Question

In connection with the design of a barrage, identify the correct matching of the criteria of design with the items of design.

Item of design

(i) Width of waterway
(ii) Level and length of downstream floor
(iii) Depth of sheet piles and total length of barrage floor
(iv) Barrage floor thickness

Criteria of design

(A) Scour depth and exit gradient
(B) Lacey's formula for wetted perimeter and discharge capacity of the barrage as computed by weir equations
(C) Uplift pressure variation
(D) Hydraulic jump considerations.

• A. (i) (ii) (iii) (iv)
  A B C D
• B. (i) (ii) (iii) (iv)
  D C B A
• C. (i) (ii) (iii) (iv)
  B A D C
• D. (i) (ii) (iii) (iv)
  B D A C

Answer 1

The correct option is D (i) (ii) (iii) (iv)

B D A C
Width of water way is obtained by Lacey's wetted perimeter formula, given by equation
$P=4.75\sqrt{Q}$
Level and length of the downstream floor is dependent on the characteristics of the hydraulic jump.
Sheet piles must be taken upto the level of scour depth below the bed of the river.
If the uplift pressure is not counteracted by the weight of floor, barrage may fail by rupture.