Discuss the risks associated with the flow of water below dams and Essay

Discuss the risks associated with the flow of water below dams and define the critical hydraulic gradient - Essay Example When the downward force on such soil particles equals the upward force, the soil particles are at zero stress. This allows a free movement of dam subsurface soil particles which serves to enhance already existing seepage. The afore mentioned seepage leads in turn to the creation of channels that catalyze dam sub surface flows in a process known better as piping (Rogers, 2010). A number of different environmental failures have occurred on account of flows below dams that eventually lead to compromised embankments and a sudden discharge of water after dam failure. The sudden release of water from such dam failures tends to devastate the ecosystems downstream of the failed dam. A relevant concept in such failures is the critical hydraulic gradient () that allows a calculation of when piping failures are most likely. In itself, the critical hydraulic gradient depends on the composition of the dam sub surface soil, the available head at the dam’s bottom wall and the void ratio of the soil mass. The critical hydraulic gradient is seen as the hydraulic gradient that occurs when the vertical stress becomes zero (Vijayendra, 2012). Mathematically, the critical hydraulic gradient can be expressed as shown below (Vijayendra, 2012): As mentioned earlier, any loopholes in the calculation for the critical hydraulic gradient can mean the difference between dam failure and safe dam operation. There have been instances where dams have failed with only little warning due to the development of piping failures in the dam’s sub surface soil. It is worth mentioning here that such dam failures are often rapid and provide little warning before hand of impending doom. One such case in point is the Baldwin Hills Reservoir failure where the embankment failed only after 9 years of service. There were essentially no major warnings before the failure