Ted Langhorst

Hi, I'm Ted Langhorst.

About

About Me

I'm a postdoctoral researcher at the University of Massachusetts at Amherst using deep learning to better estimate sediment flux in rivers. I grew up in Columbus, Ohio, just a few miles from Ohio State's campus where I got my B.S. in Geophysics. I started research as an undergraduate by building a hydrodynamic model of the Olentangy River, a small, urban stream that flows through the city. A few years later, I started a Masters and PhD at the University of North Carolina at Chapel Hill working on large rivers all over the world using field methods and decades of satellite images to measure long-term river bank migration and suspended sediment fluxes.

Projects

Sagavanirktok River

Sediment transport on the Sagavanirktok River, Alaska

Remote sensing of river discharge and suspended sediment concentration has seen big improvements in the past decade. It's now possible to combine these algorithms to use satellite images to estimate the sediment flux of a river. This work is currently in preparation, but has been years in the making, with the first remote sensing work being completed in 2019 and field work in 2021 and 2022 for validation data. This project was the impetus for OpenOBS, after realizing I did not have the budget for even 1 deployable commercial turbidity sensor. We have used these sensors extensively in the Sag, deploying 10 each year in order to monitor months of turbidity changes in high resolution.

Ellie Friedmann installing sensors in the Sag.

The sensor setup for one site (2 OpenOBS and a pressure logger) before being installed in 2022.

The Sag at low flow in August 2021, showing off its gravel bed and headwaters in the Brooks Range Mountains.

Pulling rebar-mounted sensors at the end of the 2021 season.

IGEA

Integrating Geosciences and Engineering in the Arctic (IGEA)

IGEA is a unique class taught in three parts by Colin Gleason at UMass Amherst. In the Fall, undergraduate students learn how to plan and prepare for field science studying Arctic Hydrology. The students then follow through with their plans at Toolik Field Station on the North Slope of Alaska that Summer with the help of graduate students. Finally, the students analyze their data and write a report in the Spring. The science objectives were broadly defined in the NSF CAREER grant to Gleason which gives the students lots of freedom to follow their interests.

Likely explaining something tangential that I found interesting.

Group 2 from the 2021 IGEA class on a snowy day.

Group 1 from 2022 navigating to their sites, walking 2km over frozen tundra.

Global Riverbank Erosion

Riverbank Erosion and Accretion from Landsat (REAL)

Riverbank erosion presents a real threat to people who live near the banks of active rivers, yet understanding and predicting it at large scales is extremely difficult. One impediment to these predictions is a globally representative dataset of riverbank changes over long time scales. This project is attempting to fill that gap by processing global maps of surface water extent to extract river extents over the past two decades to calculate rates of erosion and accretion.

Publication in JGR:ES

Global map of riverbank erosion with insets showing the Amazon Basin and Purus River.

Methods for calculating riverbank erosion and accretion from maps of surface water.

Visualization of annual river maps of the Madre de Dios River in Bolivia.

SWOT Cal/Val

SWOT Calibration and Validation (Cal/Val) methods development

SWOT is expected to launch in 2022, but in the decade preceding the launch there has been a lot of work done to establish the best ways to make on-the-ground measurements underneath SWOT. Namely, quantifying water surface elevations down to centimeter scale and surface water extent to a few meters. I have been participated in and lead several field campaigns starting with the Summer of 2017 in Canada and Alaska. This work will kick in to full scale in 2023 with the launch of SWOT and carried out by full-time researchers at UNC, UMass Amherst, CU Boulder, and the Jet Propulsion Laboratory.

Precision GNSS base station running on the bank of a river in Canada to survey the water surface elevation.

Precision GNSS rover, depth sounder, and ADCP set up on a boat for river surveying.

OpenOBS development

Open-source Optical Backscatter Sensor (OpenOBS): DIY Turbidity sensors

Optical backscatter sensors are instruments commonly used to determine the turbidity (cloudiness) of water, or how much particulate matter is in the water. OpenOBS is an academic research project to develop an open source, affordable, easy to build, and accurate OBS. While commercial sensors cost upwards of $2000, OpenOBS can be built for less than $50 in parts. This low-cost alternative allows us to more extensively monitor natural systems, or use in high-risk environments, where deployment of a large number of commercial sensors would be cost-prohibitive.

Documentation site
Publication in Nature Water

An assemebled OBS with housing cut open for visualization.

Graphical interface for programming the sensor before deploying.

Full schematic of the data logger.

Theodore (Ted)
Langhorst