Dam Breaks: Causes, Consequences, and Historical Catastrophes

Understanding Dam Breaks and Reservoir Failures

What is a Dam or Reservoir?

A dam is a wall made of stone, concrete, or loose materials, usually built in a canyon over a river, stream, or canal. Its primary purpose is to contain water in the riverbed for later use, such as:

• Water supply and irrigation.
• Production of mechanical energy (transforming potential energy into kinetic energy).
• Electricity generation (hydropower).
• Flood control by containing heavy rainfall.

Primary Causes of Dam Failures

Dam breaks often result from a combination of structural and environmental factors:

• Poor Location: Construction in geologically unstable or unsuitable areas.
• Defective Construction: Poor engineering or inadequate resistance.
• Material Quality: Use of defective or substandard materials.
• Hydrological Stress: Overtopping due to extreme rainfall (e.g., cold drops).
• Operational Failures: Malfunctions in control systems, such as inability to open sluices.

Devastating Consequences

The rupture of a dam results in catastrophic floods, causing extensive damage:

• Loss of human life and displacement of populations.
• Widespread destruction of infrastructure and property.
• Severe environmental damage, including toxic spills (as seen in mining dams).

Prevention and Safety Measures

Effective prevention relies on rigorous planning and continuous monitoring:

• Safe Construction: Building the dam in a secure area using materials suitable for storing large amounts of water.
• Monitoring: Efficiently controlling and monitoring the water level in the reservoir.
• Alert Systems: Implementing an effective system to alert and evacuate the population quickly in case of imminent failure.

Major Dam Failure Incidents

Case Studies in Spain

Ribadelago Disaster (1959)

The town of Ribadelago, belonging to the municipality of Galende (Zamora), suffered the catastrophic failure of the Vega de Tera Dam on January 9, 1959. The dam, located high in the surrounding mountains, suddenly broke, flooding the town which then had about 500 inhabitants. This tragedy resulted in the deaths of 144 people. The incident forced the refounding of the town within the Natural Park of Lago de Sanabria.

Aznalcóllar Mining Spill (1998)

On April 25, 1998, a dam break occurred at the pyrite mine in Aznalcóllar (Seville). This resulted in a massive discharge of highly toxic acid water and sludge, causing extremely serious environmental consequences for the region. The spill flowed onto the banks of the Agrio and Guadiamar rivers, though fortunately, it did not reach the nearby Natural Park of Doñana.

Tous Dam Rupture (1982)

The rupture of the Tous Dam (Alicante) occurred on October 20, 1982, following a severe weather event known as a "cold drop" that caused intense rainfall and severe flooding across the Valencian Community. A series of operational failures prevented the sluices of the dam from being opened. As the reservoir filled rapidly, the structure eventually broke down and burst. The resulting wave of water exacerbated the flooding in areas already affected by the rains, leading to the deaths of 12 people.

International Dam Failure Incidents

• Jakarta, Indonesia (2009)

  In March 2009, 58 people drowned and dozens disappeared when a dam on the outskirts of Jakarta broke, flooding a neighborhood of the capital. Rescue efforts were slow and complicated due to the extensive amount of mud and debris.

• Buffalo Creek, USA (1972)

  On February 26, 1972, a rupture occurred in one of three dams constructed of loose material in the State of West Virginia (Buffalo Creek). The collapse released 500 million liters of water, causing devastating flooding in the towns along Buffalo Creek, resulting in the deaths of 125 people and leaving thousands homeless.

Reservoir Sedimentation (Clogging)

A reservoir clogs when it is filled by the deposition of material (sediment) transported by water. As this process occurs, the reservoir gradually loses its intended water storage capacity, impacting its functionality and lifespan.