A Scientist's Life: Adam Young

Coastal morphologist assesses erosion risk with drone-based lasers, photogrammetry, and buried sensors

Adam Young is a coastal geomorphologist at Scripps institution of Oceanography at the University of California San Diego. He received his bachelor’s degree from Cal Poly University San Luis Obispo in 1999 and his PhD in engineering from UC San Diego in 2006. He joined Scripps Oceanography in 2007.

explorations now: What do you do for a living?

Adam Young: I study coastal processes and how the coastline changes over time. My particular expertise is in coastal erosion: understanding how fast the coast is eroding and why.

One of my specialties is using field observations to measure coastal cliff erosion and the forcing mechanisms to understand processes that drive the erosion. The primary drivers of coastal cliff erosion include wave activity, and subaerial processes such as rainfall and groundwater. These processes are difficult to separate because they often occur at the same time during storm events, and operate in various feedback mechanisms. Recently I have been focusing on quantifying the relationship between waves and resulting erosion. We know that wave erosion is a fundamental process but it has not yet been quantified very well, partly because field observations of the process are extremely limited. My recent field studies in San Diego collected some of the most detailed observations ever of these processes. These new field observations are being used to develop quantitative relationships needed to advance coastal retreat forecast models.

One of the primary objectives of my research is to better understand how the coastline is evolving now, so that we can make better predictions for the future. This is important because we know sea level is rising, but we don't know exactly how the coastline will respond. The response will vary by location and is likely to cause significant societal impacts. There is a lot of infrastructure along our coastline; not just homes but also railways, highways, wastewater treatment plants, military facilities, nuclear power plants, and more. Future conditions will also impact our beaches which are important for recreation, generate billions of tourism dollars annually in California, and provide a natural defense to backshore and cliff erosion.

en: What are some of the main questions in your field?

AY:   One question is what's going to happen in the future; in order to understand that, we need to understand what has happened in the past, and what is happening right now, and why. We need better and more detailed long term field studies to accurately answer these questions. This is where my research is based: building detailed long term data sets of coastal processes and change.

The coastline is a unique place where the ocean, the land, and the atmosphere all intersect. Each one of those elements is important in controlling how the coastline evolves over time, and each involves many different components such as waves and tides, sand, cliffs, cobble, and bedrock, rainfall and groundwater, seawalls, and other infrastructure. These many interacting components make coastal change very complex. Research often focuses on only one or two of these components, but my research aims to take a more comprehensive approach to better understand the processes and feedbacks between these different elements of the coastal system.

en: What are some of the tools of your trade?

AY: Recently I have been using a laser mapping system called lidar (light detection and ranging) that generates very high resolution 3-dimensional maps of the coast. We also use high resolution photographs and photogrammetry techniques to generate 3-d models. The lidar data are typically collected using a pickup truck driving along the beach, but we use drones as well. Each survey provides a snapshot in time that we can compare to other survey data to measure and track the erosion over time with very fine detail. The Scripps coastal mapping program started about 20 years ago. Surveys were initially conducted with ATV- and GPS-based surveys and focused on beaches and bathymetry, but the addition of lidar expanded the program’s capabilities. The lidar is a great new asset allowing us to simultaneously map new parts of the coast including the cliffs, cobble, and bedrock for a more comprehensive approach so we can investigate how those components actually interact together.  Currently we routinely map the coastline from the Mexican border to Coronado and La Jolla to Oceanside.

Some other key tools involve measurements of waves impacting the cliffs. I use sensors buried in the beach that measure the size and frequency of waves impacting the cliffs. I also use seismometers buried in the cliff top to measure cliff shaking from wave-cliff impacts. These tools and applications are constantly developing and improving, but have allowed us to develop some of the first relationships between waves and erosion. These are key measurements for improved predictions of future coastal retreat.

en: Why did you want to come to Scripps?

AY: The main motivation was that I wanted to continue my coastal erosion work that I had completed as a graduate student, learn more about coastal processes, and work with renowned experts. And, of course, Scripps has an amazing coastal field program and collects some of the best field observations in the world. The coastal field group has designed and developed numerous very specialized pieces of equipment that allow us to obtain some amazing datasets. It's really great to be at Scripps and have access to that information and infrastructure, and the ability to conduct these field studies.

en: Finally, for beachgoers out there, what are some signs of imminent cliff collapse to look out for?

AY: Places you may want to stay away from include anything that's very steep or over vertical. Cliffs that are undercut – where there are deep notches in the bottom of the cliffs –  are very unstable. If you see cracking in the cliff face or in the cliff top, that's a good sign of a future failure. Often, when a cliff collapses, it actually occurs in a series of events, not just one failure. A cliff failure can be active for a period of days, weeks, or even months, so if you see fresh debris at the bottom of a cliff, then it's a good idea to stay away from that area. Elevated rainfall and groundwater often trigger failures in our area, but it is important to remember that cliff failures can happen at anytime.

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