10/1/19 AEG Dinner Meeting - Hydrogeology of the Atlantic Highlands

This meeting is available for sponsorship,
please see below for more details,
and contact our chapter Treasurer Niall Henshaw at niall.henshaw@parsons.com

 

ABSTRACT
For over a century, rainfall-induced shallow slope failures on the precipitous bluffs in the Atlantic Highlands, New Jersey have adversely affected residential properties, roads, buried utilities, a railroad, and a coastal trail, and in at least one incident threatened life safety. Most of the documented landslides involved failure of sandy slope colluvium, landslide deposits, or fill and were associated with either tropical cyclones in summer and early fall or nor’easters in late fall through early spring. Empirical data on documented landslide occurrences and rainfall characteristics suggest a higher critical rainfall threshold for slope failure during summer and early fall than during the remainder of the year. Hydrologic and slope movement monitoring data from two sites in the Atlantic Highlands have yielded insights into the seasonal variation in soil moisture conditions, hydrologic storm response, and the stability of slope colluvium and recent landslide deposits. Few storms during the period of monitoring have approached the preliminary critical rainfall thresholds except for a short-duration cloudburst on August 7, 2018, which resulted in multiple shallow slope failures. This presentation summarizes information on antecedent moisture conditions and the variation in the hydrologic storm response with both location and depth during that event.


BIOGRAPHY
Francis Ashland is currently a research geologist with the Landslide Hazards Program of the U.S. Geological Survey (USGS). His research focuses on anticipating future landslide occurrences and involves hydrologic and slope movement monitoring at a variety of landslides in Nashville, Pittsburgh, the Catskills, southwestern Utah, and the Atlantic Highlands. Previously, he was a senior geologist at the Utah Geological Survey where his research focused on landslide and earthquake ground shaking hazards. He also worked as a staff engineering geologist at a geotechnical engineering firm in Boston, specializing in rock slope stability and tunnels. His work in the Atlantic Highlands is in collaboration with Alex Fiore and Pam Reilly at the USGS New Jersey Water Science Center. He currently lives in an always-needing-repair, historic farmhouse in northern Virginia with his wife, daughter, goats, ducks, chickens, mule, and horse.