The document discusses three types of flood routing: mechanical, electric analog, and digital. Mechanical routers include the integrating flood router which uses five drum charts to plot input and output hydrographs. The rolling flood router uses an undercarriage to move over an inflow hydrograph. Electric analog routers make analogies between hydrologic variables and electric circuits. Digital computers simplify routing with programs that can quickly compute outflows. The document also discusses various canal lining materials including cement concrete, shotcrete, soil cement, asphaltic concrete, brick, earth, and bentonite. It provides details on their composition and suitable applications. Finally, it presents a design problem to calculate dimensions for a triangular concrete-lined channel given discharge, slope

1. ASSIGNMENT
(CE4003)
WATER RESOURCES ENGINEERING-II
SUBMITTED BY:
BHAG CHAND MEENA
B120915CE
A-CIVIL
19/11/2015

2. Q.1
FLOOD ROUTING MACHINES-
This is the third type of flood routing. Here we’ll discuss-
1. Mechanical flood routers
2. Electric analog routing machine
3. Digital computers
1. Mechanical Flood Routers-
There are a number of machines developed for routing
floods through reservoirs or channels. The integrating flood router developed by J.F.tarpley
(1939) consists of five drum mounted graph charts driven continuously by motor
arrangement. In three drums input data like inflow hydrograph, elevation-discharge and
elevation-storage curved are fed as input graph charts, whereas the rest two drums plot time-
elevation and time-outflow graph continuously while routing is in operation. To read input
data from three drums, pointers are kept in position touching the graph or charts. To plot the
output graph pen pointer are attached to last two drums say it (4) & (5). Movement of the
pointers, drums and pens are synchronised such that as the drum rotates all the five pointers
move, the two output graphs are automatically plotted. The machine needs to be calibrated to
fit the given system.
The rolling type mechanical flood router developed by F.B. Harkness (1951) of U.S. Army
corps of engineers is used for channel routing where Muskingum method is used with time
step of ∆𝑡 = 2𝐾𝑋. In this instrument, an undercarriage with wheel, pen and pointer
arrangement moves over the plotted inflow hydrograph.

3. 2. Electric Analog, Routing Machine-
Such a routing machine was developed by U.S>
Weather Bureau (1955) in which the inflow, outflow and storage of water is made
analogous with that of electric current. A condenser capable of storing current is made
analogous to storage S. The inflow I and outflow O from a reservoir or channel is
made similar to inflow and outflow of current from the condenser. The routing
equation in channel is analogous to electric circuit. By such a machine, variation of
storage with time constant K value can be incorporated. With the addition of an
oscilloscope and other electronic devices, the instrument can be made more handy,
accurate and fast. At several flood forecasting sites, routing is carried out by such
machines.
3. Digital Computers-
With the advent of digital computers, the problem of routing has
become much simplified. A unique computer program can be written for the system
of channel or reservoir for routing various inflow hydrographs. The program can be
verified from the knowledge of previous inflow-outflow hydrographs. Once the
program is validated, it takes a few seconds to compute the outflow hydrograph from
the information of the inflow hydrograph. Large number of watershed simulation
models have been developed which takes into account the rainfall, meteorological,
parameters an basin characteristics as input data, computes a unit hydrograph,
convolutes it its rainfall excess hyetograph to obtain flood hydrograph and routes the
flood hydrograph through the channel or reservoir giving directly the outflow for the
system. Use of telemetry gauges in a basin and validated computer program at the
desired site of the river makes the process quick and accurate.
Q.2
MATERIALS FOR CANAL LINING-
Canal lining is the process of reducing seepage loss
of irrigation water by adding an impermeable layer to the edges of the trench. Seepage can
result in losses of 30 to 50 per cent of irrigation water from canals, so adding lining can make
irrigation systems more important. Some of lining materials can be listed as follows.
1. Cement Concrete
The in situ concrete lining is one of the most conventional type of lining which has
successfully been used in India and other parts of the world. Cement concrete lining is more
preferable than any other lining where channel is to carry high velocity water because of its
greater resistance to erosion. Velocities up to 2.5 m/sec are generally considered permissible
with adequate water depth although higher velocities up to 5.0 m/sec in case of Kosi Feeder
Channel in U.P. have been provided. Cement concrete lining eliminates weed growth and
thereby improves flow characteristics. Provision of concrete lining reduces maintenance

4. charges to a minimum. Frequent cracks due to contraction taking place from temperature
change, drying and shrinkage and settlement of sub-grade. It is also likely to be damaged
from alkaline water. Cement concrete lining without reinforcement may be damaged due to
excessive external water pressure. The reinforced concrete lining can withstand the external
water pressure but at a very high cost. When unexpected water pressures are encountered, un-
reinforced lining will crack more easily than the reinforced lining and will relieve the
pressure thereby reducing the area of damage.
2. Shot Crete
Spacing In this type of lining cement mortar is applied by pneumatic pressure. The
lining may be considered with or without reinforcement (in the form of mesh or expanded
metal), although reinforcement (in the form of mesh or expanded metal), although
reinforcement increases its useful life, especially, when laid over earth sub-grade. Since the
thickness of lining is limited to 5.0 cm mostly such linings are applied on smaller channels or
where operational requirements are not severe.
3. Soil Cement
This type of lining is made up of a mixture of cement and natural sandy soil. This type
of lining may sometimes result in considerable saving as compared to cement concrete lining.
It is not weather-resistant.
4. Asphaltic Concrete
Asphaltic concrete has greater ability to withstand changes in the subgrade. Asphaltic
concrete lining can be used for repairing cement concrete lining by placing a resurfacing
layer of asphaltic concrete. Velocities for this lining are limited to 1.5 m/s. Weed growth
results in puncturing of lining; sliding during hot season.
5. Brick lining
This type of lining has been extensively used in India and elsewhere. This type of
lining is economical where aggregates for concrete lining are not available.

5. 6. Earth Linings
Thick compacted earth lining is durable and can withstand considerable external hydrostatic
pressure. Bentonite has shown considerable promise for use as a good lining material.
Bentonite containing large percentage of Montmorillonite, is characterised by high water
absorption accompanied by swelling and imperviousness. It can be used as 5 cm thick
membrane covered by protective blanket or as a mixed in place layer of soil Bentonite and
well compacted.
Q.3 Design a triangular shaped concrete line channel for a discharge of 27 m3/s at
a slope of 25cm/km. Side slope of channel is 1.5:1 and n = 0.016.
Limiting velocity = v Depth = h
S = 2.5x10-4 Width = b
Q = 27 m3/s
n = 0.016
m = 1.5
* tan 𝜃 = 1/m = h/(b/2) b = 2 h m = 3 h 𝜃
* A = ½ b h = 1.5 h2
* v = Q/A = 27/(1.5 h2) = 18/h2
* Pw = 2√ℎ2 + (1.5ℎ)2 = √13 h
* R = A/Pw = 1.5 h/√13
* v = (1/n) Rh
2/3 S1/2
18/h2 = (1/0.016) (1.5 h /√13)2/3 (2.5x10-4)1/2
h = 3.697 ≅ 3.7 m
𝜃
h
b
1
m

6. Answers: h = 3.7 m
b = 3 h = 11.1 m
Pw = √ 𝟏𝟑 h = 40 m
v = 18/h2 = 1.31 m/s