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WorksheetsDay 32-Oct 21-worksheet-Diploma-Notches&weirs
Total questions: 15
Worksheet time: 11mins
In a suppressed rectangular weir, ventilation beneath the nappe is essential primarily to
Increase crest length
Reduce velocity of approach
Avoid negative pressures below nappe
none
For a triangular notch, discharge sensitivity with respect to head measurement is high because
Q ∝ H²
Q ∝ H3/2
Q ∝ H5/2
Q ∝ H0.5
The main hydraulic reason for providing bevelled upstream edges in sharp-crested weirs is to
Increase coefficient of discharge
Promote uniform overflow
Avoid clinging of nappe
Reduce approach velocity
In stepped notches, increase in total discharge takes place mainly due to
Progressive submergence of lower steps
Successive triangular contributions
Incremental rectangular areas at each stage
none
In a triangular weir, a small percentage error in head measurement produces a larger percentage error in discharge compared to a rectangular weir.
True
False
Suppressed weirs do not require ventilation of nappe since there is no contraction.
True
False
Assertion (A): Ventilation holes are provided on the downstream side of a suppressed rectangular weir. Reason (R): They ensure continuous atmospheric air supply beneath the nappe to prevent vacuum formation.
A and R are true; R is the correct explanation
A and R are true; R is NOT the correct explanation
A is true but R is false
A is false but R is true
The sheet of water flowing over the crest of a weir is called (a) .
In a trapezoidal (Cipolletti) weir, the side slopes are provided to eliminate the effect of (a) .
The ……… of a weir is the top surface over which flow takes place.
(a)
When the downstream water level rises above the crest of a weir, it is termed as (a) weir.
A broad-crested weir carries maximum discharge when the depth of water over crest h equals (a) .
The effective crest length in a contracted rectangular weir reduces by…………..on each side
(a)
Match the following
Ogee weir
Spillway of storage dams
Broad-crested weir
Medium discharge measurement
Cipolletti weir
Avoid end contraction in gauging
Sharp-crested weir
Small irrigation channels
Match the following
Suppressed notch
Full opening across channel
Contracted notch
Crest length < channel width
Triangular notch
Used for low discharge, accurate gauging
Stepped notch
Provided for uniform crest length
