/ Jun 15, 2025

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Understanding Dam Failures: Causes and Historical Incidents

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Dam failures, which can manifest as a complete collapse of the structure or partial scouring, occur for a variety of reasons. An analysis of historical dam failures indicates that one or more of the following factors often contribute to such catastrophic events:

  1. Prolonged rainfall and floods
  2. Insufficient spillway capacity
  3. Internal erosion leading to piping and seepage
  4. Inadequate maintenance of dam equipment during operation
  5. Use of unsuitable design or materials
  6. Landslides causing water to overtop the dam body
  7. Failure of another dam located upstream in the dam basin
  8. Terrorist attacks
  9. Earthquakes causing cracks along the upper section of the dam body
  10. Excessive inflow into the dam reservoir
  11. Insufficient or incorrect selection of filter material
  12. Human, design, and computational errors.

The causes of dam failures can be broadly categorized into three main groups:

a) Water Overtopping the Dam Crest

Water overtopping the dam body can occur for several reasons but is most commonly due to inadequate spillway capacity. It can also happen if the spillway, even if adequately sized, becomes blocked by solid materials. The water flowing over the dam crest can then cause erosion, ultimately leading to the dam’s failure.

b) Foundation Failures

Foundation failures leading to dam collapse can stem from the inherent characteristics of the foundation soil or rock, as well as from improper improvement works carried out during construction. Differential settlement, cracks, and water seepage can be indicators of foundation problems. Furthermore, the incorrect selection and application of foundation materials during the design phase can lead to serious issues.

c) Piping in the Dam Body

In embankment dams, voids can form over time within the impermeable zone (core) designed to prevent seepage. This occurs when seeping water carries away fine material. These voids can act like pipes, and as water flows through them, they can enlarge, eventually causing the dam to fail. This phenomenon is known as piping.

Dam Collapse Events in History

Dam Year Country Deaths Cause of Collapse
1 Banqiao/Shimantan 1975 China 171 000 Cadastrophic precipitation
2 Machchu 2 1979 India 5 000 Water overflow from the top
3 Sempor 1967 Indonesia >2 000 Water overflow from the top
4 South Fork 1889 USA 2 209 Excessive rainfall
5 Vajont 1963 Italy 2 000 Water overflow from the top
6 Tigıa 1917 India 1 000 Water seepage into the foundation
7 Panshet 1961 India 1 000 Collapse of dam body
8 Puentes 1802 Spain 608 Soft ground
9 St. Fıasncis 1928 USA 600 Geological insensitivity
10 Malpesset 1959 France 423 During the construction phase
11 Gleno 1923 Italy 356 Poor design and construction
12 Val di Stava 1985 Italy 268 Poor design and construction
13 Koshi 2008 Nepal 250 Excessive rainfall
14 Dale Dike 1864 England 244 Poor design and construction
15 Canyon Lake 1972 ABD 238 Flood
16 Kantale 1986 Sri Lanka 180 Flawed operation
17 Tangiwai 1953 New Zealand 151 Crater lake overflow
18 Bouzey 1884 Algeria 150 Slippage
19 Vega de Tera 1959 Spain 144 Collapse of dam body
20 Mili Nehri 1874 USA 139 Defective design
21 Buffalo Creek 1972 USA 125 Excessive rainfall
22 Sella Zerbino 1935 Italy 111 Flood
23 Vratsa 1966 Bulgaria 107 Flood
24 Situ Gintung 2009 Indonesia 98 Excessive rainfall
25 Certej 1971 Romania 89 Defective design
26 Bilberry 1852 England 81 Turbine rupture
27 Austin 1911 USA 78 Intentional destruction
28 Sayam/Shushenskaya 2009 Russia 75 Excessive rainfall
29 Shajidor 2005 Pakistan 70 Excessive rainfall

 

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