Capturing the transient hydrological response in sandy soils during a rare cloudburst associated with shallow slope failures—a case study in the Atlantic Highlands, New Jersey, USA.

A cloudburst on August 7, 2018, in the coastal bluffs of the Atlantic Highlands, New Jersey induced flooding, erosion, and multiple shallow slope failures that adversely impacted the surrounding hillside residential area. Historically, short-duration deluges are rare in the New York Bay region, with only eight cloudbursts of greater magnitude documented since 1948. The coastal bluffs consist of a variably thick, sandy surficial material overlying flat lying, mostly non-indurated Cretaceous and Tertiary sediments, including some low permeability glauconitic units. The bluffs have been impacted by both historical deep-seated and shallow landslide movement, the latter typically related to heavy, relatively long-duration rainfall associated with tropical cyclones and nor'easters. The shallow hydrological response during the rare cloudburst was captured at two hydrological monitoring sites and yielded insights into rapidly changing moisture conditions resulting in slope failure. Additional information is provided on historical cloudbursts that have affected the region, antecedent moisture conditions, and documented landslide types and processes.Supplementary material: A USGS ScienceBase data release of the time-series monitoring data accompanies the publication of this paper https://doi.org/10.5066/P9A601HC.