When a dam is broken or destroyed, a substantial volume of water is released abruptly in the form of a flood wave, which is likely to cause catastrophic damage to life and property downstream and to have a negative impact on the downstream ecology and ecosystem. Dam failure can also cause death due to drowning or being hit by flying debris.
The force of the water can be very large, depending on several factors such as: the height of the dam, the type of construction used, etc. The resulting flood can cause considerable damage even far away from the actual site of the dam, for example by eroding the riverbed and causing landslides.
The release of water into a cave or mine shaft may also cause serious damage and loss of life due to flooding or cave-in, respectively.
In addition, severe floods can cause power outages by removing cables from their poles or destroying substations. After the flood has subsided, restoration of electricity often requires significant work by trained engineers.
Finally, dams serve a vital role in preventing floods and other natural disasters. Without them many areas would be submerged during high tides or storm surges.
Dam failure can be caused by natural processes such as an earthquake or landslide, or by human activity such as bombing raids or sabotage.
Dam collapses or levee breaches can happen fast and unexpectedly, creating significant flash floods in the surrounding region and inflicting property damage and loss of life. Significant Risk: Dam failure might result in some fatalities and property damage.
A dam collapse is called an event without precedence. It is considered a major incident that requires rapid response by multiple agencies with special expertise. Damage caused by dams is estimated at more than $1 billion per year. Many factors can lead to their failure, such as heavy rainfall, overloading, poor design, and vandalism.
Levees are banks of earth or concrete built across streams to protect settlements from flooding. They can be either temporary or permanent. Temporary levees are usually made out of dirt or sand dumped into areas likely to flood and then stabilized with grass or shrubs. Permanent levees are constructed of rock or concrete and cannot be moved if needed to protect against new threats. They generally provide better protection against larger flows but may not be suitable for certain locations. Flood control is the main purpose for building both temporary and permanent dams. They can also be used for power generation. Dams can cause flooding by blocking the flow of water into lakes or rivers.
A dam failure, often known as a dam burst, is a catastrophic form of failure that is defined by the abrupt, fast, and uncontrolled release of impounded water, or the possibility of such an uncontrolled release. Dam collapses are uncommon, but when they occur, they may inflict massive damage and loss of life. Dam failures are usually due to severe erosion caused by heavy rain or snow melt, which can weaken the foundation of the dam. The resulting flood may be large enough to cause more damage than the initial problem that led to building the dam in the first place.
The severity of the damage depends on many factors such as how much water is released in a short period of time, the location of the dam, and the type of dam construction. Some dams require substantial rainfall before they fail while others have been shown to fail even without any precipitation at all.
Dams serve two main purposes: storage and diversion. Storage dams hold water for periods longer than it would otherwise flow naturally from its source to its estuary or other body of water. This stored water is then available for use during times of need, such as flooding areas downstream or irrigation. Diversion dams perform the opposite function of moving water from one point to another. One example of a diversion dam is the Hoover Dam on the Colorado River. It controls the amount of water flowing into Lake Mead behind it and regulates its own power production depending on the needs of users downriver.
Flooding may be disastrous if a dam along a reservoir fails. High water levels have also forced a number of tiny dams to fail, spreading devastation downstream. A levee in one spot may simply send high water up or downstream, causing floods. But when a large portion of land is covered by just one kind of soil, even a small breach can lead to major flooding.
When a dam fails, it can cause devastating floods. The walls of the dam break down, causing the water behind it to rush through the gap and flood the area behind it. Dam failures can be caused by heavy rainfall upstream, but they also can be due to human activity. Sometimes roads cross streams where people build houses without any consideration of how much rain might fall in different parts of the country. This can lead to problems later when those areas need to be flooded for agriculture or industry.
Dam failures can be very dangerous if you're not careful. When a dam breaks, all its power goes into draining the lake behind it away. This means that if someone is in the way when the dam gives out, they could be killed or at least swept away.
The damage from flooding is often estimated based on the cost of repairing or replacing damaged infrastructure. However, economic losses due to flooding are actually a lot larger than this because they include losses such as reduced property value, litigation costs, and deaths.
Flooding and habitat destruction: dammed rivers form a reservoir upstream of the dam, which pours over into the surrounding environment and destroys ecosystems and habitats that once existed there. Flooding has the potential to destroy or displace a wide range of creatures, including plants, wildlife, and humans. Dam construction can also have other negative effects. For example, large-scale deforestation may be required in order to build reservoirs, causing environmental damage in its own right.
Loss of biodiversity: many species are endangered because they are dependent on specific biological resources (such as water or energy) that remain stable only within certain limits. When these resources are depleted through flooding or other means, so are the species that depend on them. Dam construction often leads to the extinction of some species, either directly through loss of life or indirectly through changes to the environment that make it difficult for them to survive.
Economic losses: people often benefit from maintaining natural environments because they provide food, fuel, fiber, and other products that are useful to humans. When forests are cut down or waters are diverted away from their usual routes, these benefits are lost. The financial cost of this activity is called the "damaging effect" or "social impact" of dams, and it usually exceeds the economic benefit derived from electricity production.
Political controversy: large dams receive widespread opposition from environmentalists and others who view them as threats to aquatic ecosystems and local cultures that rely on stable water supplies.