Design considerations of glacial lake outburst floods and secondary hazards of earthquakes for hydropower projects

This paper describes the heavy damage to a hydropower project caused by the secondary hazards of a destructive earthquake and by a glacial lake outburst flood (GLOF) within two consecutive years. The original design was reviewed through the development of its rehabilitation concept, and the mechanisms of the damage effects of the events were studied. On this basis, several design considerations are outlined to improve the structural resistance to destructive effects, which can be translated into design criteria and specifications and are useful for the design and construction of a hydropower project situated in a high seismic region or exposed to a GLOF risk. A case study indicated that the effects of aftershocks on a hydropower structure might be greater than those of major earthquakes, depending on the distance from the epicenter to the structure. Therefore, the effects of near-field and far-field earthquakes should be considered in design work. Unlike the term PMF suggested, GLOF is frequently larger than probable maximum flood (PMF). The design considerations recommended in this paper provide useful information for compiling a design standard or guidelines. This paper also provides a reference for outburst floods of earthquake-formed barrier lakes or other landslide dams.