Dams and Impounded Rivers - River Dynamics and Integrated River Management - page 423

spillways difficult. Regardless of the types of dam construction and direct causes, when a dam fails, huge
quantities of water rush downstream with great destructive force.
In recent years the failure rate of dams has remained significant while the resulting costs have escalated.
This is due largely to the increasing population of people settling and develop lands downstream from
dams. In a general sense, the seriousness of the threat of dam failure is based on many variables: flash
flooding, inadequate size of spillways, mechanical failure of valves and other equipment, rodent actions in
earthen dams, freezing and thawing cycles, and earthquakes. Old age and neglect can intensify vulnerability
to these same influences.
Table 7.11 The number of dam failure events in several countries and the failure rate, which is defined
as the ratio of the number of dam failures to the number of dams and period of statistics. China, Spain,
and the United States have a high failure rate.

T able 7.11 Number of dam failures and the failure rate in various countries

Number of
dam failures

Number of
dams

Time of
statistics (years)

Rate of dam failure
(1/dam·year)

Country Source

5×10 -4

U.S. Gruner (1963; 1967) 33 1,764 40

3×10 -4 Post-1940 dams 12 3,100 14 U.S.

7×10 -4

U.S. USCOLD (1975) 74 4,914 23

2×10 -4 U.S. U.S. Bureau of Reclamation 1 4,500 1

4×10 -4 U.S. Mark and Stuart-Alexander, 1977 125 7,500 40

2×10 -4 World Middlebrooks, 1953 9 7,833 6

4×10 -5 Japan Takase (1967) 1,046

6×10 -4 Spain Gruner (1967) 150 1,620 145

China Nanking Institute of Water
Resources and Hydro-power

8.65×10 -4 3,462 85,120 47

8.18×10 -4 China IWHR 3,481 85,153 50

Table 7.12 lists numerous dam failure events in several countries. These events occurred mostly in the
1960s and caused casualties of 3 to 3,000 people and economic losses from 1 to 100 million US dollars.
Table 7.13 lists the major dam failure events which have occurred in China. The dam failure events caused
a total death toll of more than 30,000, damaged more than five million houses and more than one million
ha of farmland (He et al., 2008).

Table 7.12 Typical dam failure events and loss of lives and property from countries around the world (Lou, 1981;
H e et al., 2008)

Economic loss
(million dollars)

Dam Country Time of failure Casualties

Puentes Spain 1802-04-30 600 1.0

South Fork U.S. 1889-05-31 2,200 100.0

Saint Francis U.S. 1928-03-13 450 1.5

Veg de Tera Spain 1959-01-10 144

Malpasset France 1959-12 421 (deaths) 68.0

Oros Brazil 1960-03-25 50

Babii Yar USSR 1961-03 145 4.0

Hyokiri North Korea 1961-07 250

Quebrada La Chapa Columbia 1963-04 250