New Zealand has over 3,000 earth embankment dams and canals, many of which were constructed prior to the evolution of modern granular filter criteria for dam design in the mid-1980s. Tekapo Canal is one such structure, constructed from 1971 to 1977 as a 26 km long conveyance canal, linking two hydropower stations in the inland Canterbury region. Tekapo canal is constructed of widely-graded soils of glacial origin. Challenges with material compaction and constructability were reported during construction.
Earth embankment dams form a vital part of New Zealand’s hydropower, agricultural, and water supply infrastructure. The challenges faced in the management of aging embankment dams are compounded by factors specific to New Zealand, including large variability in soil types and the highly tectonic environment in which the dams are located. Internal erosion, triggered by both seismic and non-seismic events, is considered one of the primary risks to New Zealand embankment dams. This study considers the applicability of existing empirical methods to assess the potential for internal erosion and highlights significant shortcomings in the applicability of existing screening methods used to assess the potential for internal erosion in New Zealand soils.