Which of the following is/are the potential threat to safety of large dams ? 1. Urbanisation near dam sites 2. Flash floods in catchment area 3. Seismic activities in surrounding area Select the correct answer using the code given below:

Large dams face multiple safety threats. Seismic activities pose a significant risk, as earthquakes can cause ground deformation, liquefaction, and structural damage to dam foundations and embankments [3]. Historical events, such as the Wenchuan earthquake, demonstrate that seismic shocks can damage thousands of dams and hydropower plants. Flash floods in the catchment area are another critical threat; extreme rainfall can lead to overtopping, which is the most common failure mode for embankment dams. While dams are built to control floods, excessive rainfall and sedimentation can trigger failures [2]. Urbanization near dam sites exacerbates these risks; urban reservoirs are particularly vulnerable to extreme rainfall, and dam failure in such areas causes catastrophic damage to life and property due to the high density of human establishments [3]. Therefore, urbanization, flash floods, and seismic activities are all recognized threats to dam safety.

Sources

1. [3] https://www.nature.com/articles/s41598-024-78968-1
2. [2] NCERT. (2022). Contemporary India II: Textbook in Geography for Class X (Revised ed.). NCERT. > Chapter 3: The Making of a Global World > p. 57