The New Zealand landslide dam database, v1.0

Abstract

Landslide dams, forming when a landslide blocks a watercourse, are significant components of slope-river systems. Dams can fail suddenly and catastrophically, threatening downstream populations and structures. So it is important to understand where they could form, how long they persist in the landscape, and the extent of downstream inundation once they fail. To investigate dam formation, longevity, and stability effectively in Aotearoa New Zealand, we present version 1.0 of the New Zealand Landslide Dam Database (NZLDD). The database includes compilation, mapping, and/or remapping of 1036 dams, including those generated by the 2016 Kaikōura Earthquake. A representative subset of 265 dams was selected to analyse dam stability and breaching in detail (ongoing work). The database architecture, description of datasets included, attribute definitions, and some summary statistics are presented here. Many dams in the database have formed in greywacke bedrock terrain, by earthquake-triggered rock avalanches, falls, and slides. Most are small (Dam Type I—small dam that does not reach opposite valley side), and have since failed and no longer impede or impound water. The NZLDD represents a significant increase in catalogued landslide dams—almost doubling the existing number of known and studied dams worldwide.

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