The document discusses the possibility of dam failures from several causes. It notes that overtopping, piping, foundation failures, and structural issues can lead to dam breaches. Changes in land use, weather patterns, outdated designs, lack of maintenance, and large flood events exceeding spillway capacity also contribute to failures. Two examples of dam failures in India are provided: the Kaddam Project dam in Andhra Pradesh failed in 1958 due to overtopping, and the Machhu II dam in Gujarat failed in 1979 because flood flows greatly exceeded its spillway capacity.

1. POSSIBILITY
OF
DAM FAILURES
Submitted to: Submitted By:
Dr. Ankit Sahai AMOL AGARWAL
Asst. Prof 144122
Mechanical

2. DAMS
 A dam is a barrier across flowing water
that obstructs, directs or slows down the
flow, often creating a reservoir, lake or
impoundments.
 Most dams have a section called
a spillway or weir over which, or through
which, water flows, either intermittently or
continuously, and some have hydroelectric
power generation systems installed.

3. SPILLWAY
 A spillway is a structure used to provide the
controlled release of flows from
a dam or levee into a downstream area,
typically being the river that was dammed.
 Spillways release floods so that the water
does not overtop and damage or even
destroy the dam.
 Except during flood periods, water does not
normally flow over a spillway.

4. DAM FAILURE
 Dams are generally an
expensive structure that directly
affect the economy of the area
through power generation, flood
control and water supply
(reservoirs). As the population
of an area grows, structural
failure of a large dam due to an
earthquake poses an
increasingly great danger for
residents exposed to sudden
flooding.
 Failure of dam across the Kern
River following the 1952 Kern
County Earthquake

5. MAIN CAUSES

6. OVERTOPPING
 Overtopping of a dam, as shown, is often a
precursor of dam failure. National statistics
show that overtopping due to inadequate
spillway design, debris blockage of spillways,
or settlement of the dam crest account for
approximately 34% of all U.S. dam failures.

8. PIPING
 Another 20% of U.S. dam failures have been
caused by piping (internal erosion caused by
seepage). Seepage often occurs around
hydraulic structures, such as pipes and
spillways; through animal burrows; around
roots of woody vegetation; and through
cracks in dams, dam appurtenances, and
dam foundations.

10. LOCATION AND GEOLOGY
 Poor dam siting (ex: Teton
1976) and poor engineering
(ex: Banqiao 1975) can be
key contributing factors in
failures.
 Geological events like
landslides (ex: Vajont 1963)
and earthquakes
(ex: Fujinuma 2011) are in
rare instances associated with
dam failure, but the historic
record is dominated dams
successfully weathering
earthquakes, landslides, and
reservoir tsunamis.
 Vajont Dam after the
Landslide

11. FOUNDATION FAILURE
 The foundations of any dam can be
compromised, and this is one of the most feared
and dangerous types of dam failure.
 Concrete arches have in some cases ruptured
suddenly. Notably, Malpasset arch dam in
France suddenly broke from its foundations in
1959 during a heavy rainstorm, killing 421
people.
 Foundation failure is believed to have caused
the dam to collapse, but no witnesses survived
the event.

12. OTHER CAUSES
 Structural failure of
materials used in dam
construction
 Earthquakes
 Sliding of a mountain into
the reservoir

13. HIDDEN CAUSES

14. CHANGES IN LAND USE
 The most important factor in whether a dam will
fail is the amount of water that it has to hold
back, Dams are designed and built based on the
state of the watershed at the time.
 So when the landscape is changed, it can have a
big impact on how quickly water is absorbed into
the ground or runs off, toward the dam.
 A dam near homes in Columbia is overtopped by
flooding on October 6.

15. CHANGES IN WEATHER PATTERNS
 Shifting weather patterns can also put more
strain on dams, as some areas get wetter
while others get drier.
 The engineering community is working on
this problem, but right now we don’t have
good models that tell us how much to adjust
our plans based on changing climate,” says
France.

16. OUTDATED DESIGNS
 Dam design has also improved over the past
century, although many communities can’t afford
to replace their old dams with the latest
technology.
 Newer earthen dams, for instance, are built with
the filter design, which puts progressively
coarser material toward the interior of the walls.
 That allows a small amount of water to seep into
the dam but prevents the smaller grains from
moving with it, locking them in place.

17. LACK OF MAINTENANCE AND FUNDING
 Unlike roads, which are largely paid for with
a regular excise tax on gasoline, dams have
historically had more haphazard funding.
 Another problem is the rising number of
orphan dams, which no longer serve a useful
purpose and often end up in a state of
disrepair.

18. DAM FAILURES IN INDIA

19. KADDAM PROJECT DAM, ANDHRA PRADESH
 The dam was overtopped by 46 cm of water
above the crest, inspite of a free board
allowance of 2.4 m that was provided,
causing a major breach of 137.2 m wide that
occurred on the left bank.
 Two more breaches developed on the right
section of the dam. The dam failed in August
1958.

20. MACHHU II (IRRIGATION SCHEME) DAM, GUJARAT
 The dam failed on August 1, 1979,
because of abnormal floods and
inadequate spillway capacity.
 The spillway capacity provided for 5663
m³/s. The actual observed flow following
the intense rainfall reached 16307 m³/s,
thrice what the dam was designed for,
resulting in its collapse.

21. THANK YOU
FOR YOUR
PATIENCE !!