Dam failures – a system error of water resources management
In recent years, accidents have become more frequent at hydraulic structures that have been operating for more than 30-50 years. The risk of accidents increases with changes in the properties of materials. The presence of a large number of dams gives the problem of safe operation a huge social, economic and environmental significance.
The destruction of the dam can cause extremely negative consequences for the economy and the environment, and the damage can exceed the cost of construction. The probability of dam accidents begins to increase steadily when structures are older than 50 years. Over the past 100 years, there have been more than 1 thousand accidents at large hydraulic structures in the world, with the main reason being the destruction of the Foundation and insufficient capacity of the spillway, which causes water to overflow over the dam's crest.
On May 1 of this year, a dam burst in Uzbekistan, affecting residents of Uzbekistan and southern Kazakhstan [1]. Two countries have declared a state of emergency. Residents of flooded areas were evacuated to safe areas. A special Commission is investigating the causes of accidents (figure 1).
Figure 1-Erosion of the dam of the reservoir of the Sardobinsky district of the Syrdarya region of Uzbekistan
The Deltares center, an independent Institute for applied research on water resources and subsurface resources, based in Delft and Utrecht (the Netherlands), analyzed the condition of the Sardobin reservoir and justified the dam break as an overflow of water due to a large amount of precipitation, wind waves or internal erosion of pipes. Dutch experts say that a dam break may also be (in part) due to possible design or construction errors, as well as a lack of proper monitoring and maintenance. They noted that the analysis they presented is preliminary, and a more thorough study of the issue is required to fully investigate the causes of the rock-earth dam breach and assess the consequences, involving additional information, including data on the dam design, construction method, construction materials used, conditions, infrastructure, and so on [2].
The following accidents occurred on May 19 in the United States: two dams - Edenville and Sanford in Michigan were destroyed as a result of prolonged precipitation (figure 2).
Figure 2 - A dam break in Michigan.
In the flood zone was Midland, a city of 42,000 people, which is located 8 miles downstream from the Sanford dam. Figure 2 clearly shows that the water began to overflow over the ridge and washed away the body of the dam. Catastrophic water consumption is caused by heavy precipitation for several days. The overflow of water over the crest of the dam is explained by the unsatisfactory operation of the spillways, which is confirmed by figure 3. The analysis of the 2019 floods showed major problems in water management and infrastructure, with losses from flooding amounting to $ 20 billion [3].
Figure 3 - Water overflow over the dam.
The disasters cited in Uzbekistan and the United States are manifestations of a large-scale phenomenon associated with climate warming and the degradation of hydraulic structures caused by their long-term operation. Such destruction of waterworks occurs in China, Russia, and South America. Despite the severe consequences, many countries do not take serious measures to reduce the risk of catastrophic flooding. Last year, there was a threat of a dam break in the Akmola region in Kazakhstan. The lack of a spillway created a threat of a dam break [4]. Inconsistency in the actions of regional leaders led to the destruction of the dam and flooding of the regional center.
International experience in the design, construction and operation of hydraulic structures shows that the risk of flooding can be eliminated or significantly reduced with the help of an emergency prevention system. One of the prevention measures is the creation of an effective state system of dam safety.
Hydraulic structures are dangerous and unique objects that have their own specifics and complex operation, requiring systematic work to improve their technical condition and increase the degree of safety. However, to date, many countries have not formed a state system for ensuring the safety of hydraulic structures, which reduces not only the effectiveness of the measures used, but also does not allow developing strategic areas of interaction.
Another important factor that regulates the state of water facilities is the lack or weak legal framework. Regulations do not always take into account modern realities and specifics of hydraulic structures.
The problem of safety of hydraulic structures has a cross-border context. Therefore, States using shared watercourses are obliged to take measures to prevent accidents at hydraulic structures that will negatively affect the natural and social environment of neighboring States.
To improve the safety of hydraulic structures, it is also necessary to conduct comprehensive research on the development of new structures with increased throughput and high reliability parameters for long-term operation, as well as those that are maximally adapted to local conditions.
References
1. https://www.zakon.kz/5020378-proryv-damby-v-uzbekistane-v.html
2. https://www.facebook.com/100011304071409/posts/1109023966151062/?d=n