Implications of slope aspect for landslide risk assessment: A case study of Hurricane Maria in Puerto Rico in 2017

Abstract

Slope aspect is one of the topographic indices related to the rain-induced landslides. However, its role and importance are still debatable. We argue that due to the predictable patterns of hurricane wind circulations in various regional settings, the potential predominant landslide locations can be forecasted in advance of the approaching hurricanes by considering, in addition to other factors, the wind circulation patterns and the slope aspects. Recently (2019) published data from the United States Geological Survey (USGS) on the landslide distribution in Puerto Rico in relation to the impact of hurricane Maria (2017) provided a new opportunity to evaluate the role of the slope aspect on the occurrence of landslides.The results show association of the predominant number of landslides with the northern (NW, N, and NE) slope aspects followed by the SW and W aspects. This pattern is attributed to the wind circulation patterns and associated wind-driven rainfall during hurricane Maria impact on Puerto Rico. Vegetation damage (based on non-photosynthetic vegetation spectral response) was closely associated with landslides and the prevailing slope aspect in N and SW directions. Obtained results contribute to debates on the role of slope aspect in landslide risk assessment by providing an evidence of association between slope aspect and rain-induced landslide occurrences.