30
3 Examples of Recent Catastrophic Hydro-Dam Accidents
dams had flood discharges (weirs? gates? pennstocks?), nor why only one was the
object of emergency manoeuvres. We also do not know at this stage what part of the
project was still under construction, as commercial operations had not started yet.
Were the dams finished and filled, but the generating plants still under construction?
Monday 12:00—The Lao PDR government orders villagers downstream to evacuate
after learning that there could be further damage to the dam.
Monday 18:00—More damage is confirmed at the dam.
3.2.3 Consequences
The consequences are unfortunately of tragic proportion. The accident resulted in the
flooding of eight villages: Ban Mai; Ban HinLath; Ban ThaSengchan; Ban Thahintai;
Ban Sanong; Ban Thae; Ban Phonsa-ath; Ban Nongkhae. The Lao PDR government
declared the affected areas as National Disaster Areas. On July 24 response activities
were reportedly still underway and UN agencies continued to gather information and
assess the impacts (UN OCHA 2018).
The collapse of the dam reportedly affected nearly 7000 people and displaced
more than 1000. Many houses were damaged, forcing people to seek shelter in local
government buildings and schools. Red Cross teams in the Attapeu branch distributed
clothing, food and drinking water to households in the affected areas (IFRC/Lao Red
Cross 2018).
3.2.4 Risk-Related Concepts
As we have done in the aftermath of other catastrophic failures, we will not discuss
responsibilities or faults but focus instead on a few risk-related concepts.
Lao PDR is hit by frequent tropical storms and cyclones.
1 We do not know if
there is a climate change trend developing at this time, but these events are far from
a surprise in Lao PDR. Tropical cyclones are not direct hazards, since their force is
normally diminished (reaching tropical storm level) once they reach Lao PDR from
the South China Sea. However, they can produce flooding as a consequence of heavy
rainfall. Up to three cyclones hit the country annually (UNISDR et al. 2018).
We do not know how many failures there might have been in the country over
the course of its history, nor how many dam-years
2 the country actually has. If
we consider a round number of 50 hydro projects, at this time we had 1/50 failures. Combining this with a frequency of major tropical storm of, let’s say, 1/10,
we have p f = 1/10/50 = 1/500 (or 0.002, see horizontal line in Fig. 3.4). If we
look at historical hydro-dams failure rate of 10
−4 –10
−5 (1/10,000–1/100,000) and
1 The difference between tropical storm and cyclone lies in the wind speed.
2 Normally expressed as the product of the number of dams by the years in existence.
3 Examples of Recent Catastrophic Hydro-Dam Accidents
dams had flood discharges (weirs? gates? pennstocks?), nor why only one was the
object of emergency manoeuvres. We also do not know at this stage what part of the
project was still under construction, as commercial operations had not started yet.
Were the dams finished and filled, but the generating plants still under construction?
Monday 12:00—The Lao PDR government orders villagers downstream to evacuate
after learning that there could be further damage to the dam.
Monday 18:00—More damage is confirmed at the dam.
3.2.3 Consequences
The consequences are unfortunately of tragic proportion. The accident resulted in the
flooding of eight villages: Ban Mai; Ban HinLath; Ban ThaSengchan; Ban Thahintai;
Ban Sanong; Ban Thae; Ban Phonsa-ath; Ban Nongkhae. The Lao PDR government
declared the affected areas as National Disaster Areas. On July 24 response activities
were reportedly still underway and UN agencies continued to gather information and
assess the impacts (UN OCHA 2018).
The collapse of the dam reportedly affected nearly 7000 people and displaced
more than 1000. Many houses were damaged, forcing people to seek shelter in local
government buildings and schools. Red Cross teams in the Attapeu branch distributed
clothing, food and drinking water to households in the affected areas (IFRC/Lao Red
Cross 2018).
3.2.4 Risk-Related Concepts
As we have done in the aftermath of other catastrophic failures, we will not discuss
responsibilities or faults but focus instead on a few risk-related concepts.
Lao PDR is hit by frequent tropical storms and cyclones.
1 We do not know if
there is a climate change trend developing at this time, but these events are far from
a surprise in Lao PDR. Tropical cyclones are not direct hazards, since their force is
normally diminished (reaching tropical storm level) once they reach Lao PDR from
the South China Sea. However, they can produce flooding as a consequence of heavy
rainfall. Up to three cyclones hit the country annually (UNISDR et al. 2018).
We do not know how many failures there might have been in the country over
the course of its history, nor how many dam-years
2 the country actually has. If
we consider a round number of 50 hydro projects, at this time we had 1/50 failures. Combining this with a frequency of major tropical storm of, let’s say, 1/10,
we have p f = 1/10/50 = 1/500 (or 0.002, see horizontal line in Fig. 3.4). If we
look at historical hydro-dams failure rate of 10
−4 –10
−5 (1/10,000–1/100,000) and
1 The difference between tropical storm and cyclone lies in the wind speed.
2 Normally expressed as the product of the number of dams by the years in existence.