I am a research professor in the UMass Amherst Geoscience department. I am interested in how human perturbations to flows of water and sediment affect physical and ecological systems. This broad interest is divided into a few main study areas:
- How do coastal conditions drive the evolution of tidal wetland systems? What changes can we expect in a warming climate with increases in extreme weather and the rate of sea level rise.
- How do changes in catchment processes – both local land use and climate-related – affect the deliver of sediment from upland areas to lakes, reservoirs, and the coast.
- How do riparian aquifers adjacent to rivers respond to natural and anthropogenic changes in river discharge?
Here are some current projects that I am working on:
Dams and Sediment on the Hudson– along with collaborators at Woods Hole Oceanographic Inst. and the Hudson River National Estuarine Research Reserve, we are helping river managers and dam owners better understand the sediment impacts of dam removal on the Hudson River estuary. With input from an advisory committee made up of stakeholders with a variety of perspectives, this project produced a tool for dam owners to make an initial assessment of sediment inventory in their dam as they weigh dam removal. Three papers are forthcoming: (1) aggregate impacts of dams trapping sediments; (2) response of Hudson tidal marshes to channel modifications; (3) turbidity hysteresis following 2011 Hurricane Irene. Data from this project can be found at UMass Scholarworks data repository.
Preprints from this research:
Effects of potential dam removals on the Hudson’s sediment budget: https://doi.org/10.1002/essoar.10502519.1
Dynamic Tidal Wetlands – Current and projected rates of sea level rise threaten to drown tidal marshes along coastlines. Tidal marshes mitigate storm impacts to vulnerable coastal infrastructure and provide myriad ecosystem services. I am currently working on tidal wetlands in the Northeast US and the Caribbean Islands that have undergone dynamic growth or decline over the last 100 years. Selected study sites have all experienced a dramatic change in coastal morpholoogy or hydrology which likely catalyzed rapid marsh growth or decline. By studying the conditions that allowed for rapid marsh expansion or collapse, we can better prepare to seed new marshes and restore those that suffer as sea levels continue to rise.
Historical Perspectives on Sediment Mitigation– Along with Scott Steinschneider and Keith Ahn (both of Cornell), I am studying the sediment archives in one of New York City’s largest water supply reservoirs. NYC is one of five municipalities in the country that holds a filtration avoidance permit from the EPA, allowing them to distribute unfiltered (but treated) water to its customers. This permit was acquired and is maintained through NYC’s exceptional watershed management program, which ensures high quality source water. Sediment in the reservoir’s bottom informs us as to how well various measures over the last century have fared in reducing sediment loading of the reservoir. This is the first paper that has come out of this research.
Sustainability and Hydroelectricity– Hydroelectric power is often touted as a clean solution to energy challenges. However, hydroelectric generation comes with myriad well-documented adverse effects. Along with Eve Vogel and others at UMass, I am studying how changes to energy markets have affected the operation of hydroelectric facilities and in turn affected downstream river reaches.
Extreme Event Sedimentology – Destructive floods from rainfall and coastal storm surge can leave sedimentary layers in lagoons, reservoirs, and lakes that are distinct from background sedimentation. I use sediment cores to understand changes in past frequency and magnitude of these extreme events. By coupling modern observations with sedimentology, we can extend inferences from often short-term gauge records to longer time-spans. Ongoing research is examining the erosivity of Hurricane Maria in the uplands of Puerto Rico.
Hydropeaking and Riparian Forests– Hydropeaking – hydroelectic dam releases corresponding to periods of energy demand and price increases – has been shown to cause water to be lost from downstream river reaches. During a release, river water downstream of the dam is pushed into the bank, removing much of it from the river and denying it from downstream users such as farmers, municipalities, and ecosystems. I am studying how this water is taken up by trees and to what extent hydropeaking robs rivers of their water.
Teaching I have a masters of education in secondary science and taught for three years as a Teach for America corps member at a public school in rural Hawaii. As an instructor at UMass, I was awarded the university’s most prestigious teaching award (two awarded per year). Here are some courses that I have taught:
- Introductory Geology
byellen < a t > geo.umass.edu