Department of Civil Engineering Institute of Technology, GGV

B.Tech. Third Year [VIth

Sem.]

Subject: Water Resources Engineering –I

Subject Code: CE32T04

Maximum Marks: 60 Note: (i) Section-A, all questions carry equal marks. 02 Marks allotted for each question.

(ii) Section-B, Attempt any one question from each Unit. All question carry equal Marks.

SECTION – A Q(1) One cumec day is equal to

(a) 8.64 hectare-m (b) 8.60 hectare-m

(c) 8.46 hectare-m (d) 8.40 hectare-m

Q(2) ) Disadvantages of irrigation

(a) It may reduce crop yield (b)It is expensive and complex. (c)

Over irrigation may lead to water logging (d) all of the above

Q(3) Classification of canals based on nature of source of supply

(a) Permanant canal (b) Productive canal

(c) Protective canal (d) Feeder canal

Q(4) According to the Lacey’s theory Velocity V is given by

(a) V=[Qf2/140]

1/6 (b) V=[Qf

2/140]

1/4 (c) V=[Qf

2/140]

1/3 (d) V=[Qf

2/140]

1/2

Q(5) Water logging is controlled by

(a) Control of intensity of irrigation (b) Economic use of water

(c) Fixing of crop pattern (d) all of the above

Q(6) Q(6) For small channels lining is recommended.

(a) short crete lining (b) soil-cement lining (c) Brick lining (d) Concrete lining

Q(7) Levees are constructed

(a) parallel to river flow (b) perpendicular to river flow

(c) inclined to river flow (d) None of the above

Q(8) In which stage meander is form

(a) delta stage of river (b) boulder stage of river

(c) trough stage of river (d) in all stages

Q(9) Safe yield is defined as

(a) Maximum quantity of water available in dry period

(b) Maximum quantity of water available in flood period

(c) Minimum quantity of water available in dry period

(d) Minimum quantity of water available in flood period

Q(10) Silting of reservoir

(a) To reduce the efficiency of dam (b) To raises the reservoir level

(c) To reduce the storage capacity (d) To increase the storage capacity

SECTION – B

Unit-I Q-1 (a) What are the factors affecting duty? (08 Marks)

OR

(b) Discuss in brief flooding methods for irrigation. (08 Marks)

1

Unit-II Q-2 (a) ) Discuss in brief classification of irrigation canal. (08 Marks)

2(a)

2(a)

2(a)

2(b)

2©

2(b) 2©

OR

(b) Design an irrigation canal with the following data

(i) Discharge of the canal = 24 m3/sec

(ii) Pemissisible mean velocity = 0.80 m/ sec

(iii) Bed slope = 1 in 5000.

(iv) Side slope = 1: 1

(v) Chezy’s constant, C = 44

(08 Marks)

2(d) 2(d)

D=2.09, B=18.18-2.83x 2.09

B= 12.27 m

Unit-III Q-3 (a) Discuss in brief surface drainage and it importance for water logging.

(08 Marks)

Surface drainage is often achieved by land forming and smoothing to remove isolated

depressions, or by constructing parallel ditches. Ditches and furrow bottoms are gently graded

and discharge into main drains at the field boundary. Although the ditches or furrows are

intended primarily to convey excess surface runoff, there is some seepage through the soil to the

ditches, depending on the water table position. This could be regarded as a form of shallow

subsurface drainage. Surface drainage is especially important in humid regions on flat lands with

limited hydraulic gradients to nearby rivers or other disposal points. There is also a need for

good surface drainage in semi-arid regions which are affected by monsoons.

Drainage

It is the process of removal of excess water as free or gravitational water from the surface and

the sub surface of farm lands with a view to avoid water logging and creates favourable soil

conditions for optimum plant growth.

Need for drainage

It is generally assumed that in arid region drainage is not necessary and water

logging is not a problem. Even in arid region due to over irrigation and seepage from

reservoirs canals etc., drainage becomes necessary.

Irrigation and drainage are complementary practices in arid region to have

optimum soil water balance.

In humid region drainage is of greater necessity mainly due to heavy

precipitation.

Drainage is required under the following condition

a) High water table

b) Water ponding on the surface for longer periods

c) Excessive soil moisture content above F.C, not draining easily as in clay soil

d) Areas of salinity and alkalinity where annual evaporation exceeds rainfall and

capillary rise of ground water occurs

e) Humid region with continuous of intermittent heavy rainfall

f) Flat land with fine texture soil

g) Low lying flat areas surrounded by hills

Characteristics of good drainage system

1. It should be permanent

2. It must have adequate capacity to drain the area completely

3. There should be minimum interference with cultural operated

4. There should be minimum loss of cultivable area

5. It should intercept or collect water and remove it quickly within shorter period

Methods of drainage

There are two methods

1. Surface method

2. Sub surface method

Surface drainage

This is designed primarily to remove excess water from the surface of soil profile.

This can be done by developing slope in the land so that excess water drains by gravity.

It is suitable for

(i) Slowly permeable clay and shallow soil

(ii) Regions of high intensity rainfall

(iii) To fields where adequate out lets are not available

(iv) The land with less than 1.5% slope

It can be made by

a) Land smoothing

b) Making field ditches

The surface drainage can be further classified as

a) Life drainage

b) Gravity drainage

c) Field surface drainage

d) Ditch drainage

Lift drainage

To drain from low lying area or areas having water due to embankment, life drainage is used.

Water to be drained is lifted normally by opened devices unscoops or by pumping or by

mechanical means. This method is costly, cumbersome and time consuming but effective and

efficient to drain standing water over the soil surface.

Gravity drainage

Water is allowed to drain from the areas under higher elevation to lower reaches through the

regulated gravity flow through the out let of various types. This system is practiced in wet land

rice with gentle to moderate slope. This method is less costly, easy and effective however the

area to be drained should be leveled smooth and slightly elevated from the drainage source.

Field surface drainage

The excess water received from the rain or irrigation is drained through this method. The

irrigated basins or furrows are connected with the drainage under lower elevation

which is connected to the main out let and to the farm pond used for water harvesting. If the

slope of the land is sufficient to drain excess water from the individual plot, this drain water

may be collected and stored locally in reservoir for recycling for life saving irrigation. This

drainage method is cheap and effective but there is possibility of soil erosion and distribution of

weed seeds along the flow of drainage water.

OR

(b) Designed a lined canal for 250 m3/sec discharge, side slope 1.25: 1, bed slope 1 in 6666

Manning’s N= 0.018 and Permissible velocity = 1.75 m/sec.

(08 Marks)

Unit-IV Q-4 (a) What is the necessity of river training works?

(08 Marks)

OR

(b) Explain in brief importance for Flood Control and structures used for it.

(08 Marks)

3.0

3.0

Fig. 3.0

Figure (a) Diversion and Link Channel Figure (b) Cut Off

Unit-V Q-5 (a) Discuss in brief Type of reservoirs.

(08 Marks)

OR

(b) Discuss the inflow storage discharge method of Flood Routing.

(08 Marks)

Methods of flood routing depend on a knowledge of storage in the reach :

Two ways :

1. make a detailed topographical and hydrographical survey of the river reach and the land and

so determine the storage capacity of the channel at different levels.

2. use the records of past levels of flood waves at the two points and hence deduce the reach's

storage capacity.

As many data as possible are required for the second method, which is the one generally used,

including flow records at the beginning and end of the reach and on any tributary streams

joining it, and rainfall records over any areas contributing direct runoff to it.

Storage in the reach of a river is divided into two parts, prism and wedge storage, which are

illustrated in Figure This is simply because the slope of the surface is not uniform during floods,

Figure Storage in a river Reach

If the continuity of flow through the reach shown in Figure is considered, it is clear that what enters the

reach at point a must emerge at point B, or temporarily move into storage.

dS

I = D + -----

dt

where : I = inflow to the reach, D = discharge from the reach, dS/dt = rate of change in reach

storage with respect to time.

This equation is approximated, for a time interval t, by :

(I1+I2) t/2- (D1+D2) t/2 = S1-S2

The time t is called the routing period and it must be chosen sufficiently short so that the

assumption implicit in equation (a). In particular, if t is too long it is possible to miss the peak

of the inflow curve, so the period should be kept shorter than the travel time of the flood

wave crest through the reach, On the other hand, the shorter the routing period the greater the

amount of computation to be done

Reservoir routing

If equation is now arranged so that all known terms are on one, the expression: The routing

process consists of inserting the known values to obtain (S2 + ½ D2t) and then deducing the

corresponding value of (D2) from the relationship connecting storage and discharge.

The simplest case is that of a reservoir receiving inflow at one end and discharging through a

spillway at the other. In such a reservoir it is assumed, there is no wedge storage and that the

discharge is a function of the surface elevation, provided t that spillway arrangements are

either free-overflow or gated with fixed gate openings. Reservoirs with sluices can be treated

also as simple reservoirs if the sluices ate opened to defined openings at specified surface-

water levels, so that an elevation-discharge curve can be drawn. The other required data are

the elevation-storage curve of the reservoir and the inflow hydrograph