Preliminary estimation of catchment capacity to develop debris flows and their runout distances using high resolution Digital Elevation Models (DEMs)

Authors: Mark Bloomberg, David Palmer
Publication: New Zealand Journal of Forestry, Volume N.Z.J.For. 2020, Issue N.Z.J.For. 65(4) 2021, pp 26-31, Jan 2021
Publisher: New Zealand Institute of Forestry

Abstract: Given recent occurrences of debris flow landslides from harvested forests in New Zealand, it is important to investigate the likelihood of debris flows from these sites. In this study, we examine simple methods for 1) identifying catchments where debris flows can initiate, and for those catchments 2) estimating the length of the debris flow runout zone. To do this, we use Ligar Bay (located on the north coast of the South Island, New Zealand) as a study area. In December 2011, Ligar Bay was subjected to a severe rainfall event, which led to devastating debris flows and associated debris floods. The effects of these debris flows were documented by GNS Science and their report is compared with the results of our analysis.