hydrology and water resource engineer Reservoir capacity, Reservoir sedimentation and control

1. CIVIL ENGG.DEPARTMENT
BIRLA VISHVAKARAMA MAHAVIDYALAYA ENGG. COLLEGE
VALLABH VIDYANAGAR-388120
B.TECH-CIVIL ENGINEERING
TOPIC -Reservoir capacity, Reservoir sedimentation
and control
Subject – Hydrology and water resources Engineering
Subject code : 2150602
FACULTY GUIDE-
Pro. H.V. Patel Dhaval Parmar Sir
Assistant professor Adhok trainee assistant professor
Department of Civil Engineering
PREPARED BY : SAGAR SHAH
Id. No. : 17CE335

2. Contents:-
 Introduction
 Reservoir capacity
 Reservoir Sedimentation
 Types of sediment
 Causes of sedimentation
 Reservoir sedimentation control

3. Introduction:-
what is a Reservoir ?
It is an area developed by water
body due to construction of dam.

4. Reservoir capacity:-
Depends upon the inflow available
and demand.
Inflow in the river is always greater
than the demand, there is no storage
required.
If the inflow n the river is small but
the demand is high, a large reservoir
capacity is required.

5. The required capacity for a reservoir
can be determined by the following
methods:-
1) Graphical method, using mass
curves.
2) Analytical method

6. Reservoir sedimentation:-
 All rivers carry certain amount of water of
sedimentation which is produced due to
erosion in their catchment areas.
 These sediments are deposited in the
reservoir on the upstream of the dam
because of reduction of velocity.
 Sedimentation reduce the available
capacity of the reservoir.
 Continuous sedimentation, the useful life
of the reservoir goes on decreasing.

7.  If the soil in the catchment is loose and erodible,
the sediment load is large.
 In case of catchments having steep slopes, the
sediment load is large because of high velocity of
water.
 If the catchment area has no vegetal cover, the
soil is easily eroded and the sediment load is
large.
 If the intensity of rainfall is high, the discharge in
the river is increased and the sediment load is
large.

8. Type of sediment
The sediment load carried by a river
may be divided into the following two
parts:-
1. Suspended load
2. Bed load

9. The suspended load is that part of
the sediment load which does not
move in contact with the bed of
the river.
It consists of relatively finer
materials.
Suspended load

10. The bed load is that part of the
sediment load which moves in
contact with the bed of the river.
It consists of relatively coarser
materials.
Bed load

11. Causes of sedimentation
 Nature of soil in the catchment area
 Vegetation cover in the catchment area
 Topography of the catchment area
 Intensity of rainfall
 Cultivation of land

13. Density currents:-
 Density current may be defined as a flow
of one fluid under another fluid of a
slightly different density under the effect
of gravity.
 In may reservoir density current are
usually developed, especially during flood
when rivers carry heavily sediment- laden
or muddy water.

14. Measurement of sediment load:-
 The suspended sediment load of a stream
is measured by taking the samples of
water at various depths.
 The samples are weighted and filtered to
remove the sediment.
 The sediment is then dried and weighted.
 The sediment load is expressed in ppm
(parts per million)

15. Sediment load

16. Trap efficiency:-
 Trap efficiency is defined as the percentage
of the sediment deposited in the reservoir
even inspite of taking precautions and
measures to control its deposition.

17. Reservoir sedimentation control :-
In order to increase the useful life
of a reservoir, the rate of
deposition of sediments in the
reservoir should be decreased.

18. Precautions of sedimentation control
 Selection of suitable site
 Proper design
 Control of sediment inflow
a) check dam b) vegetation screens
 Control of sediment deposition
 Removal of sediment deposits
 Soil conservation