✔✔The peak runoff in the mainstream of a watershed has a mean of 128 m3/s and a
standard deviation of 52 m3/s. If the sample data is normally distributed, the magnitude
of runoff corresponding to a probability of exceedance of 16% is - ✔✔Answer: 180 m3/s
✔✔The peak runoff in the mainstream of a watershed has a mean of 128 m3/s and a
standard deviation of 52 m3/s. If the sample data is normally distributed, the magnitude
of runoff corresponding to a probability of exceedance of 16% is - ✔✔Answer: 180 m3/s
✔✔The following infiltration capacity equation has been derived based on experimental
data: f = 10 + 5e-12t where f is in mm/hr and t is in hr. The cumulative infiltration in mm
after 45 minutes is - ✔✔Answer: 7.9 mm
✔✔The velocities at depths of 0.16m and 0.64m in a 0.8m deep and 1.0m wide
rectangular open channel are 1.2m/s and 0.3m/s, respectively. The discharge is. -
✔✔Answer: 0.6m3/s
✔✔A fully penetrating well installed in a confined aquifer with a transmissivity of 197
m2/day is pumped at a constant rate. If the drawdowns in two observation wells 8 m
and 22 m from the pumped well were observed to be 1.42 m and 0.44 m, respectively,
the steady state pump discharge is - ✔✔Answer: 220 gpm
✔✔The velocities at 0.2 and 0.8 of the depth of flow in a parabolic open channel are 1.0
m/s and 0. 2 m/s, respectively. If the flow depth is 0.5 m and the top width is 1.5 m, the
discharge is - ✔✔Answer: 300 lps
,✔✔Given the following direct runoff hydrograph in m3/s taken at 1-hr interval in the
mainstream of a 50 sq. km watershed: 0, 2.8, 13.8, 44.8, 77.8, 37.8, 12.8, 4.5, 1.8, 1.3,
0.9, 0.6, 0.2. The equivalent depth of direct runoff is - ✔✔Answer: 14.3 mm
✔✔A fully penetrating well installed in a confined aquifer with a transmissivity of
197m2/day is pumped at a constant rate. If the drawdowns in two observation wells 8m
and 22m from the pumped well were observed to be 1.42m and 0.44m, respectively the
steady state pump discharge is. - ✔✔Answer: 220gpm
✔✔The peak runoff in a 50 ha-watershed corresponding to a rainfall intensity of 25
mm/hr and a runoff coefficient of 0.8 is - ✔✔Answer: 280 m3/s
✔✔Compute the unidirectional flow in two parallel drains; 1200 m apart if the soil
hydraulic conductivity is 10m/day and the water level at the drains are 7 and 9 meters. -
✔✔Answer: 0.0056 m2/hr
✔✔Compute the land soaking requirement for a soil ( depth of rootzone = 35cm) with
residual moisture content of 15% by mass, bulk density of 1,280 kg/m3 and porosity of
45%. Standing water for planting is 25 mm. - ✔✔Answer: 90.3 mm
✔✔A 25-ft thick confined aquifer with hydraulic conductivity of 500ft/day was tapped by
a 4" shallow tubewell. With a radius of influence of 2000 ft, determine the maximum
discharge of the STW in liters per second. Assume an allowable drawdown of 10 ft. -
✔✔Answer: 27.43
✔✔For an 8m x 8m sprinkler spacing, what is the design sprinkler throw for a 40%
overlap? - ✔✔Answer: 5.6 m
✔✔Determine the design freeboard for a canal with a 100% safety factor for discharge.
The canal bottom width is 1.2 meters and the inverse side slope is 1.75. The design
discharge is 10. 4427 m3/s; roughness coefficient is .015 and the water surface slope is
5x10-3. - ✔✔Answer: 0.58 m
✔✔The 60 cm deep rootzone of a soil has volumetric field capacity and wilting point of
0.345 and 0.236 respectively. Crop consumptive use is 7.2 mm/day. Compute for the
irrigation interval assuming there is 1.7 mm daily rainfall and 80% allowable moisture
depletion. - ✔✔Answer: 9 days
✔✔The critical depth in a rectangular channel with a bottom width of 4.0 m for a
discharge of 5 m3/s is - ✔✔Answer: 0.54 m
✔✔A 30-inch diameter 1-meter long culvert has been designed to carry a maximum
discharge of 1.7 m3/s when flowing half-full. Its roughness coefficient n is 0.014. If the
, inlet and the outlet are both unsubmerged, the difference in elevation between the inlet
and the outlet should be - ✔✔Answer: 5 cm
✔✔What is the depth of water in a trapezoidal channel with a sideslope of 2 and
carrying a 2.5 m3/s water flow? The channel's bottom width is 1.5 meters and the
flowing water has a velocity of 0.8 m/s. - ✔✔Answer: 0.93m
✔✔A concrete-lined trapezoidal canal is to carry a maximum discharge of 2.0 m3/s. The
required head loss over a horizontal distance of 1 km is 2.0 m. The side slope is to be
set at 1:1 and the permissible b/d ratio is 3. If the Manning's roughness coefficient is
0.015, the design depth required is - ✔✔Answer: 0.56 m
✔✔The most hydraulically efficient trapezoidal channel section to carry a discharge of 5
m3/s on a bed material with a roughness n of 0.02 and a bottom slope of 1 in 800
should have a bottom width of - ✔✔Answer: 1.65 m
✔✔The soil has a field capacity of 22% and a permanent wilting point of 12 %, both on
a dry mass basis. The apparent specific gravity is 1.4. If the rootzone depth is 1.0 m and
the management allowable deficit is 50%, the net application depth is - ✔✔Answer: 70
mm
✔✔A 3-ha of cornfield is to be irrigated at a discharge of 250 lps. The average available
water holding capacity is 140 mm/m soil, the management allowable deficit is 40%, and
the rootzone depth is 0.5 m. The reference crop potential evapotranspiration is 5
mm/day and the crop coefficient is 0.8. Assuming 70% application efficiency, the
irrigation period should be - ✔✔Answer: 1 1/3
✔✔The soil has the following characteristics: porosity = 50 %, bulk density = 1.25g/cc,
residual moisture content is 15% dry mass. The rooting depth is 300 mm and the
duration of land soaking is 5 days. If the evaporation and percolation losses amount to 5
mm/day the gross land soaking requirement is - ✔✔Answer: 27.75 mm/day
✔✔How much water should be applied to a 6 ha farm where the rooting depth is 80 cm
if it is in its permanent wilting point? Volumetric moisture contents are 0.15 and 0.32 for
permanent wilting point and field capacity, respectively. - ✔✔Answer: 8,160m3
✔✔Sugarcane is to be irrigated using sprinkler irrigation. The sprinkler spacing is 12.2
m while the lateral spacing is 18.3 m. The soil water holding capacity is 120 mm/m, crop
rooting depth is 1.0 m and management allowable deficit is 45%. If the irrigation period
is 12 hrs and the application efficiency is 70%, the required sprinkler discharge is -
✔✔Answer: 0.4 lps
✔✔Groundwater is to be pumped from a shallow aquifer for irrigation purposes. The
required discharge is 300 gpm. The suction head is 8 ft and the maximum drawdown is
