DAM FAILS MORAPEDI D. KEALEBOGA 18000268 JEFFESON SEREPUDI 180001042 A dam is a barrier across flowing water that obstructs, directs or slows down the flow, often creating a reservoir, lake or impoundments. Dam failure is a catastrophic type of failure characterized by the sudden, rapid, and uncontrolled release of impounded water or the likelihood of such an uncontrolled release with considerable loss of life or property Collapse of a dam in the Chi-Chi, Taiwan, 1999 earthquake Causes of Dam Failure Piping Internal erosion of the foundation or embankment caused by seepage is known as piping. Generally, erosion starts at the downstream toe and works back toward the reservoir, forming channels or pipes under the dam. 20% of U.S. dam failures have been caused by piping Overtopping Dam overtopping means water passing over the top of dam. This condition arises when the passage provided to pass the flood (Spillway) is unable to discharge the coming inflow Foundation defects These failures occur as a result of settling in the foundation of the dam, instability of slopes surrounding the dam, uplift pressures, and seepage around the foundation. All of these failures result in structural instability and potential dam failure Other causes of dam failures could be: Natural phenomenon; earthquake and landslides Human error, including poor maintenance or poor design Walnut Grove Dam Located 30 miles by river north of Wickenburg on the Hassayampa River Built in 1886-87 the dam was built to provide water for irrigation and gold placer mining The dam failed due to overtopping on February 22, 1890 the ensuing flood caused an estimated 150 deaths and extensive destruction of property. The failure was blamed on inadequate capacity of the spillway and poor construction (ADEM, March 1998) Walnut Grove Dam Dunlap Dam A reservoir on the Guadalupe river in Guadalupe county, Texas, US Formed in 1931 Gate collapsed in May 14, 2019 The collapse was due to ageing structural steel No fatalities recorded, no damaged infrastructure Video of Dunlop dam collapsing Effects of Dam Failure Loss of life Loss of property Economic setback Loss of resources Dam failure prevention Using more materials for construction to prevent easy wearing Increase in the size and length of the dam walls Regular maintenance checks Design the bank and excavation so that the upstream edge of the pit will be covered when the dam is full. This will help to prevent erosion of the edge of the pit. Consequence minimization Presentation: should always be prepared and planned ahead Assessment: one problem is identified assessment is necessary, to see exactly the magnitude and potential damage that could occur and which plan to follow Response: public safety should be number one Documentation: for future use References J.M.K.C. Donev et al. (2019). Energy Education - Dam failures, viewed July 2, 2020 https://energyeducation.ca/encyclopedia/Dam_failures. J Fail. Anal. and Preven. (2011). A Brief Assessment of a Dam and Its Failure Prevention, Journal of Failure Analysis and Prevention. 11(2),pp 97–109