Notches are devices used to measure the flow rate of liquids through channels. Notches are classified based on their shape as rectangular, triangular, or trapezoidal. Rectangular notches offer more pressure drop than other shapes. Flow through rectangular and trapezoidal notches depends on the upstream depth, while flow through triangular notches depends on the notch angle. Triangular notches are useful for measuring low flow rates. Trapezoidal notches have discharge equal to the sum of a rectangular and two triangular notches. Weirs are larger structures used to store and measure large river and canal flows, while notches are smaller devices that measure small stream or canal flows.

1. WHAT ARE NOTCHES AND
THEIRS TYPES

2. INTRODUCTION
A notch is a device used for measuring the rate of
flow of a liquid through a small channel or tank .
Due to notches the pressure energy of liquid is
converted into kinetic energy.

3. Classification of notches
The notches are classified as:
 According to the shape of opening
1. Rectangular notch
2. Triangular notch
3. Trapezoidal notch

4. Rectangular notch
 A rectangular shaped notch that is usually installed at the end of
upstream It Offers more pressure drop.
 Flow rate in rectangular notch is dependent on the depth of
upstream
 The equation of discharge over the rectangular notch
Q= 2/3.Cd.L.√(2g).H^(3/2)

5. Triangular notch
Often called as a v notch. Useful for measuring low flow rate . Pressure
loss is recovered.
The equation of discharge over the Triangular notch is given by
Q=8/15.Cd.√(2g).Tan(ᶿ/2).H^(5/2)

6. Trapezoidal notch
 It is the combination of rectangular notch and the two triangular
notch
 Discharge over the trapezoidal notch will be the sum of discharge
of rectangular notch and triangular notch
 Discharge over the trapezoidal notch is given as
Q=2/3.Cd.L.√(2g).H^(3/2)+8/15.Cd.√(2g).Tan(ᶿ/2).H^(5/2)

7. DIFFERENCE BETWEEN NOTCHES
AND WIRE
NOTCH
1. A notch may be defined as an opening
provided in one side of a tank or reservoir,
with u/s liquid level below the top edge of
the opening.
2. The bottom edge of notch over which water
flows is known as sill or crest.
3. A notch is usually made of a metallic plate
4. A notch is used to measure small discharge of
small stream or canal.
5. Notches are of small size.
WIER
1. A weir may be defined as a
structure constructed across a river
or canal to store water on the
upstream side
2. The top of the weir over which
water flows is known as crest.
3. A weir is made of cement concrete
or masonary.
4. A weir is used to measure large
discharge of rivers and large canals.
5. Weirsd are of bigger size.

8. GROUP MEMBERS
NAME REG#
USAMA PERVAIZ FA16-CHE-114
MUHAMMAD SHABAN FA16-CHE-074
AWAIS AHMED FA16-CHE-61
MUHAMMAD JHANZAIB FA16-CHE-112
MUHAMMAD BILAL FA16-CHE-039
MUHAMMAD UZAIR FA16-CHE- 37