290 DAM SAFETY: INSTRUMENTATION AND SURVEILLANCE
is to reveal abnormalities in behaviour, and so to provide early warning of
possible distress which may have the potential to develop into a serious
incident or failure. Numbers of instruments installed are of less import-
ance than the selection of appropriate equipment, its proper installation at
critical locations, and intelligent interpretation of the resulting data within
an overall surveillance programme. The effectiveness of the latter is deter-
mined by many factors, including the legislative and administrative frame-
work within which procedures and responsibilities have been established.
The objective of this chapter is to identify parameters of primary
significance to the integrity of dams, and to outline the instrumentation
and techniques employed in surveillance. The chapter includes a review of
alternative philosophies in reservoir safety legislation and of organ-
izational provisions for surveillance and inspection of dams. Recent
publications by the International Commission on Large Dams (ICOLD,
1987, 1988, 1992) provide guidelines on dam safety and monitoring. Issues
regarding dam safety are regularly addressed at ICOLD Congresses and in
principal journals.
Table 7.1 Selected major dam disasters 1959–1993
Dam (year of event) Type, height (m) Event
(Country) (year of completion)
Malpasset (1959) Arch, 61 m (1954) Foundation failure and abutment
(France) yield; total collapse (421 killed)
Vaiont reservoir (1963) Arch, 262 m (1960) Rockslide (200 106 m^3 ) into
(Italy) reservoir; splash-wave 110 m over
dam crest; dam intact (c. 2000
killed)
Teton (1976) Embankment, 93 m Internal erosion from poor
(USA) (completing) cut-off trench design; total
destruction (11 killed, damage
$500 106 )
Macchu II (1979) Embankment and Catastrophic flood; gate
(India) gravity, 26 m (1972) malfunction; overtopping and
embankment washout (estimated
2000 killed)
Tous (1982) Embankment, 127 m Failed by overtopping during
(Spain) (1979) extreme flood event (16 killed,
c.$500 106 damage)
Gouhou (1993) Embankment, 70 m Failure of upstream deck
(China) (1985) leading to local instability and
erosion, with rapid breaching
(c.400 killed)
