Current Members
Heidi NepfDonald and Martha Harleman Professor
Margaret MacVicar Fellow
Fellow, American Geophysical Union
ASCE, Hunter Rouse Hydraulic Engineering Award
Chi Epsilon Honor Member
Distinguished Engineering Alumni Award – Bucknell University
18th Harold Jan Schoemaker Award
NSF Career Award
School of Engineering Bose Award for Excellence in Teaching
Samual M. Seegal Prize, MIT – for inspiring student in pursuing excellence
Earll Murman Award for Excellence in Undergraduate Advising
Tian ZhaoGraduate Student
I am examining sediment transport. In my undergraduate studies, I had field experiences observing suspended cohesive sediment transport on tidal flats. In particular, my trips to coastal saltmarshes in Jiangsu, China, have set me thinking about how marsh plant species like Spartina alterniflora and Spartina anglica will interact with local sediment transport and morphodynamics, and how researchers can integrate vegetation-induced turbulence and drag into sediment transport models. To study these problems, I have started my graduate career in the Nepf Lab in Fall 2018.
Isabella SchalkoResearch Affiliate, Nepf Environmental Fluid Mechanics Laboratory, MIT
Senior Research Assistant, Laboratory of Hydraulics, Hydrology and Glaciology (VAW), ETH Zurich
Numerous rivers have been confined and are eco-morphologically impaired, resulting in an increased demand for river restoration projects. Wood placements are a common and inexpensive measure for river restoration. To plan and evaluate river restoration projects including wood accumulations, it is important to understand the interactions between flow, wood, and sediment. Using physical modeling, my project aims to quantify flow and morphological structures associated with different wood accumulation setups. The results will be used to develop design recommendations for wood accumulations.
Rachel SchaeferGraduate Student
I grew up on the East Coast and have spent many summers in the Great Lakes region. It’s easy to take for granted the roles that vegetation play in nature, and view plants as ugly weeds to clear instead of species to protect. Seagrasses provide important habitat, carbon sinks, and other ecological functions, but are threatened by overdevelopment, pollution, and climate change. Long meadows of seagrass have been shown to attenuate currents and attenuate wave energy, but the dynamics of wave damping in the presence of currents are not as well understood. In addition, the morphological characteristics of plants vary widely in scope and in their relative contributions to vegetation-induced drag in oscillatory flow. I plan to investigate these areas to improve our understanding of the complex but ubiquitous interactions between flow and vegetation. Improved models of flow interactions with vegetation can help predict how storms and currents will affect vulnerable meadows, and help design infrastructure and living shorelines to protect coastal areas.
Yuan XuVisiting Graduate Student from Tsinghua University
The evolution of vegetated landscape occurs through the interplay of flow, vegetation, and sediment transport. There is a lack of predictive models that accurately account for the impact of vegetation morphology on sediment transport. Most previous studies have only considered circular cylinders as a model for vegetation. My study focuses on the sediment transport in channels with realistic models of emergent cattail. First, flume experiments will be used to describe and predict the turbulence level and form drag within a canopy of cattails. Second, the incipient sediment motion will be investigated and compared with the bare channel. Finally, I will attempt to construct a theoretical model that predicts sediment transport rate in channels with different distributions of realistic cattail models.
Autumn DeitrickGraduate Student
Coastal environments, such as mangrove forests, provide an unparalleled amount of ecosystem services, from water purification and flood prevention to the mitigation of climate change. In the Nepf Lab, I will investigate the critical conditions for erosion and deposition within black mangrove’s pneumatophores, which are also known as pencil roots because of their vertical and pencil-like shape. Pencil roots have an influence on sediment transport. They can both generate turbulence that can promote erosion and slow the currents near the bed that can promote deposition. If we know these critical conditions, then we can better understand the sediment fate and transport as well as how much carbon is stored in mangrove forests.
To determine these critical conditions, I am combining field work conducted in Port Fourchon, LA with laboratory methods. I will then use my observational field data and laboratory results to construct sub-grid scale models for erosion and deposition, which will be incorporated into a coastal-scale model to explore the role of channels in optimizing sediment retention within mangrove forests.
Rovi PorterMEng Student
Historically, logjams have been removed from rivers due to concerns of flooding, erosion, and destruction of property. However, new research has demonstrated that logjams have beneficial properties including generating pools that protect salmoniod spawing, propagule retention sites, and increasing biodiversity. For these reasons, engineered logjams are being introduced into rivers across the Northwest of the United States. To better identify the key components that enable logjams to create suitable habitat for salmonid fish, I am conducting physical experiments with model logjams. These experiments vary the dimensions and solid volume fraction of the log jam, and measure the velocity and turbulence in the wake. After characterizing the dimensional effects of the logjams, suggestions on which type of logjam is most suitable given what is known about fish preference are made.
Simone LassarUndergraduate Student
When water with excess sediment flows through gravel streams it can clog the small spaces in between the gravel, known as interstitial spaces. These interstitial spaces are important for young fish, such as trout and salmon. I will work on a project modeling how sediment clogs up gravel streams, and investigate how adding obstacles (like logs, rocks, etc.) to these streams affects clogging. The turbulence created by adding these obstructions create can alleviate clogging, so this project aims to quantify if and how much clogging is prevented.
Chuyan ZhaoVisiting Graduate Student from Dalian University of Technology
zhaocy(at)mit.edu
My research focuses on sediment transport in a submerged flexible meadow influenced by waves and current. Previous studies have shown that the near bed turbulence is the main trigger for sediment resuspension. In my study, I will measure vertical profiles of velocity and sediment concentration under different hydrodynamics conditions and uses these measurement to predict the threshold level of turbulence for sediment resuspension and deposition. Moreover, I will also consider how submerged flexible vegetation influences the formation of ripples in wave and current flow.
For profiles of lab alumni, visit the alumni page.
