surface water sources

7/27/2019 Surface Water Sources

1/5

1/21/20

SURFACE WATER SOURCES

STORAGE RESERVOIRS

Dr. Sanghamitra Kundu

Types

Storage or conservation reservoirs

Flood protection reservoirs

Distribution reservoirs

Multipurpose reservoirs

2

Various kinds of dams3

Earth dams

Rock-fill dams

Solid masonry gravity dams

Hollow masonry gravity dams

Steel dams

Timber dams

Arch dams

4

Green mountain dam, Colorado, USANagarjuna Sagar Dam, AP, India

Bhakra Dam


2/5

1/21/20

Rockfill dam (Cougar Dam, USA)5

Arch Dam6

Idukki Dam, Kerala

Investigations for reservoir planning7

Engineering surveys

Preparation of contour plan

Area elevation curve

Storage elevation curve

Map of the area to indicate the land and property to be

surveyed

Suitable site selection for the dam

8

Geological investigations

Water tightness of the reservoir basin

Suitability of foundations for the dam

Geological and structural features, such as folds, faults,fissures etc., of the rocks of the basin

Type and depth of overburden (superficial deposits)

Location of permeable and soluble rocks, if any

Ground water conditions in the region

Location of quarry sites for materials required for damconstruction, and quantities available from them

Investigations for reservoir planning


3/5

1/21/20

9

Hydrological investigations

Study of run-off pattern at the proposed dam site to

determine the availability of water

Determination of the hydrograph of the worst flood, to

determine the spillway capacity and design

Investigations for reservoir planning Selection of site for a reservoir10

Catchment area: Percolation losses are minimum, maximum run-off

Reservoir basin should be narrow For economy, the length of the dam should be less

Site should be such that a deep reservoir is formed Lower cost of land submerged per unit of capacity

Less evaporation losses because of reduction in the water spreadarea

Less likelihood of weed growth

Site should be easily accessible

Value of land and property submerged by the proposedreservoir should be as low as possible

Storage zones of a reservoir11

Normal pool level or Maximum conservation level

Minimum pool level

Useful and dead storage

Maximum pool level

Surcharge storage

Bank storage

Valley storage

Storage capacity of a reservoir12

The monthly inflow rates during a low water period atthe site of a proposed dam are tabulated in the giventable. The corresponding monthly pan evaporation andprecipitation at a nearby station are also given in thetable. Prior water rights make it obligatory to releasethe full natural flow or 15 ha-m/month, whichever isminimum. If the estimated monthly demands are given inthe table and the net increased pool area is 400 ha,find the required storage capacity of the reservoir.Assume pan evaporation coefficient=0.7 and alsoassume that only 28% of the rainfall on the land area

to be flooded by the reservoir has reached the streamin the past.


4/5

1/21/20

13

Month

Inflow at the

dam site in ha-

m

Pan

evaporation in

cm

Precipitation in

cm

Demand

in ha-m

January 1.2 1.8 1.3 15.8

February 0 1.8 1.7 14.3

March 0 2.6 0.6 9.6

April 0 10.2 0 4.8

May 0 15.4 0 3.5

June 0 16.6 1.1 3.4

July 240 10.8 16.1 5

August 480 11.7 16.4 5

September 1 10.8 2.2 10

October 0.6 9.6 0.8 15.6

November 0.5 7.8 0 16.8

December 0.2 2 0 16.8

723.5 101.1 40.2 120.6

14

Plot the mass inflow curve

Plot the demand curve

From the apices of the mass inflow curve draw

tangents parallel to the demand curve

Measure the vertical intercepts between the tangent

and the mass curve

The biggest of the vertical ordinates represent the

reservoir capacity

Storage capacity of a reservoir(Ripple Method)

15

Find the required storage capacity of a reservoir

for the data given below. The draft is uniform with

16 Ml/month.

Storage capacity of a reservoir16

Procedure for determining the minimum storage capacityof a reservoir (for no shortage of draft)

Based on the assumption that the reservoir is full at thebeginning of the dry period. Denote monthly run-off as Q, and Monthly demand as D

Find the deficiency for each value = (D-Q)

Negative values are surplus, positive values are deficiencies

Calculate the cumulative deficiency (D-Q), by startingcumulation at the beginning of the maximum dry period

The required maximum storage is the highest numerical value

in (D-Q) values or the maximum cumulative deficiency atthe end of the dry period.

Storage capacity of a reservoir

(Sequent Peak Procedure)


5/5

1/21/20

Distribution Reservoir17

A distribution reservoir is to be constructed for

supplying water to a city. Water is pumped from

wells to the distribution reservoir at a uniform rate

of 2.5 cumecs. The estimated hourly requirements

for the maximum day are tabulated below. Estimate

the capacity of the distribution reservoir.

surface water sources

Documents