Engineering Hydraulics Lab

TITLE:
To Develop Relationship between
Surface Area, Elevation & Capacity
of the Reservoir

DESIGN # 1
ENGINEERING HYDRAULICS

SUBMITTED TO
Sir Usman Ali
SUBMITTED BY:
Zaib-Un-Nisa
2015-Civ-02

Department of Civil Engineering 2015-CIV-02

 Engineering Hydraulics Lab 1

TABLE OF CONTENTS

PROBLEM STATEMENT: ________________________________________________________________ 2

Required Data: __________________________________________________________ 2

Given Data: ____________________________________________________________ 2

RELATED THEORY: ____________________________________________________________________ 3

Reservoir: ______________________________________________________________ 3
Classification of Reservoirs: ________________________________________________ 3
1. Impounding or Storage Reservoirs _______________________________________ 3
2. Flood Control Reservoirs: _____________________________________________ 3
3. Retarding Reservoirs: _________________________________________________ 3
5. Distribution Reservoirs _______________________________________________ 3
Storage Capacity of Reservoirs: ______________________________________________ 3
Benefits of Reservoir: _____________________________________________________ 4
Disadvantages of Storage: __________________________________________________ 4
Components of Reservoir: __________________________________________________ 4
Area-Elevation Curve: _____________________________________________________ 4
Elevation-Capacity Curve __________________________________________________ 5
Surface Area-Volume Curve: ________________________________________________ 5
Elevation and Capacity Curve: _______________________________________________ 6
Rule Curve: ____________________________________________________________ 6
Practical Importance of Curves: ______________________________________________ 6

PROCEDURE:__________________________________________________________________________ 6
CALCULATIONS: ______________________________________________________________________ 0
RESERVOIR CURVES: __________________________________________________________________ 8

1. Area-Elevation Curves: ______________________________________________ 8

2. Capacity-Elevation Curve: ____________________________________________ 8
3. Area-Capacity Curve: _______________________________________________ 9
4. Area-Capacity-Elevation Curve: _______________________________________ 9

RESULTS: ____________________________________________________________________________ 10
COMMENTS: _________________________________________________________________________ 10
REFERENCES: ________________________________________________________________________ 10

Department of Civil Engineering 2015-CIV-02

 Engineering Hydraulics Lab 2
DESIGN JOB # 1

PROBLEM STATEMENT:
For the following set of data relating to a reservoir, develop the following required curves
Required Data:
1. Elevation Vs. Surface area Curve
2. Elevation Vs. Capacity Curve
3. Surface Area Vs. Capacity Curve
Given Data:
Longitudinal Section:

H4
1:350

H3
1:300

H2
1:150

H1 1:100

R/10 R/12 R/15 R/12

(Km) (Km) (Km) (Km)

Cross-Section:

H3+ H4
1:10

H2
1:8

H1 1:5

80 m

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RELATED THEORY:
Reservoir:
It is an area developed or occupied by water body due to presence of a dam or barrier across the river.
Classification of Reservoirs:
1. Impounding or Storage Reservoirs:
Storage reservoirs are also called conservation reservoirs because they are used to conserve water.
Storage reservoirs are constructed to store the water in the rainy season and to release it later when the
river flow is low.
2. Flood Control Reservoirs:
A flood control reservoir is constructed for the purpose of flood control. It protects the areas lying on
its downstream side from the damages due to flood.
3. Retarding Reservoirs:
A retarding reservoir is provided with spillways and sluiceways, which are ungated. The retarding
reservoir stores a portion of the flood when the flood is rising and releases it later when the flood is
receding.
4. Detention Reservoirs:
A detention reservoir stores excess water during floods and releases it after the flood. It is similar to a
storage reservoir but is provided with large gated spillways and sluiceways to permit flexibility of
operation.
5. Distribution Reservoirs:
A distribution reservoir is a small storage reservoir to tie over the peak demand of water for municipal
water supply or irrigation. The distribution reservoir is helpful in permitting the pumps to work at a
uniform rate. It stores water during the period of lean demand and supplies the same during the period
of high demand.
6. Multipurpose Reservoirs:
These are constructed for more than single purpose
7. Balancing Reservoirs:
A balancing reservoir is a small reservoir constructed d/s of the main reservoir for holding water released
from the main reservoir.
Storage Capacity of Reservoirs:
 Whatever may be the use of a reservoir, its most important function is to store water during floods
and to release it later.
 The storage capacity of a reservoir is, therefore, its most important characteristics.

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 Engineering Hydraulics Lab 4
 The available storage capacity of a reservoir depends upon the topography of the site and the
height of dam.
 To determine the available storage capacity of a reservoir up to a certain level of water,
engineering surveys are usually conducted.
 The storage capacity and the water spread area at different elevations can be determined from the
contour map
Benefits of Reservoir:
 Reservoirs provide many benefits including water supply, floodwater control, power generation,
irrigation and recreational use.
 Barrier for migratory animals like fishes
 Decreasing flow volumes in tail waters
 Stabilization of flow regimes by flood peak cut
 River bed degradation and increase in substrate grain size by sediment trapping, etc.
Disadvantages of Storage:
 Creating a reservoir can flood existing settlements

 Eroded material is deposited in the reservoir and not along the rivers natural course so farmland
downstream can be less fertile

 A careful management of reservoir is required

 Storage bridges sediments & if more storage is retained for a longer time then a time will come
when all the storage capacity of reservoir is lost

Components of Reservoir:
The main components of the reservoir are
1. Elevation of reservoir
2. Surface Area of reservoir
3. Capacity of Reservoir

Area-Elevation Curve:
From the contour plan, the water spread area of the reservoir at any elevation is determined by measuring
the area enclosed by the corresponding contour. Generally, a planimeter is used for measuring the area.
An elevation-area curve is then drawn between the surface area as abscissa and the elevation as ordinate.

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Fig.1: Area Elevation Curve

Elevation-Capacity Curve
The storage capacity of the reservoir at any elevation is determined from the water spread area at various
elevations. An elevation storage volume is plotted between the storage volume as abscissa and the
elevation as ordinate. Generally, the volume is calculated in Mm3 or M-ha m.

Fig.2: Storage Elevation Curve

Surface Area-Volume Curve:

It is plotted between the surface area and volume. Through this curve, we come to know that how much
area will be under water for a specific volume of the reservoir.

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 Engineering Hydraulics Lab 6

Fig.3: Storage Area Curve

Elevation and Capacity Curve:
It relates the head and Capacity, as head increased capacity of reservoir increases.
Rule Curve:
The Curve between the reservoir water level and time is known as rule curve of a reservoir. The rule
curve divides the storage volume of a reservoir in zones where different strategies for demand supply
will be applied. The limits of each zone may vary seasonally or remain constant during the whole year.
Such tool may be used for flood control or water conservation during long dry spells
Practical Importance of Curves:
 Before the Construction of the dam, these curves are used to decide the most appropriate site for
construction.

 After construction of dam, these are used to determine various reservoir factors.

 They give the idea of land to be acquire & number of people to be migrated for the construction
of the reservoir.

PROCEDURE:
 For the longitudinal and cross-section of the reservoir, a detailed survey is to be carried out to
determine the side slopes and longitudinal or bed slopes.
 From the longitudinal slopes, calculate the height of the reservoir and from the cross sectional
slopes calculate the cross sectional areas.
 By selecting a suitable interval, find out the mean surface area and mean capacity for the different
strips.
 Plot the Elevation-Surface area curve, Capacity-Elevation Curve and Capacity-Surface Area
Curve.
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 Engineering Hydraulics Lab 7

CALCULATIONS:
STORAGE CAPACITY OF A RESERVOIR
Sr. # Height Interval L-section X-Section Mean Surface Mean Volume Cumulative mean
Area Capacity of Every Volume
Segment
z1 z2 Bottom top Average Bottom top Average
m m m m m m m m m m2 m3 m3
1 0 0.2 0.2 0 20 10 100 102 101 1010 202 202
2 0.2 0.4 0.2 20 40 30 102 104 103 3090 618 820
3 0.4 0.6 0.2 40 60 50 104 106 105 5250 1050 1870
4 0.6 0.8 0.2 60 80 70 106 108 107 7490 1498 3368
5 0.8 1 0.2 80 100 90 108 110 109 9810 1962 5330
6 1 1.2 0.2 100 120 110 110 112 111 12210 2442 7772
7 1.2 1.4 0.2 120 140 130 112 114 113 14690 2938 10710
8 1.4 1.6 0.2 140 160 150 114 116 115 17250 3450 14160
9 1.6 1.8 0.2 160 180 170 116 118 117 19890 3978 18138
10 1.8 2 0.2 180 200 190 118 120 119 22610 4522 22660
11 2 2.2 0.2 200 230 215 120 123.2 121.6 26144 5228.8 27888.8
12 2.2 2.4 0.2 230 260 245 123.2 126.4 124.8 30576 6115.2 34004
13 2.4 2.6 0.2 260 290 275 126.4 129.6 128 35200 7040 41044
14 2.6 2.8 0.2 290 320 305 129.6 132.8 131.2 40016 8003.2 49047.2
15 2.8 3 0.2 320 350 335 132.8 136 134.4 45024 9004.8 58052
16 3 3.1 0.1 350 365 357.5 136 137.6 136.8 48906 4890.6 62942.6
17 3.1 3.3 0.2 365 425 395 137.6 141.6 139.6 55142 11028.4 73971
18 3.3 3.5 0.2 425 485 455 141.6 145.6 143.6 65338 13067.6 87038.6
19 3.5 3.7 0.2 485 555 520 145.6 149.6 147.6 76752 15350.4 102389
20 3.7 3.9 0.2 555 625 590 149.6 153.6 151.6 89444 17888.8 120277.8
21 3.9 4.026 0.126 625 669.1 647.05 153.6 156.12 154.86 100202.16 12625.47 132903.27

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 Engineering Hydraulics Lab 8

RESERVOIR CURVES:
1. Area-Elevation Curves:

Area-Elevation Curve
4.5
4
3.5
3
Elevation (m)

2.5 y = -5E-10x2 + 8E-05x + 0.2461

2
1.5
1
0.5
0
0 20000 40000 60000 80000 100000 120000
Surface Area (m2)

2. Capacity-Elevation Curve:

Capacity-Elevation Curve
4.5
4
3.5
3
Elevation (m)

y = -2E-10x2 + 6E-05x + 0.6407

2.5
2
1.5
1
0.5
0
0 20000 40000 60000 80000 100000 120000 140000
Capacity (m3)

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 Engineering Hydraulics Lab 9

3. Area-Capacity Curve:

Area-Capacity Curve
120000

100000
Surface Area(m2)

80000
y = -8E-08x2 + 0.7127x + 5174.4

60000

40000

20000

0
0 20000 40000 60000 80000 100000 120000 140000
Capacity (m3)

4. Area-Capacity-Elevation Curve:

Area-Capacity-Elevation Curve
Surface Area (m2)
120000 100000 80000 60000 40000 20000 0
4.5

3.5
Elevation (m)

2.5

1.5

0.5

0
0 20000 40000 60000 80000 100000 120000 140000
Capacity (m3)

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 Engineering Hydraulics Lab 10

RESULTS:
 The Mean height of the given reservoir is 4.026m

 The Mean surface area of the given reservoir is 100200 m2 = 0.100200 Mm2

 The top surface area of the given reservoir is 104460 m2 = 0.104460 Mm2

 The Total Mean Capacity of the given reservoir is 132900 m3 = 0.132900 Mm3

 The relationship between Surface Area(A) & Elevation(H) for this reservoir is given by the
following relation:

H = -5E-10A2 + 8E-05A + 0.2461

 The relationship between Capacity(V) & Elevation(H) for this reservoir is given by the
following relation:

H = -2E-10V2 + 6E-05V + 0.6407

 The relationship between Capacity(V) & Surface Area(A) for this reservoir is given by the
following relation:

A = -8E-08V2 + 0.7127V + 5174.4

COMMENTS:
 Importance of storage vs area curve is that we can find the area, which will be under water at a
particular storage.
 Similarly, with storage elevation curve, we can find the elevation at any storage and will be
able to decide the height of the dam, location of the spillways etc.
 These curves are equally important before, during and after the construction of the reservoir.

REFERENCES:
1. http://www.scielo.br/scielo.php?script=sci_arttext&pid=S2318-03312016000300493
2. https://getrevising.co.uk/grids/dams_and_reservoirs
3. Class Notes
4. Fluid Mechanics with Engineering Application by Daugherty

Department of Civil Engineering 2015-CIV-02